following questions should be addressed (see 'Approach to the patient' above): Is the arrhythmia causing symptoms or could it? Does the arrhythmia pose a risk to the patient? Does the arrhythmia require emergent cardioversion? Which arrhythmia is present? Does the patient require urgent hospitalization? Is specialist consultation required, and if so, how urgently? Should anticoagulation and/or other medical therapy be started? For patients who are symptomatic in the office, the management strategy will depend both on the characteristics of the symptoms and the type of arrhythmia present. In the following clinical scenarios, we recommend urgent transfer to a facility with emergency care capabilities (see 'Patients identified with an arrhythmia' above): Syncope or near syncope in patients with high degree AV block (ie, Mobitz type II second degree or third degree [complete] AV block) or bradycardia. Wide complex rhythms (other than sinus with bundle branch block) including ventricular tachycardia. https://www.uptodate.com/contents/arrhythmia-management-for-the-primary-care-clinician/print 13/34 7/6/23, 2:50 PM Arrhythmia management for the primary care clinician - UpToDate Patients in whom the diagnosis is uncertain after examination and ECG, but for whom there is a concern about a life-threatening arrhythmia. Patients with a history of heart disease (including coronary artery disease, cardiomyopathy, or heart failure) who present with syncope, near syncope, and/or documented ventricular arrhythmia. Sustained supraventricular tachycardia (SVT). Atrial fibrillation or flutter with rapid or slow rates. All antiarrhythmic drugs have the potential to increase ectopy or induce or aggravate monomorphic VT, torsades de pointes, ventricular fibrillation (VF), conduction disturbances, or bradycardia; this known as proarrhythmia ( table 3). We suggest the involvement of a specialist (cardiologist or electrophysiologist) when initiation of an antiarrhythmic drug is considered. (See 'Initiation of therapy' above.) The role of the PCC in the long-term care of patients with arrhythmias depends upon the particular arrhythmia diagnosis and treatment. All patients should be queried at each routine visit about changes in symptoms relevant to the arrhythmia and its treatment. ACKNOWLEDGMENT The UpToDate editorial staff acknowledges Leonard Ganz, MD, FHRS, FACC, who contributed to an earlier version of this topic review. Use of UpToDate is subject to the Terms of Use. REFERENCES 1. Shen WK, Sheldon RS, Benditt DG, et al. 2017 ACC/AHA/HRS Guideline for the Evaluation and Management of Patients With Syncope: A Report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines, and the Heart Rhythm Society. J Am Coll Cardiol 2017. 2. Zimetbaum PJ, Josephson ME. The evolving role of ambulatory arrhythmia monitoring in general clinical practice. Ann Intern Med 1999; 130:848. Topic 961 Version 26.0 https://www.uptodate.com/contents/arrhythmia-management-for-the-primary-care-clinician/print 14/34 7/6/23, 2:50 PM Arrhythmia management for the primary care clinician - UpToDate GRAPHICS Classification of cardiac arrhythmias Supraventricular Atrial origin Atrial fibrillation Atrial flutter Atrial tachycardia Ectopic focus (enhanced automaticity) Intraatrial or sinoatrial reentry Atrial extrasystoles (atrial premature beats) AV junction Atrioventricular nodal reentrant tachycardia Atrioventricular reentrant tachycardia AV junctional rhythms (enhanced automaticity) AV junctional extrasystoles Ventricular Ventricular tachycardia Sustained Nonsustained Ventricular fibrillation Ventricular extrasystoles (ventricular premature beats) Graphic 72601 Version 1.0 https://www.uptodate.com/contents/arrhythmia-management-for-the-primary-care-clinician/print 15/34 7/6/23, 2:50 PM Arrhythmia management for the primary care clinician - UpToDate ECG of polymorphic ventricular premature beats The ambulatory monitoring tracing demonstrates ventricular premature beats with 3 different morphologies, known as polymorphic ventricular premature beats; 1 ventricular couplet (2 successive