2016 by the American College of Cardiology Foundation, the American Heart Association, Inc., and the Heart Rhythm Society. Circulation is available at http://circ.ahajournals.org DOI: 10.1161/CIR.0000000000000311 2015 ACC/AHA/HRS Guideline for the Management of Adult Patients With Supraventricular Tachycardia A Report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines and the Heart Rhythm Society WRITING COMMITTEE MEMBERS* Richard L. Page, MD, FACC, FAHA, FHRS, Chair; Jos A. Joglar, MD, FACC, FAHA, FHRS, Vice Chair; Mary A. Caldwell, RN, MBA, PhD, FAHA; Hugh Calkins, MD, FACC, FAHA, FHRS* ; Jamie B. Conti, MD, FACC* ; Barbara J. Deal, MD ; N.A. Mark Estes III, MD, FACC, FAHA, FHRS* ; Michael E. Field, MD, FACC, FHRS ; Zachary D. Goldberger, MD, MS, FACC, FAHA, FHRS ; Stephen C. Hammill, MD, FACC, FHRS ; Julia H. Indik, MD, PhD, FACC, FAHA, FHRS ; Bruce D. Lindsay, MD, FACC, FHRS* ; Brian Olshansky, MD, FACC, FAHA, FHRS* ; Andrea M. Russo, MD, FACC, FHRS* ; Win-Kuang Shen, MD, FACC, FAHA, FHRS ; Cynthia M. Tracy, MD, FACC ; Sana M. Al-Khatib, MD, MHS, FACC, FAHA, FHRS, Evidence Review Committee Chair ACC/AHA TASK FORCE MEMBERS Jonathan L. Halperin, MD, FACC, FAHA, Chair; Glenn N. Levine, MD, FACC, FAHA, Chair-Elect; Jeffrey L. Anderson, MD, FACC, FAHA, Immediate Past Chair ; Nancy M. Albert, PhD, RN, FAHA ; Sana M. Al-Khatib, MD, MHS, FACC, FAHA; Kim K. Birtcher, PharmD, AACC; Biykem Bozkurt, MD, PhD, FACC, FAHA; Ralph G. Brindis, MD, MPH, MACC; Joaquin E. Cigarroa, MD, FACC; Lesley H. Curtis, PhD, FAHA; Lee A. Fleisher, MD, FACC, FAHA; Federico Gentile, MD, FACC; Samuel Gidding, MD, FAHA; Mark A. Hlatky, MD, FACC; John Ikonomidis, MD, PhD, FAHA; Jose Joglar, MD, FACC, FAHA; Richard J. Kovacs, MD, FACC, FAHA ; E. Magnus Ohman, MD, FACC ; Susan J. Pressler, PhD, RN, FAHA; Frank W. Sellke, MD, FACC, FAHA ; Win-Kuang Shen, MD, FACC, FAHA ; Duminda N. Wijeysundera, MD, PhD *Writing committee members are required to recuse themselves from voting on sections to which their specific relationships with industry and other entities may apply; see Appendix 1 for recusal information. HRS Representative. ACC/AHA Representative. ACC/AHA Task Force on Performance Measures Liaison. ACC/AHA Task Force on Clinical Practice Guidelines Liaison. Former Task Force member; current member during this writing effort. This document was approved by the American College of Cardiology Board of Trustees and Executive Committee, the American Heart Association Science Advisory and Coordinating Committee, and the Heart Rhythm Society Board of Trustees in August 2015 and the American Heart Association Executive Committee in September 2015. The Author Comprehensive Relationships Data Supplement is available with this article at http://circ.ahajournals.org/lookup/suppl/doi:10.1161/ CIR.0000000000000311/-/DC1. The Data Supplement files are available with this article at http://circ.ahajournals.org/lookup/suppl/doi:10.1161/CIR.0000000000000311/-/DC2. The American Heart Association requests that this document be cited as follows: Page RL, Joglar JA, Caldwell MA, Calkins H, Conti JB, Deal BJ, Estes NAM 3rd, Field ME, Goldberger ZD, Hammill SC, Indik JH, Lindsay BD, Olshansky B, Russo AM, Shen W-K, Tracy CM, Al-Khatib SM. 2015 ACC/AHA/ HRS guideline for the management of adult patients with supraventricular tachycardia: a report of theAmerican College of Cardiology/American HeartAssociation Task Force on Clinical Practice Guidelines and the Heart Rhythm Society. Circulation. 2016;133;e506-e574. doi: 10.1161/CIR.0000000000000311. This article has been copublished in the Journal of the American College of Cardiology and HeartRhythm Journal. Copies: This document is available on the World Wide Web sites of the American College of Cardiology (www.acc.org), the American Heart Association (professional.heart.org), and the Heart Rhythm Society (www.hrsonline.org). A copy of the document is available at http://professional.heart. org/statements by using either Search for Guidelines & Statements or the Browse By Topic area. To purchase additional reprints, call 843-216-2533 or e-mail kelle.ramsay@wolterskluwer.com. Expert peer review of AHA Scientific Statements is conducted by the AHA Office of Science Operations. For more on AHA statements and guidelines development, visit http://professional.heart.org/statements. Select the Guidelines & Statements drop-down menu, then click Publication Development. Permissions: Multiple copies, modification, alteration, enhancement, and/or distribution of this document are not permitted without the express permission of the American Heart Association. Instructions for obtaining permission are located at http://www.heart.org/HEARTORG/General/Copyright- Permission-Guidelines_UCM_300404_Article.jsp. A link to the Copyright Permissions Request Form appears on the right side of the page. ACC/AHA/HRS Guideline Page et al 2015 ACC/AHA/HRS SVT Guideline e507 Table of Contents Preamble e507 1. Introduction e508 1.1. Methodology and Evidence Review e508 1.2. Organization of the GWC e510 1.3. Document Review and Approval e510 1.4. Scope of the Guideline e510 2. General Principles e510 2.1. Mechanisms and Definitions e510 2.2. Epidemiology, Demographics, and Public Health Impact e510 Evaluation of the Patient With Suspected or Documented SVT e511 Clinical Presentation and Differential Diagnosis on the Basis of Symptoms e511 2.3.2. Evaluation of the ECG e514 2.4. Principles of Medical Therapy e515 2.4.1. Acute Treatment: Recommendations e515 Ongoing Management: Recommendations e517 Basic Principles of Electrophysiological Study, Mapping, and Ablation e518 Mapping With Multiple and Roving Electrodes e518 Tools to Facilitate Ablation, Including 3-Dimensional Electroanatomic Mapping e518 Mapping and Ablation With No or Minimal Radiation e519 2.5.4. Ablation Energy Sources e519 3. Sinus Tachyarrhythmias e520 3.1. Physiological Sinus Tachycardia e521 3.2. Inappropriate Sinus Tachycardia e521 3.2.1. Acute Treatment e521 3.2.2. Ongoing Management: Recommendations e521 4. Nonsinus Focal Atrial Tachycardia and MAT e523 4.1. Focal Atrial Tachycardia e523 4.1.1. Acute Treatment: Recommendations e526 4.1.2. Ongoing Management: Recommendations e527 4.2. Multifocal Atrial Tachycardia e527 4.2.1. Acute Treatment: Recommendation e531 4.2.2. Ongoing Management: Recommendations e531 5. Atrioventricular Nodal Reentrant Tachycardia e531 5.1. Acute Treatment: Recommendations e532 5.2. Ongoing Management: Recommendations e533 6. Manifest and Concealed Accessory Pathways e534 Management of Patients With Symptomatic Manifest or Concealed Accessory Pathways e535 6.1.1. Acute Treatment: Recommendations e535 6.1.2. Ongoing Management: Recommendations e536 6.2. Management of Asymptomatic Pre-Excitation . e537 6.2.1. PICOTS Critical Questions e537 Asymptomatic Patients With Pre-Excitation: Recommendations e538 Risk Stratification of Symptomatic Patients With Manifest Accessory Pathways: Recommendations e539 7. Atrial Flutter e539 7.1. Cavotricuspid Isthmus Dependent Atrial Flutter . e539 7.2. Non Isthmus-Dependent Atrial Flutters e540 7.3. Acute Treatment: Recommendations e541 7.4. Ongoing Management: Recommendations e542 8. Junctional Tachycardia e544 8.1. Acute Treatment: Recommendations e544 8.2. Ongoing Management: Recommendations e545 9. Special Populations e545 9.1. Pediatrics e545 9.2. Patients With Adult Congenital Heart Disease e549 9.2.1. Clinical Features e549 9.2.2. Acute Treatment: Recommendations e550 9.2.3. OngoingManagement:Recommendations e551 9.3. Pregnancy e553 9.3.1. Acute Treatment: Recommendations e553 9.3.2. Ongoing Management: Recommendations e554 9.4. SVT in Older Populations e555 Acute Treatment and Ongoing Management: Recommendation e555 10. Quality-of-Life Considerations e555 11. Cost-Effectiveness e555 12. Shared Decision Making e556 13. Evidence Gaps and Future Research Needs e556 References e557 Appendix 1. Author Relationships With Industry and Other Entities (Relevant) e570 Appendix 2. Reviewer Relationships With Industry and Other Entities (Relevant) e571 Appendix 3. Abbreviations e574 Preamble Since 1980, the American College of Cardiology (ACC) and American Heart Association (AHA) have translated scientific evidence into clinical practice guidelines with recommendations to improve cardiovascular health. These guidelines, based on systematic methods to evaluate and classify evidence, provide a cornerstone of quality cardio- vascular care. In response to reports from the Institute of Medicine1,2 and a mandate to evaluate new knowledge and maintain relevance at the point of care, the ACC/AHA Task Force on Clinical Practice Guidelines (Task Force) modified its methodology.3 5 The relationships between guidelines, data standards, appro- priate use criteria, and performance measures are addressed Intended Use Practice guidelines provide recommendations applicable to patients with or at risk of developing cardiovascular dis- ease. The focus is on medical practice in the United States, but guidelines developed in collaboration with other organi- zations may have a broader target. Although guidelines may inform regulatory or payer decisions, they are intended to improve quality of care in the interest of patients. Evidence Review Guideline Writing Committee (GWC) members review the lit- erature; weigh the quality of evidence for or against particular tests, treatments, or procedures; and estimate expected health outcomes. In developing recommendations, the GWC uses evidence-based methodologies that are based on all available Literature searches focus on randomized controlled trials (RCTs) but also include registries, nonrandomized comparative and descriptive studies, case series, cohort stud- ies, systematic reviews, and expert opinion. Only selected ref- erences are cited. The Task Force recognizes the need for objective, indepen- dent Evidence Review Committees (ERCs) that include meth- odologists, epidemiologists, clinicians, and biostatisticians who systematically survey, abstract, and assess the evidence to address key clinical questions posed in the PICOTS format (P=population, I=intervention, C=comparator, O=outcome, Practical considerations, including time and resource constraints, limit the ERCs to evidence that is relevant to key clinical questions and lends itself to sys- tematic review and analysis that could affect the strength of corresponding recommendations. Recommendations devel- oped by the GWC on the basis of the systematic review are marked SR . Guideline-Directed Medical Therapy The term guideline-directed medical therapy refers to care defined mainly by ACC/AHA Class I recommendations. For these and all recommended drug treatment regimens, the reader should confirm dosage with product insert mate- rial and carefully evaluate for contraindications and interac- tions. Recommendations are limited to treatments, drugs, and devices approved for clinical use in the United States. Class of Recommendation and Level of Evidence The Class of Recommendation (COR; ie, the strength of the rec- ommendation) encompasses the anticipated magnitude and cer- taintyofbenefitinproportiontorisk.TheLevelofEvidence(LOE) rates evidence supporting the effect of the intervention on the basis of the type, quality, quantity, and consistency of data from clinical trials and other reports (Table 1).5,7 Unless otherwise stated, recom- mendations are sequenced by COR and then by LOE.Where com- parative data exist, preferred strategies take precedence. When >1 drug, strategy, or therapy exists within the same COR and LOE and no comparative data are available, options are listed alphabetically. Each recommendation is followed by supplemental text linked to supporting references and evidence tables. Relationships With Industry and Other Entities The ACC and AHA sponsor the guidelines without com- mercial support, and members volunteer their time. The Task Force zealously avoids actual, potential, or perceived con- flicts of interest that might arise through relationships with industry or other entities (RWI). All GWC members and reviewers are required to disclose current industry relation- ships or personal interests from 12 months before initiation of the writing effort. Management of RWI involves selecting a balanced GWC and assuring that the chair and a majority of committee members have no relevant RWI (Appendix 1). Members are restricted with regard to writing or voting on sec- tions to which their RWI apply. For transparency, members comprehensive disclosure information is available online. Comprehensive disclosure information for the Task Force is also available online. The Task Force strives to avoid bias by selecting experts from a broad array of backgrounds represent- ing different geographic regions, sexes, ethnicities, intellectual perspectives/biases, and scopes of clinical practice, and by inviting organizations and professional societies with related interests and expertise to participate as partners or collaborators. Individualizing Care in Patients With Associated Conditions and Comorbidities Managing patients with multiple conditions can be complex, especially when recommendations applicable to coexisting ill- nesses are discordant or interacting.8 The guidelines are intended to define practices meeting the needs of patients in most, but not all, circumstances. The recommendations should not replace clinical judgment. Clinical Implementation Management in accordance with guideline recommendations is effective only when followed. Adherence to recommendations can be enhanced by shared decision making between clinicians and patients, with patient engagement in selecting interventions based on individual values, preferences, and associated con- ditions and comorbidities. Consequently, circumstances may arise in which deviations from these guidelines are appropriate. Policy The recommendations in this guideline represent the official policy of the ACC and AHA until superseded by published addenda, statements of clarification, focused updates, or revised full-text guidelines. To ensure that guidelines remain current, new data are reviewed biannually to determine whether recommendations should be modified. In general, full revisions are posted in 5-year cycles.3,5 Jonathan L. Halperin, MD, FACC, FAHA Chair, ACC/AHA Task Force on Clinical Practice Guidelines 1.1. Methodology and Evidence Review The recommendations listed in this guideline are, whenever possible, evidence based. An extensive evidence review was conducted in April 2014 that included literature published through September 2014. Other selected references published through May 2015 were incorporated by the GWC. Literature included was derived from research involving human subjects, published in English, and indexed in MEDLINE (through PubMed), EMBASE, the Cochrane Library, the Agency for Healthcare Research and Quality, and other selected databases relevant to this guideline. The relevant data are included in evidence tables in the Online Data Supplement. Key search words included but were not limited to the following: abla- tion therapy (catheter and radiofrequency; fast and slow pathway), accessory pathway (manifest and concealed), antiarrhythmic drugs, atrial fibrillation, atrial tachycardia, atrioventricular nodal reentrant (reentry, reciprocating) tachycardia, atrioventricular reentrant (reentry, reciprocat- ing) tachycardia, beta blockers, calcium channel blockers, cardiac imaging, cardioversion, cost effectiveness, cryother- apy, echocardiography, elderly (aged and older), focal atrial tachycardia, Holter monitor, inappropriate sinus tachycardia, Page et al 2015 ACC/AHA/HRS SVT Guideline e509 junctional tachycardia, multifocal atrial tachycardia, parox- ysmal supraventricular tachycardia, permanent form of junc- tional reciprocating tachycardia, pre-excitation, pregnancy, quality of life, sinoatrial node, sinus node reentry, sinus tachycardia, supraventricular tachycardia, supraventricular arrhythmia, tachycardia, tachyarrhythmia, vagal maneuvers (Valsalva maneuver), and Wolff-Parkinson-White syndrome. Additionally, the GWC reviewed documents related to supra- ventricular tachycardia (SVT) previously published by the ACC, AHA, and Heart Rhythm Society (HRS). References selected and published in this document are representative and not all-inclusive. An independent ERC was commissioned to perform a systematic review of key clinical questions, the results of which were considered by the GWC for incorporation into this guideline. The systematic review report on the management of asymptomatic patients with Wolff-Parkinson-White (WPW) syndrome is published in conjunction with this guideline.9 Table 1. Applying Class of Recommendation and Level of Evidence to Clinical Strategies, Interventions, Treatments, or Diagnostic Testing in Patient Care* 1.2. Organization of the GWC The GWC consisted of clinicians, cardiologists, electrophysi- ologists (including those specialized in pediatrics), and a nurse (in the role of patient representative) and included representa- tives from the ACC, AHA, and HRS. 1.3. Document Review and Approval This document was reviewed by 8 official reviewers nomi- nated by the ACC, AHA, and HRS, and 25 individual content reviewers. Reviewers RWI information was distributed to the GWC and is published in this document (Appendix 2). This document was approved for publication by the gov- erning bodies of the ACC, the AHA, and the HRS. 1.4. Scope of the Guideline The purpose of this joint ACC/AHA/HRS document is to provide a contemporary guideline for the management of adults with all types of SVT other than atrial fibrillation (AF). Although AF is, strictly speaking, an SVT, the term SVT generally does not refer to AF. AF is addressed in the 2014 ACC/AHA/HRS Guideline for the Management of Atrial Fibrillation (2014 AF guideline).10 The present guide- line addresses other SVTs, including regular narrow QRS complex tachycardias, as well as other, irregular SVTs (eg, atrial flutter with irregular ventricular response and multi- focal atrial tachycardia [MAT]). This guideline supersedes the 2003 ACC/AHA/ESC Guidelines for the Management of Patients With Supraventricular Arrhythmias. 