premature beats) is also seen (arrow). The blocked P waves after the first and second premature beats (*) are due to concealed retrograde AV nodal conduction from the premature beat. ECG: electrocardiogram; VPBs: ventricular premature beats; AV: atrioventricular. Reproduced with permission by Samuel Levy, MD. Graphic 74977 Version 4.0 https://www.uptodate.com/contents/arrhythmia-management-for-the-primary-care-clinician/print 16/34 7/6/23, 2:50 PM Arrhythmia management for the primary care clinician - UpToDate ECG of sinus node dysfunction The continuous lead V2 rhythm strip shows evidence of sinus node dysfunction. Following the third sinus beat (*) there is a pause followed by the occurrence of an escape junctional rhythm at a slower rate. P waves reappear (arrows), which are initially dissociated from the QRS complex, but ultimately they become associated with the QRS, resulting in 1:1 conduction. Reproduced with permission by Samuel Levy, MD. Graphic 78649 Version 3.0 https://www.uptodate.com/contents/arrhythmia-management-for-the-primary-care-clinician/print 17/34 7/6/23, 2:50 PM Arrhythmia management for the primary care clinician - UpToDate Causes of bradycardia Intrinsic Extrinsic Idiopathic degenerative disorder Drugs Ischemic heart disease Antiarrhythmic agents Chronic ischemia Class IA - quinidine, procainamide Acute myocardial infarction Class IC - propafenone, flecainide Hypertensive heart disease Class II - -blockers Cardiomyopathy Class III - sotalol, amiodarone, dronedarone Trauma Class IV - diltiazem, verapamil Surgery for congenital heart disease Cardiac glycosides Heart transplant Antihypertensive agents Inflammation Clonidine, reserpine, methyldopa Collagen vascular disease Antipsychotic agents Rheumatic fever Lithium, phenothiazines, amitriptyline Pericarditis Autonomically mediated Infection Vasovagal syncope (cardioinhibitory) Viral myocarditis Carotid sinus hypersensitivity Lyme disease (Borrelia burgdorfer I) Hypothyroidism Neuromuscular disorder Intracranial hypertension Friedreich ataxia Hypothermia X-linked muscular dystrophy Hyperkalemia Familial disorder Hypoxia Anorexia nervosa Reproduced with permission from: Fuster V, Walsh R, Harrington R. Hurst's the Heart, 13th ed, McGraw-Hill Professional, New York 2010. Copyright 2010 The McGraw-Hill Companies, Inc. Graphic 65521 Version 11.0 https://www.uptodate.com/contents/arrhythmia-management-for-the-primary-care-clinician/print 18/34 7/6/23, 2:50 PM Arrhythmia management for the primary care clinician - UpToDate ECG of sustained monomorphic ventricular tachycardia Shown are the six precordial electrocardiogram (ECG) leads (V1-V6). The QRS complex is wide and bizarre and the rhythm is ventricular tachycardia (VT). The sixth (+) and seventh (*) QRS complexes show a change in morphology, resembling a normal QRS complex; these represent fusion beats, with partial (+) or complete (*) normalization of the QRS complex. The seventh QRS complex (*) is preceded by a distinct P wave, which is probably conducted, capturing the ventricle for one beat, but not terminating the VT; this is also known as a Dressler beat. Reproduced with permission by Samuel Levy, MD. Graphic 69201 Version 3.0 https://www.uptodate.com/contents/arrhythmia-management-for-the-primary-care-clinician/print 19/34 7/6/23, 2:50 PM Arrhythmia management for the primary care clinician - UpToDate Sustained ventricular tachycardia on ambulatory monitoring The ambulatory monitor in a patient being evaluated for syncope, which persisted after pacemaker insertion, shows sustained monomorphic ventricular tachycardia (SMVT) which terminates spontaneously. A brief period of ventricular pacing follows ventricular tachycardia termination. Reproduced with permission by Samuel Levy, MD. Graphic 54513 Version 2.0 https://www.uptodate.com/contents/arrhythmia-management-for-the-primary-care-clinician/print 20/34 7/6/23, 2:50 PM Arrhythmia management for the primary care clinician - UpToDate 12 lead ECG of atrial fibrillation The 12 lead ECG shows atrial fibrillation. The QRS complex is narrow, P waves are