11 It incor- porates new and existing knowledge derived from published clinical trials, basic science, and comprehensive review arti- cles, along with evolving treatment strategies and new drugs. Some recommendations from the earlier guideline have been updated as warranted by new evidence or a better under- standing of existing evidence, whereas other inaccurate, irrelevant, or overlapping recommendations were deleted or modified. Whenever possible, we reference data from the acute clinical care environment; however, in some cases, the reference studies from the invasive electrophysiology labo- ratory inform our understanding of arrhythmia diagnosis and management. Although this document is aimed at the adult population ( 18 years of age) and offers no specific recom- mendations for pediatric patients, as per the reference list, we examined literature that included pediatric patients. In some cases, the data from noninfant pediatric patients helped inform this guideline. In the current healthcare environment, cost consider- ation cannot be isolated from shared decision making and patient-centered care. The AHA and ACC have acknowl- edged the importance of value in health care, calling for eventual development of a Level of Value for practice rec- ommendations in the 2014 ACC/AHA Statement on Cost/ Value Methodology in Clinical Practice Guidelines and Although quality-of-life and cost- effectiveness data were not sufficient to allow for devel- opment of specific recommendations, the GWC agreed the data warranted brief discussion (Sections 10 and 11). Throughout this document, and associated with all rec- ommendations and algorithms, the importance of shared decision making should be acknowledged. Each approach, ranging from observation to drug treatment to ablation, must be considered in the setting of a clear discussion with the patient regarding risk, benefit and personal preference. See Section 12 for additional information. In developing this guideline, the GWC reviewed prior pub- lished guidelines and related statements. Table 2 contains a list of guidelines and statements deemed pertinent to this writing effort and is intended for use as a resource, thus obviating the need to repeat existing guideline recommendations. 2. General Principles 2.1. Mechanisms and Definitions For the purposes of this guideline, SVT is defined as per Table 3, which provides definitions and the mechanism(s) of each type of SVT. The term SVT does not generally include AF, and this document does not discuss the manage- ment of AF. 2.2. Epidemiology, Demographics, and Public Health Impact The epidemiology of SVT, including its frequency, pat- terns, causes, and effects, is imprecisely defined because of incomplete data and failure to discriminate among AF, atrial flutter, and other supraventricular arrhythmias. The best available evidence indicates that the prevalence of SVT in the general population is 2.29 per 1000 persons.32 When adjusted by age and sex in the US population, the incidence of paroxysmal supraventricular tachycardia (PSVT) is esti- mated to be 36 per 100 000 persons per year.32 There are approximately 89 000 new cases per year and 570 000 per- sons with PSVT.32 Compared with patients with cardiovas- cular disease, those with PSVT without any cardiovascular disease are younger (37 versus 69 years; P=0.0002) and have faster PSVT (186 bpm versus 155 bpm; P=0.0006). Women have twice the risk of men of developing PSVT.32 Individuals >65 years of age have >5 times the risk of younger persons of developing PSVT.32 Patients with PSVT who are referred to specialized cen- ters for management with ablation are younger, have an equal sex distribution, and have a low frequency of cardio- The frequency of atrioventricular nodal reentrant tachycardia (AVNRT) is greater in women than in men. This may be due to an actual higher incidence in women, or it may reflect referral bias. In persons who are middle-aged or older, AVNRT is more common, whereas in adolescents, the prevalence may be more balanced between atrioventricular reentrant tachycardia (AVRT) and AVNRT, or AVRT may be more prevalent.32 The relative frequency of tachycardia mediated by an accessory pathway decreases with age. The incidence of manifest pre-excitation or WPW pattern on ECG tracings in the general population is 0.1% to 0.3%. However, not all patients with manifest ventricu- lar pre-excitation develop PSVT.47 49 The limited data on the public health impact of SVT indicate that the arrhythmia is commonly a reason for emergency department and primary care physician visits but is infrequently the primary reason for hospital admission.11,50,51 Page et al 2015 ACC/AHA/HRS SVT Guideline e511 2.3. Evaluation of the Patient With Suspected or Documented SVT 2.3.1. Clinical Presentation and Differential Diagnosis on the Basis of Symptoms Patients seen in consultation for palpitations often describe symptoms with characteristic features suggestive of SVT that may guide physicians to appropriate testing and a definitive diagnosis. The diagnosis of SVT is often made in the emergency department, but it is common to elicit symptoms suggestive of SVT before initial electrocardiogram/electrocardiographic (ECG) documentation. SVT symptom onset often begins in adulthood; in 1 study in adults, the mean age of symptom onset was 32 18 years of age for AVNRT, versus 23 14 years of age In contrast, in a study conducted in pediatric popu- lations, the mean ages of symptom onset of AVRT and AVNRT In comparison with AVRT, patients with AVNRT are more likely to be female, with an age AVNRT onset has been reported after the age of 50 years in 16% and before the age of 20 years in Among women with SVT and no other cardiovascular disease, the onset of symptoms occurred during childbearing years (eg, 15 to 50 years) in 58%.32 The first onset of SVT occurred in only 3.9% of women during pregnancy, but among women with an established history of SVT, 22% reported that pregnancy exacerbated their symptoms.58 SVT has an impact on quality of life, which varies according to the frequency of episodes, the duration of SVT, and whether symptoms occur not only with exercise but also at rest.53,59 retrospective study in which the records of patients <21 years of age with WPW pattern on the ECG were reviewed, 64% of patients had symptoms at presentation, and an additional 20% developed symptoms during follow-up.60 Modes of presentation included documented SVT in 38%, palpitations in 22%, chest pain in 5%, syncope in 4%, AF in 0.4%, and sudden cardiac death (SCD) in 0.2%.60 Although this was a pediatric population, it provided symptom data that are likely applicable to adults. A confounding factor in diagnosing SVT is the need to differen- tiate symptoms of SVT from symptoms of panic and anxiety disorders or any condition of heightened awareness of sinus tachycardia (such as postural orthostatic tachycardia syndrome). In 1 study, the criteria for panic disorder were fulfilled in 67% of patients with SVT that remained unrecognized after their ini- tial evaluation. Physicians attributed symptoms of SVT to panic, anxiety, or stress in 54% of patients, with women more likely to be mislabeled with panic disorder than men.61 When AVNRT and AVRT are compared, symptoms appear to differ substantially. Patients with AVNRT more frequently describe symptoms of shirt flapping or neck pounding 54,62 that may be related to pulsatile reversed flow when the right atrium contracts against a closed tricuspid valve (cannon a-waves). During 1 invasive study of patients with AVNRT and AVRT, both arrhythmias decreased arterial pressure and increased left atrial pressure, but simulation of SVT mecha- nism by timing the pacing of the atria and ventricles showed significantly higher left atrial pressure in simulated AVNRT than in simulatedAVRT.62 Polyuria is particularly common with AVNRT and is related to higher right atrial pressures and ele- vated levels of atrial natriuretic protein in patients with AVNRT compared with patients who have AVRT or atrial flutter.63 Table 2. Associated Guidelines and Statements Title Organization Publication Year (Reference) Guidelines Atrial fibrillation AHA/ACC/HRS 201410 Stable ischemic heart disease ACC/AHA/ACP/ AATS/ PCNA/ SCAI/STS Valvular heart disease AHA/ACC 201414 Assessment of cardiovascular risk Heart failure ACC/AHA 201316 Antithrombotic therapy for valvular heart disease Atrial fibrillation ESC 201218 Device-based therapy ACC/AHA/HRS 201220 Atrial fibrillation CCS 201421 Hypertrophic cardiomyopathy ACC/AHA 201123 Secondary prevention and risk reduction therapy for patients with coronary and other atherosclerotic vascular disease Adult congenital heart disease * Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC VII) Statements Catheter ablation in children and patients with congenital heart disease Postural tachycardia syndrome, inappropriate sinus tachycardia, and vasovagal syncope Arrhythmias in adult congenital heart disease Catheter and surgical ablation of atrial fibrillation CPR and emergency cardiovascular care * *A revision to the current document is being prepared, with publication expected in late 2015. AATS indicates American Association for Thoracic Surgery; ACC, American College of Cardiology; ACCP, American College of Chest Physicians; ACP, American College of Physicians; AHA, American Heart Association; CCS, Canadian Cardiovascular Society; CPR, cardiopulmonary resuscitation; ECAS, European Cardiac Arrhythmia Society; EHRA, European Heart Rhythm Association; ESC, European Society of Cardiology; HRS, Heart Rhythm Society; JNC, Joint National Committee; NHLBI, National Heart, Lung, and Blood Institute; PACES, Pediatric and Congenital Electrophysiology Society; PCNA, Preventive Cardiovascular Nurses Association; SCAI, Society for Cardiovascular Angiography and Interventions; and STS, Society of Thoracic Surgeons. Table 3. Relevant Terms and Definitions Arrhythmia/Term Definition Supraventricular tachycardia (SVT) An umbrella term used to describe tachycardias (atrial and/or ventricular rates in excess of 100 bpm at rest), the mechanism of which involves tissue from the His bundle or above. These SVTs include inappropriate sinus tachycardia, AT (including focal and multifocal AT), macroreentrant AT (including typical atrial flutter), junctional tachycardia, AVNRT, and various forms of accessory pathway-mediated reentrant tachycardias. In this guideline, the term does not include AF. Paroxysmal supraventricular tachycardia (PSVT) A clinical syndrome characterized by the presence of a regular and rapid tachycardia of abrupt onset and termination. These features are characteristic of AVNRT or AVRT, and, less frequently, AT. PSVT represents a subset of SVT. Atrial fibrillation (AF) A supraventricular arrhythmia with uncoordinated atrial activation and, consequently, ineffective atrial contraction. ECG characteristics include: 1) irregular atrial activity, 2) absence of distinct P waves, and 3) irregular R-R intervals (when atrioventricular conduction is present). AF is not addressed in this document. Sinus tachycardia Rhythm arising from the sinus node in which the rate of impulses exceeds 100 bpm. Physiologic sinus tachycardia Appropriate increased sinus rate in response to exercise and other situations that increase sympathetic tone. Inappropriate sinus tachycardia Sinus heart rate >100 bpm at rest, with a mean 24-h heart rate >90 bpm not due to appropriate physiological responses or primary causes such as hyperthyroidism or anemia. Atrial tachycardia (AT) Focal AT An SVT arising from a localized atrial site, characterized by regular, organized atrial activity with discrete P waves and typically an isoelectric segment between P waves. At times, irregularity is seen, especially at onset ( warm-up ) and termination ( warm-down ). Atrial mapping reveals a focal point of origin. Sinus node reentry tachycardia A specific type of focal AT that is due to microreentry arising from the sinus node complex, characterized by abrupt onset and termination, resulting in a P-wave morphology that is indistinguishable from sinus rhythm. Multifocal atrial tachycardia (MAT) An irregular SVT characterized by 3 distinct P-wave morphologies and/or patterns of atrial activation at different rates. The rhythm is always irregular. Atrial flutter Cavotricuspid isthmus dependent atrial flutter: typical Macroreentrant AT propagating around the tricuspid annulus, proceeding superiorly along the atrial septum, inferiorly along the right atrial wall, and through the cavotricuspid isthmus between the tricuspid valve annulus and the Eustachian valve and ridge. This activation sequence produces predominantly negative sawtooth flutter waves on the ECG in leads 2, 3, and aVF and a late positive deflection in V1. The atrial rate can be slower than the typical 300 bpm (cycle length 200 ms) in the presence of antiarrhythmic drugs or scarring. It is also known as typical atrial flutter or cavotricuspid isthmus dependent atrial flutter or counterclockwise atrial flutter. Cavotricuspid isthmus dependent atrial flutter: reverse typical Macroreentrant AT that propagates around in the direction reverse that of typical atrial flutter. Flutter waves typically appear positive in the inferior leads and negative in V1. This type of atrial flutter is also referred to as reverse typical atrial flutter or clockwise typical atrial flutter. Atypical or non cavotricuspid isthmus dependent atrial flutter Macroreentrant ATs that do not involve the cavotricuspid isthmus. A variety of reentrant circuits may include reentry around the mitral valve annulus or scar tissue within the left or right atrium. A variety of terms have been applied to these arrhythmias according to the re-entry circuit location, including particular forms, such as LA flutter and LA macroreentrant tachycardia or incisional atrial re-entrant tachycardia due to re-entry around surgical scars. Junctional tachycardia A nonreentrant SVT that arises from the AV junction (including the His bundle). Atrioventricular nodal reentrant tachycardia (AVNRT) A reentrant tachycardia involving 2 functionally distinct pathways, generally referred to as fast and slow pathways. Most commonly, the fast pathway is located near the apex of Koch s triangle, and the slow pathway inferoposterior to the compact AV node tissue. Variant pathways have been described, allowing for slow-slow AVNRT. Typical AVNRT AVNRT in which a slow pathway serves as the anterograde limb of the circuit and the fast pathway serves as the retrograde limb (also called slow-fast AVNRT ). Atypical AVNRT AVNRT in which the fast pathway serves as the anterograde limb of the circuit and a slow pathway serves as the retrograde limb (also called fast-slow AV node reentry ) or a slow pathway serves as the anterograde limb and a second slow pathway serves as the retrograde limb (also called slow-slow AVNRT ). Accessory pathway For the purpose of this guideline, an accessory pathway is defined as an extranodal AV pathway that connects the myocardium of the atrium to the ventricle across the AV groove. Accessory pathways can be classified by their location, type of conduction (decremental or nondecremental), and whether they are capable of conducting anterogradely, retrogradely, or in both directions. Of note, accessory pathways of other types (such as atriofascicular, nodo-fascicular, nodo-ventricular, and fasciculoventricular pathways) are uncommon and are discussed only briefly in this document (Section 7). Manifest accessory pathways A pathway that conducts anterogradely to cause ventricular pre-excitation pattern on the ECG. (Continued) Page et al 2015 ACC/AHA/HRS SVT Guideline e513 True