absent, and the baseline between successive QRS complexes shows irregular coarse "fibrillatory waves." The QRS complexes occur at irregularly irregular intervals. Reproduced with permission by Samuel Levy, MD. Graphic 64217 Version 2.0 https://www.uptodate.com/contents/arrhythmia-management-for-the-primary-care-clinician/print 21/34 7/6/23, 2:50 PM Arrhythmia management for the primary care clinician - UpToDate 12 lead ECG of atrial flutter The 12 lead electrocardiogram (ECG) of atrial flutter shows a regular rhythm with a narrow QRS complex. Flutter waves are present, best seen in leads II, III, and aVF (*). In this ECG, the flutter waves are negative in leads II, III, and aVF, and positive in lead V1. One flutter wave is obvious between the QRS complexes, while the second one is superimposed on the terminal portion of the QRS complex; hence there is 2:1 atrioventricular nodal block, which is the most common presentation for atrial flutter. Reproduced with permission by Samuel Levy, MD. Graphic 75931 Version 3.0 https://www.uptodate.com/contents/arrhythmia-management-for-the-primary-care-clinician/print 22/34 7/6/23, 2:50 PM Arrhythmia management for the primary care clinician - UpToDate ECG of atrial tachycardia with resultant paroxysmal complete AV block The continous lead II electrocardiogram (ECG) tracing initially shows a regular tachycardia at a rate of 160; the QRS complex is wide with a terminal S wave compatible with a right bundle branch block. There is gradual slowing of the rate with the development of atrioventricular (AV) nodal block; ultimately a series of nonconducted P waves (arrows) are seen and there is one escape ventricular premature beat (*). After a second ventricular premature beat (+), sinus rhythm is restored. Reproduced with permission by Samuel Levy, MD. Graphic 56931 Version 4.0 https://www.uptodate.com/contents/arrhythmia-management-for-the-primary-care-clinician/print 23/34 7/6/23, 2:50 PM Arrhythmia management for the primary care clinician - UpToDate Typical atrioventricular nodal reentrant tachycardia The first two complexes are normal sinus beats with a normal P wave followed by a QRS complex. The third complex, an atrial premature beat (APB), has a prolonged PR interval; it initiates a common or typical atrioventricular nodal reentrant tachycardia (AVNRT) in which antegrade conduction to the ventricle is via the slow pathway and retrograde atrial activation is by the fast pathway. Although no distinct P wave is seen, the QRS complex has a small terminal deflection, known as a pseudo r', which is the P wave superimposed upon the terminal portion of the QRS complex. Graphic 54290 Version 3.0 https://www.uptodate.com/contents/arrhythmia-management-for-the-primary-care-clinician/print 24/34 7/6/23, 2:50 PM Arrhythmia management for the primary care clinician - UpToDate II ECG of mobitz II second degree heart block The lead II rhythm strip shows four sinus beats with P wave followed by a QRS complex; the fifth P wave is not followed by a QRS complex and represents second degree heart block. There is no change in the PR interval prior to or after the blocked P wave and thus this is Mobitz II second degree heart block. A second episode of second degree heart block can be seen after the seventh QRS complex. Reproduced with permission by Samuel Levy, MD. Graphic 51492 Version 2.0 https://www.uptodate.com/contents/arrhythmia-management-for-the-primary-care-clinician/print 25/34 7/6/23, 2:50 PM Arrhythmia management for the primary care clinician - UpToDate Nonsustained ventricular tachycardia Nonsustained ventricular tachycardia in a patient with underlying atrial fibrillation. The ventricular arrhythmia consists of nine beats at an approximate rate of 170 beats/minute. Courtesy of Ary Goldberger, MD. Graphic 73299 Version 4.0 Normal rhythm strip Normal rhythm strip in lead II. The PR interval is 0.15 sec and the QRS duration is 0.08 sec. Both the P and T waves are upright. Courtesy of Morton F Arnsdorf, MD. Graphic 59022 Version 3.0 https://www.uptodate.com/contents/arrhythmia-management-for-the-primary-care-clinician/print 