syncope is infrequent with SVT, but complaints of light-headedness are common. In patients with WPW syn- drome, syncope should be taken seriously but is not neces- sarily associated with increased risk of SCD.64 The rate of AVRT is faster when AVRT is induced during exercise,65 yet the rate alone does not explain symptoms of near- syncope. Elderly patients with AVNRT are more prone to syncope or near-syncope than are younger patients, but the tachycardia rate is generally slower in the elderly.66,67 The drop in blood pressure (BP) during SVT is greatest in the first 10 to 30 seconds and somewhat normalizes within 30 to 60 seconds, despite minimal changes in rate.68,69 Shorter ventriculoatrial intervals are associated with a greater mean decrease in BP.69 Studies have demonstrated a relationship between hemodynamic changes and the relative timing of atrial and ventricular activation. In a study of patients with AVNRT with short versus long ventriculoatrial intervals, there was no significant difference in tachycardia cycle ; however, the induction of typical AVNRT caused a marked initial fall in systemic BP, followed by only partial recovery that resulted in stable hypotension and a reduction in cardiac output due to a decrease in stroke volume. In comparison, atypical AVNRT, having a longer ventriculoatrial interval, exhibited a lesser degree of initial hypotension, a complete recovery of BP, and no significant change in cardiac output.70 The contrasting hemodynamic responses without sig- nificant differences in heart rate during SVT confirm that rate alone does not account for these hemodynamic changes. Atrial contraction on a closed valve might impair pulmonary drain- age and lead to neural factors that account for these observa- tions. These findings were confirmed in a study performed in the electrophysiological (EP) laboratory: When pacing was used to replicate the timing of ventricular and atrial activation during SVT, the decrease in BP was greatest with simultane- ous ventriculoatrial timing, smaller with a short vertriculoatrial interval, and smallest with a long ventriculoatrial interval.71 An increase in central venous pressure followed the same trend. Sympathetic nerve activity increased with all 3 pacing modali- ties but was most pronounced with simultaneous atrial and ventricular pacing or a short ventriculoatrial interval. In a study of the relationship of SVT with driving, 57% of patients with SVT experienced an episode while driving, and 24% of these considered it to be an obstacle to driving.72 This sentiment was most common in patients who had experienced syncope or near-syncope. Among patients who experienced SVT while driving, 77% felt fatigue, 50% had symptoms of near-syncope, and 14% experienced syncope. Women had more symptoms in each category. See Online Data Supplement 1 for additional data on clinical presentation and differential diagnosis on the basis of symptoms. Concealed accessory pathway A pathway that conducts only retrogradely and does not affect the ECG pattern during sinus rhythm. Pre-excitation pattern An ECG pattern reflecting the presence of a manifest accessory pathway connecting the atrium to the ventricle. Pre-excited ventricular activation over the accessory pathway competes with the anterograde conduction over the AV node and spreads from the accessory pathway insertion point in the ventricular myocardium. Depending on the relative contribution from ventricular activation by the normal AV nodal/His Purkinje system versus the manifest accessory pathway, a variable degree of pre-excitation, with its characteristic pattern of a short P-R interval with slurring of the initial upstroke of the QRS complex (delta wave), is observed. Pre-excitation can be intermittent or not easily appreciated for some pathways capable of anterograde conduction; this is usually associated with a low-risk pathway, but exceptions occur. Asymptomatic pre-excitation (isolated pre-excitation) The abnormal pre-excitation ECG pattern in the absence of documented SVT or symptoms consistent with SVT. Wolff-Parkinson-White syndrome Syndrome characterized by documented SVT or symptoms consistent with SVT in a patient with ventricular pre-excitation during sinus rhythm. Atrioventricular reentrant tachycardia (AVRT) A reentrant tachycardia, the electrical pathway of which requires an accessory pathway, the atrium, atrioventricular node (or second accessory pathway), and ventricle. Orthodromic AVRT An AVRT in which the reentrant impulse uses the accessory pathway in the retrograde direction from the ventricle to the atrium, and the AV node in the anterograde direction. The QRS complex is generally narrow or may be wide because of pre-existing bundle-branch block or aberrant conduction. Antidromic AVRT An AVRT in which the reentrant impulse uses the accessory pathway in the anterograde direction from the atrium to the ventricle, and the AV node for the retrograde direction. Occasionally, instead of the AV node, another accessory pathway can be used in the retrograde direction, which is referred to as pre-excited AVRT. The QRS complex is wide (maximally pre-excited). Permanent form of junctional reciprocating tachycardia (PJRT) A rare form of nearly incessant orthodromic AVRT involving a slowly conducting, concealed, usually posteroseptal accessory pathway. Pre-excited AF AF with ventricular pre-excitation caused by conduction over 1 accessory pathway(s). AF indicates atrial fibrillation; AT, atrial tachycardia; AV, atrioventricular; AVNRT, atrioventricular nodal reentrant tachycardia; AVRT, atrioventricular reentrant tachycardia; bpm, beats per minute; ECG, electrocardiogram/electrocardiographic; LA, left atrial; MAT, multifocal atrial tachycardia; PJRT, permanent form of junctional reciprocating tachycardia; PSVT, paroxysmal supraventricular tachycardia; SVT, supraventricular tachycardia; and WPW, Wolff-Parkinson-White. Table 3. Continued Arrhythmia/Term Definition 2.3.2. Evaluation of the ECG Figures 1 to 6 provide representative ECGs, with Figure 1 showing ventricular tachycardia (VT) and Figures 2 to 5 showing some of the most common types of these SVTs. A 12-lead ECG obtained during tachycardia and during sinus rhythm may reveal the etiology of tachycardia. For the patient who describes prior, but not current, symptoms of palpitations, the resting ECG can identify pre-excitation that should prompt a referral to a cardiac electrophysiologist. A wide-complex tachycardia (QRS duration >120 ms) may represent either VT or a supraventricular rhythm with abnormal conduction. Conduction abnormalities may be due to rate-related aberrant conduction, pre-existing bundle- branch block seen in sinus rhythm, or an accessory pathway that results in pre-excitation (Table 4). The presence of atrio- ventricular (AV) dissociation (with ventricular rate faster than atrial rate) or fusion complexes representing dissociation of supraventricular impulses from a ventricular rhythm provides the diagnosis of VT (Figure 1). Other criteria are useful but not diagnostic. Concordance of the precordial QRS com- plexes such that all are positive or negative suggests VT or pre-excitation, whereas QRS complexes in tachycardia that are identical to those seen in sinus rhythm are consistent with SVT. Other, more complicated ECG algorithms have been developed to distinguish VT from SVT, such as the Brugada criteria, which rely on an examination of the QRS morphol- ogy in the precordial leads,73 and the Vereckei algorithm, which is based on an examination of the QRS complex in lead (Table 5). The failure to correctly identify VT can be potentially life threatening, particularly if misdiagnosis results in VT being treated with verapamil or diltiazem. Adenosine is suggested in the 2010 AHA Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Part 8: Adult Advanced Cardiovascular Life Support (2010 Adult if a wide-complex tachycardia is mono- morphic, regular, and hemodynamically tolerated, because adenosine may help convert the rhythm to sinus and may help in the diagnosis. When doubt exists, it is safest to assume any wide-complex tachycardia is VT, particularly in patients with known cardiovascular disease, such as prior myocardial infarction. For a patient presenting in SVT, the 12-lead ECG can potentially identify the arrhythmia mechanism (Figure 7). The tachycardia should first be classified according to whether there is a regular or irregular ventricular rate.An irregular ven- tricular rate suggests AF, MAT, or atrial flutter with variable AV conduction. When AF is associated with a rapid ventricu- lar response, the irregularity of the ventricular response is less easily detected and can be misdiagnosed as a regular SVT.76 If the atrial rate exceeds the ventricular rate, then atrial flutter or AT (focal or multifocal) is usually present (rare cases of AVNRT with 2:1 conduction have been described77 ). If the SVT is regular, this may represent AT with 1:1 con- duction or an SVT that involves theAV node. Junctional tachy- cardias, which originate in the AV junction (including the His bundle), can be regular or irregular, with variable conduction to the atria. SVTs that involve the AV node as a required com- ponent of the tachycardia reentrant circuit include AVNRT and 6). In these reentrant tachycardias, the retrogradely con- ducted P wave may be difficult to discern, especially if bundle- branch block is present. In typical AVNRT, atrial activation is nearly simultaneous with the QRS, so the terminal portion of the P wave is usually located at the end of the QRS complex, appearing as a narrow and negative deflection in the inferior leads (a pseudo S wave) and a slightly positive deflection at the end of the QRS complex in lead V1 (pseudo R ). In ortho- dromic AVRT (with anterograde conduction down the AV node), the P wave can usually be seen in the early part of the ST-T segment. In typical forms of AVNRT and AVRT, because the P wave is located closer to the prior QRS complex than the subsequent QRS complex, the tachycardias are referred to as having a short RP. They also have a 1:1 relationship between the P wave and QRS complex, except in rare cases of AVNRT in which 2:1 AV block or various degrees of AV block can occur. In unusual cases of AVNRT (such as fast-slow ), the P wave is closer to the subsequent QRS complex, providing a long RP. The RP is also long during an uncommon form of AVRT, referred to as the permanent form of junctional recip- rocating tachycardia (PJRT), in which an unusual accessory bypass tract with decremental (slowly conducting) retro- grade conduction during orthodromicAVRT produces delayed atrial activation and a long RP interval. A long RP interval is typical of AT because the rhythm is driven by the atrium and conducts normally to the ventricles. In AT, the ECG will typically show a P wave with a morphol- ogy that differs from sinus that is usually seen near the end of or shortly after the T wave (Figure 5). In sinus node reentry Figure 1. ECG showing AV dissociation during VT in a patient with a wide QRS complex tachycardia. *P waves are marked with arrows. AV indicates atrioventricular; ECG, electrocardio- gram; and VT, ventricular tachycardia. Reproduced with permis- sion from Blomstr m-Lundqvist et al.11 Page et al 2015 ACC/AHA/HRS SVT Guideline e515 tachycardia, a form of focal AT, the P-wave morphology is identical to the P wave in sinus rhythm. 2.4. Principles of Medical Therapy See Figure 8 for the algorithm for acute treatment of tachy- cardia of unknown mechanism; Figure 9 for the algorithm for ongoing management of tachycardia of unknown mechanism; Table 6 for acute drug therapy for SVT (intravenous adminis- tration); and Table 7 for ongoing drug therapy for SVT (oral administration). 2.4.1. Acute Treatment: Recommendations Because patients with SVT account for approximately emer- gency physicians may be the first to evaluate patients whose tachycardia mechanism is unknown and to have the opportunity to diagnose the mechanism of arrhythmia. It is important to record a 12-lead ECG to differentiate tachy- cardia mechanisms according to whether the AV node is an obligate component (Section 2.3.2), because treatment that targets the AV node will not reliably terminate tachycardias Figure 2. Typical AVNRT and normal sinus rhythm after conversion. Upper panel: The arrow points to the P waves, which are inscribed at the end of the QRS complex, seen best in the inferior leads and as a slightly positive R (pseudo r prime) in lead V1. The reentrant circuit involves anterograde conduction over a slow atrioventricular node pathway, followed by retrograde conduction in a fast atrioventricular node pathway. Typical AVNRT is a type of short RP tachycardia. Middle panel: When the patient is in sinus rhythm, the arrow indicates where the R is absent in V1. Bottom panels: Magnified portions of lead V1 in AVNRT (left) and sinus rhythm (right) are shown. AVNRT indicates atrioventricular nodal reentrant tachycardia. that are not AV node dependent. Also, if the QRS duration is >120 ms, it is crucial to distinguish VT from SVT with aberrant conduction, pre-existing bundle-branch block, or pre-excitation (Table 4). In particular, the administration of verapamil or diltiazem for treatment of either VT or a pre-excited AF may lead to hemodynamic compromise or may accelerate the ventricular rate and lead to ventricular fibrillation. Recommendations for Acute Treatment of SVT of Unknown Mechanism COR LOE Recommendations I B-R 1. Vagal maneuvers are recommended for acute treatment in patients with regular SVT.82 84 See Online Data and 3. For acute conversion of SVT, vagal maneuvers, including Valsalva and carotid sinus massage, can be performed quickly and should be the first-line intervention to terminate SVT. These maneuvers should be performed with the patient in the supine position. Vagal maneuvers typically will not be effective if the rhythm does not involve the AV node as a requisite component of a reentrant circuit. There is no gold standard for proper Valsalva maneuver technique but, in general, the patient raises intrathoracic pressure by bearing down against a closed glottis for 10 to 30 seconds, equivalent to at least 30 mm Hg to 40 mm Hg.82,84 Carotid massage is performed after absence of bruit has been confirmed by auscultation, by applying steady pressure over the right or left carotid sinus Another vagal maneuver based on the classic diving reflex consists of applying an ice-cold, wet towel to the ; in a laboratory setting, facial immersion in water at 10 C (50 F) has proved effective in terminating tachycardia, as well.86 One study involving 148 patients with SVT demonstrated that Valsalva was more successful than carotid sinus massage, and switching from 1 technique to the other resulted in an overall success rate of 27.7%.82 The practice of applying pressure to the eyeball is potentially dangerous and has been abandoned. I B-R 2. Adenosine is recommended for acute treatment in patients with regular SVT.42,51,83,87 92 See Online Data and 3. Adenosine has been shown in nonrandomized trials in the emergency department or prehospital setting to effectively terminate SVT that is due to either AVNRT or AVRT, with success rates ranging from 78% to 96%. Although patients may experience side effects, such as chest discomfort, shortness of breath, and flushing, serious adverse effects are rare because of the drug s very short half-life.93 Adenosine may also be useful diagnostically, to unmask atrial flutter or AT, but it is uncommon for adenosine to terminate these atrial arrhythmias.91 It should be administered via proximal IV as a rapid bolus infusion followed by a saline flush. Continuous ECG recording during adenosine administration may help diagnostically and can also distinguish drug failure due to failure to terminate the arrhythmias versus successful termination with immediate arrhythmia reinitiation. I B-NR Synchronized cardioversion is recommended for acute treatment in patients with hemodynamically unstable SVT when vagal maneuvers or adenosine are ineffective or not feasible.94 See Online Data Supplement 3. Sinus rhythm must be promptly restored in patients with SVT who are hemodynamically unstable. The safety and effectiveness of cardioversion in the prehospital setting was analyzed in a cohort of patients with hemodynamically unstable SVT who had failed to convert with vagal maneuvers and intravenous pharmacological therapy, and cardioversion successfully restored sinus rhythm in all patients.94 The 2010 adult ACLS guideline75 advises synchronized cardioversion for any persistent SVT resulting in hypotension, acutely altered mental status, signs of shock, chest pain, or acute heart failure symptoms but recommends that adenosine be considered first if the tachycardia is regular and has a narrow QRS complex. Figure 3. Atypical AVNRT. Arrows point to the P wave. The reentrant circuit involves anterograde conduction over a fast atrioventricular node pathway, followed by retrograde conduction in a slow atrioventricular node pathway, resulting in a retrograde P wave (negative polarity in inferior leads) with long RP interval. This ECG does not exclude PJRT or a low septal atrial tachycardia, which can appear very similar to this ECG. AVNRT indicates atrioventricular nodal reentrant tachycardia; ECG, electrocardiogram; and PJRT, permanent form of junctional reciprocating tachycardia. Page et al 2015 ACC/AHA/HRS SVT Guideline e517 2.4.2. Ongoing Management: Recommendations The recommendations and algorithm (Figure 9) for ongoing management, along with other recommendations and algo- rithms for specific SVTs that follow, are meant to include consideration of patient preferences and clinical judgment; this may include consideration of consultation with a car- diologist or clinical cardiac electrophyisiologist, as well as patient comfort with possible invasive diagnostic and therapeutic intervention. Recommendations for treatment options (including drug therapy, ablation, or observation) must be considered in the context of frequency and dura- tion of the SVT, along with clinical manifestations, such as symptoms or adverse consequences (eg, development of cardiomyopathy). Recommendations for Ongoing Management of SVT of Unknown Mechanism COR LOE Recommendations I B-R Oral beta blockers, diltiazem, or verapamil is useful for ongoing management in patients with symptomatic SVT who do not have ventricular pre-excitation during sinus rhythm.46,98,99 See Online Data Supplement 2. Although many patients prefer to undergo potentially curative therapy with ablation, given its high success rate, and although ablation may be mandatory therapy for patients in certain occupations (eg, pilots, bus drivers), patients may prefer not to undergo ablation or may not have access to a cardiac electrophysiologist. In these latter cases, pharmacological therapy with AV nodal blockers is an appropriate option for long-term prophylactic therapy. Pharmacological therapy with verapamil (dosage up to 480 mg/day) has been studied in RCTs, with reductions documented in SVT episode frequency and duration as recorded by Holter monitoring or subjective episode frequency recording in diaries.98 Evidence for beta blockers is limited. One small study randomized patients with SVT to digoxin (0.375 mg/day), propranolol (240 mg/day), or verapamil (480 mg/day), with 1 week of placebo washout between drug regimens.99 Reduction in the number of episodes and duration of SVT (ascertained by diary and weekly 24-h Holter) was similar among the treatment groups, and all 3 medications were well tolerated.99 I B-NR 2. EP study with the option of ablation is useful for the diagnosis and potential treatment of SVT.36,100 106 See Online Data Supplement 2. EP testing with the option of ablation is useful as first-line therapy for treatment of symptomatic SVT, as it provides the potential for definitive cure without the need for chronic pharmacological therapy. Large registry studies report high success rates for ablation of both AVNRT and AVRT, with low frequency of potentially serious complications (Table 8). I C-LD 3. Patients with SVT should be educated on how to perform vagal maneuvers for ongoing management of SVT.82 See Online Data Supplement 2. When properly performed, vagal maneuvers can terminate SVT, so patient education on this maneuver may help to avoid a more prolonged tachycardia episode and reduce the need to seek medical attention. Vagal maneuvers should be performed with the patient in the supine position. Patients can be taught to perform a Valsalva maneuver by forcefully exhaling against a closed airway for 10 to 30 seconds, equivalent to at least 30 Another vagal maneuver based on the classic diving reflex consists of applying an ice-cold, wet towel to the face.85 IIa B-R Flecainide or propafenone is reasonable for ongoing management in patients without structural heart disease or ischemic heart disease who have symptomatic SVT and are not candidates for, or prefer not to undergo, catheter ablation.45,46,107 112 See Online Data Supplement 2. Several RCTs have demonstrated the efficacy of daily therapy with propafenone (450 mg/day to 900 mg/day) or flecainide (100 mg/day to 300 mg/day) to prevent recurrences of SVT in symptomatic patients.45,46,107 112 In 1 RCT, the probability of 12 months of effective (defined as <2 attacks of arrhythmia) and safe treatment was 86% for propafenone and 93% for flecainide.109 However, flecainide and propafenone have a risk of proarrhythmia in patients with structural heart disease or ischemic heart disease, so these drugs are contraindicated in these patient groups.113 These drugs, though often effective, have potential side effects and as such should be reserved for patients for whom beta blockers, diltiazem, or verapamil are ineffective or cannot be prescribed. I B-NR Synchronized cardioversion is recommended for acute treatment in patients with hemodynamically stable SVT when pharmacological therapy is ineffective or contraindicated.87,95 See Online Data and 10. Synchronized cardioversion is highly effective in terminating SVT (including AVRT and AVNRT), and when the patient is stable, this is performed after adequate sedation or anesthesia.94 Most stable patients with SVT respond to pharmacological therapy, with conversion success rates of 80% to 98% for agents such as verapamil, diltiazem, or adenosine. In some resistant cases, a second drug bolus or higher dose of initial drug agent might prove effective.87,96 Nevertheless, in rare instances, drugs may fail to successfully restore sinus rhythm, and cardioversion will be necessary. Synchronized cardioversion is inappropriate if the SVT is terminating and reinitiating spontaneously. IIa B-R 1. Intravenous diltiazem or verapamil can be effective for acute treatment in patients with hemodynamically stable SVT.87,89,92,97 See Online Data and 3. Intravenous diltiazem and verapamil have been shown to terminate SVT in 64% to 98% of patients. These drugs should be used only in hemodynamically stable patients. A slow infusion of either drug up to 20 minutes may lessen the potential for hypotension.97 It is important to ensure that tachycardia is not due to VT or pre-excited AF because patients with these rhythms who are given diltiazem or verapamil may become hemodynamically unstable or may have accelerated ventricular rate, which may lead to ventricular fibrillation. These agents are especially useful in patients who cannot tolerate beta blockers or experience recurrence after conversion with adenosine. Diltiazem and verapamil are not appropriate for patients with suspected systolic heart failure. IIa C-LD 2. Intravenous beta blockers are reasonable for acute treatment in patients with hemodynamically stable SVT.96 See Online Data Supplement 2. Evidence for the effectiveness of beta blockers in terminating SVT is limited. In a trial that compared esmolol with diltiazem, diltiazem was more effective in terminating SVT.96 Nonetheless, beta blockers have an excellent safety profile, so it is reasonable to use intravenous beta blockers to attempt to terminate SVT in hemodynamically stable patients. Recommendations for Acute Treatment of SVT of Unknown Mechanism (Continued) COR LOE Recommendations 2.5. Basic Principles of Electrophysiological Study, Mapping, and Ablation 2.5.1. Mapping With Multiple and Roving Electrodes An invasive EP study permits the precise diagnosis of the underlying arrhythmia mechanism and localization of the site of origin and provides definitive treatment if coupled with catheter ablation. There are standards that define the equip- ment and training of personnel for optimal performance of EP studies involve placement of multielectrode catheters in the heart at 1 sites in the atria, ventricles, or coronary sinus. Pacing and programmed electrical stimulation may be performed with or without pharmacological provoca- tion. Making a precise and correct diagnosis of the mechanism of SVT is the key to successful outcome, particularly when multiple arrhythmia mechanisms are possible; as such, appro- priate diagnostic maneuvers should be performed before pro- ceeding with ablation. By using diagnostic maneuvers during the EP study, the mechanism of SVT can be defined in most Complications of diagnostic EP studies are rare but can be life threatening.143 Cardiac mapping is performed during EP studies to iden- tify the site of origin of an arrhythmia or areas of critical conduction to allow targeting of ablation. Multiple techniques have been developed to characterize the temporal and spatial distribution of electrical activation.144 The simplest technique uses several multipole catheters plus a roving catheter that is sequentially positioned in different regions of interest and measures local activation time. Electroanatomic mapping sys- tems and specialized multielectrode catheters, such as circular or multispline catheters, can map simultaneously from mul- tiple sites and improve the speed and resolution of mapping. 2.5.2. Tools to Facilitate Ablation, Including 3-Dimensional Electroanatomic Mapping Several tools have been developed to facilitate arrhythmia mapping and ablation, including electroanatomic 3-dimen- sional mapping and magnetic navigation. Potential benefits of these technologies include more precise definition or localiza- tion of arrhythmia mechanism, spatial display of catheters and arrhythmia activation, reduction in fluoroscopy exposure for the patient and staff, and shortened procedure times, particu- larly for complex arrhythmias or anatomy.145 Disadvantages include higher cost, as well as additional training, support, and procedure preparation time. Several studies have dem- onstrated the advantages of electroanatomic mapping, with IIb B-R Sotalol may be reasonable for ongoing management in patients with symptomatic SVT who are not candidates for, or prefer not to undergo, catheter ablation.114 See Online Data Supplement 2. Sotalol is a class III antiarrhythmic agent with beta-blocker properties. Unlike flecainide and propafenone, it can be used in patients with structural heart disease or ischemic heart disease. One study randomized patients with reentrant SVT (AVNRT or AVRT) or other atrial tachyarrhythmias (eg, AF, atrial flutter, AT) to sotalol at a dose of 80 mg or 160 mg twice daily or placebo and found significant reductions in recurrence risk, including for patients with reentrant SVT, with no proarrhythmic adverse effects.114 Because of the potential for proarrhythmia, sotalol should be reserved for patients who are not candidates for catheter ablation and for whom beta blockers, diltiazem, or verapamil are ineffective or cannot be prescribed. IIb B-R Dofetilide may be reasonable for ongoing management in patients with symptomatic SVT who are not candidates for, or prefer not to undergo, catheter ablation and in whom beta blockers, diltiazem, flecainide, propafenone, or verapamil are ineffective or See Online Data Supplement 2. Dofetilide is a class III antiarrhythmic agent that, unlike sotalol, does not have beta-blocker properties. It may be reasonable in patients with structural heart disease or ischemic heart disease. In a trial of 122 patients randomized to dofetilide, propafenone, or placebo, the probability of remaining free of SVT after 6 months of treatment was 50% for dofetilide, 54% for propafenone, and 6% for placebo, with P<0.001 for either dofetilide or propafenone compared with placebo.107 Because of the potential for proarrhythmia, dofetilide should be reserved for patients who are not candidates for catheter ablation and for whom beta blockers, diltiazem, flecainide, verapamil, or propafenone are ineffective or cannot be prescribed. IIb C-LD Oral amiodarone may be considered for ongoing management in patients with symptomatic SVT who are not candidates for, or prefer not to undergo, catheter ablation and in whom beta blockers, diltiazem, dofetilide, flecainide, propafenone, sotalol, or verapamil are ineffective or contraindicated.115 See Online Data Supplement 2. Evidence for amiodarone for the ongoing management of SVT is limited. The drug was evaluated in a small retrospective study and was found to be effective in suppressing AVNRT during outpatient follow-up.115 Amiodarone is a second-line agent for patients who are not able to take beta blockers, diltiazem, dofetilide, flecainide, propafenone, sotalol, or verapamil given the toxicity and side effects that may develop with long-term amiodarone therapy. IIb C-LD Oral digoxin may be reasonable for ongoing management in patients with symptomatic SVT without pre-excitation who are not candidates for, or prefer not to undergo, catheter ablation.99 See Online Data Supplement 2. Evidence for the use of digoxin is limited. One small study randomized patients with SVT to digoxin (0.375 mg/day), propranolol (240 mg/day), and verapamil (480 mg/day), with 1 week of placebo washout between drug regimens.99 Overall, episodes and duration of SVT (ascertained by diary and weekly 24-h Holter) were similar, and all 3 medications were well tolerated.99 However, the dose of digoxin used was higher than that commonly used in clinical practice today, and in view of the risk of toxicity, digoxin should be reserved for patients who cannot take beta blockers, diltiazem, or verapamil or a class Ic agent (flecainide or propafenone) and must be used with caution in the presence of renal dysfunction. In some clinical studies, digoxin levels >1.2 ng/mL were associated with worse clinical outcomes, while levels <0.8 ng/mL were considered optimal; therefore, caution is advised.116 Recommendations for Ongoing Management of SVT of Unknown Mechanism (Continued) COR LOE Recommendations Page et al 2015 ACC/AHA/HRS SVT Guideline e519 success rates comparable to conventional approaches yet with significant reduction in fluoroscopy times.145 148 2.5.3. Mapping and Ablation With No or Minimal Radiation Fluoroscopy has historically been the primary imaging modal- ity used for EP studies. The use of ionizing radiation puts patient, operator, and laboratory staff at risk of the short- and long-term effects of radiation exposure. Attention to optimal fluoroscopic technique and adoption of radiation-reducing strategies can minimize radiation dose to the patient and oper- ator. The current standard is to use the as low as reasonably achievable (ALARA) principle on the assumption that there is no threshold below which ionizing radiation is free from harmful biological effect. Alternative imaging systems, such as electroanatomic mapping and intracardiac echocardiogra- phy, have led to the ability to perform SVT ablation with no or minimal fluoroscopy, with success and complication rates similar to standard techniques.147,149 152 Radiation exposure may be further reduced by using robotic or magnetic naviga- tion of catheters that use a 3-dimensional anatomic tracking system superimposed on traditional fluoroscopy imaging. A reduced- fluoroscopy approach is particularly important in pediatric patients and during pregnancy.153,154 2.5.4. Ablation Energy Sources Radiofrequency current is the most commonly used energy source for SVT ablation.155 Cryoablation is used as an alter- native to radiofrequency ablation to minimize injury to the AV node during ablation of specific arrhythmias, such as AVNRT, para-Hisian AT, and para-Hisian accessory path- ways, particularly in specific patient populations, such as children and young adults. Selection of the energy source Figure 4. Orthodromic atrioventricular reentrant tachycardia. Arrows point to the P waves, which are inscribed in the ST-segment after the QRS complex. The reentrant circuit involves anterograde conduction over the atrioventricular node, followed by retrograde conduction over an accessory pathway, which results in a retrograde P wave with short RP interval. Figure 5. Atrial tachycardia. Arrows point to the P wave, which is inscribed before the QRS complex. The focus of this atrial tachycardia was mapped during electrophysiological study to an area near the left inferior pulmonary vein. depends on operator experience, arrhythmia target location, and patient preference. Published trials, including a meta- analysis comparing radiofrequency ablation with cryoabla- tion for treatment of AVNRT, have shown a higher rate of recurrence with cryoablation but lower risk of permanent AV The rate of AVNRT recurrence with cryo- ablation depends on the size of the ablation electrode and the endpoint used.156,159 Ultimately, the choice of technol- ogy should be made on the basis of an informed discussion between the operator and the patient. 3. Sinus Tachyarrhythmias In normal individuals, the sinus rate at rest is generally between 50 bpm and 90 bpm, reflecting vagal tone.160 163 Sinus tachycardia refers to the circumstance in which the sinus rate exceeds 100 bpm. 