26/34 7/6/23, 2:50 PM Arrhythmia management for the primary care clinician - UpToDate Types of proarrhythmia during treatment with antiarrhythmic drugs (AADs) for atrial fibrillation or atrial flutter according to the Vaughan Williams Classification Ventricular proarrhythmia Torsade de pointes (Vaughan Williams class IA and type III drugs) Sustained monomorphic ventricular tachycardia (usually class IC drugs) Sustained polymorphic ventricular tachycardia/ventricular fibrillation without long QT interval (class IA, IC, and III drugs) Atrial proarrhythmia Provocation of recurrence (probably class IA, IC, and III drugs) Conversion of atrial fibrillation (AF) to atrial flutter (usually class IC drugs) with 1:1 conduction Increase of defibrillation threshold (a potential problem with class IC drugs) Abnormalities of conduction or impulse formation Accelerate ventricular rate during AF (class IA and type IC drugs) Accelerate conduction over accessory pathway (digoxin, type IV drugs) Sinus node dysfunction, atrioventricular block (almost all drugs) Vaughan Williams classification of AADs used for the treatment of atrial fibrillation or flutter Class IA - Disopyramide, procainamide, quinidine Class IC - Flecainide, propafenone Class III - Amiodarone, dofetilide, ibutilide, sotalol Class IV - Nondihydropyridine calcium channel blockers (diltiazem and verapamil) Data from Fuster V, Ryden LE, Cannom DS, et al. ACC/AHA/ESC guidelines for the management of patients with atrial brillation. A report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines and the European Society of Cardiology Committee for Practice Guidelines (Writing committee to revise the 2001 guidelines for the management of patients with atrial brillation). J Am Coll Cardiol 2006; 48:e149. Graphic 66133 Version 4.0 https://www.uptodate.com/contents/arrhythmia-management-for-the-primary-care-clinician/print 27/34 7/6/23, 2:50 PM Arrhythmia management for the primary care clinician - UpToDate Revised (2018) Vaughan Williams classification of antiarrhythmic drugs abridged table Class 0 (HCN channel blockers) Ivabradine Class I (voltage-gated Na+ channel blockers) Class Ia (intermediate dissociation): Quinidine, ajmaline, disopyramide, procainamide Class Ib (rapid dissociation): Lidocaine, mexilitine Class Ic (slow dissociation): Propafenone, flecainide Class Id (late current): Ranolazine Class II (autonomic inhibitors and activators) Class IIa (beta blockers): Nonselective: carvedilol, propranolol, nadolol Selective: atenolol, bisoprolol, betaxolol, celiprolol, esmolol, metoprolol Class IIb (nonselective beta agonists): Isoproterenol Class IIc (muscarinic M2 receptor inhibitors): Atropine, anisodamine, hyoscine, scopolamine Class IId (muscarinic M2 receptor activators): Carbachol, pilocarpine, methacholine, digoxin Class IIe (adenosine A1 receptor activators): Adenosine Class III (K+ channel blockers and openers) Class IIIa (voltage dependent K+ channel blockers): Ambasilide, amiodarone, dronedarone, dofetilide, ibutilide, sotalol, vernakalant Class IIIb (metabolically dependent K+ channel openers): https://www.uptodate.com/contents/arrhythmia-management-for-the-primary-care-clinician/print 28/34 7/6/23, 2:50 PM Arrhythmia management for the primary care clinician - UpToDate Nicorandil, pinacidil Class IV (Ca++ handling modulators) Class IVa (surface membrane Ca++ channel blockers): Bepridil, diltiazem, verapamil Class IVb (intracellular Ca++ channel blockers): Flecainide, propafenone Class V (mechanosensitive channel blockers): No approved medications Class VI (gap junction channel blockers) No approved medications Class VII (upstream target modulators) Angiotensin converting enzyme inhibitors Angiotensin receptor blockers Omega-3 fatty acids Statins HCN: hyperpolarization-activated cyclic nucleotide-gated; Na: sodium; K: potassium; Ca: calcium. Graphic 120433 Version 3.0 https://www.uptodate.com/contents/arrhythmia-management-for-the-primary-care-clinician/print 29/34 7/6/23, 2:50 PM Arrhythmia management for the primary care clinician - UpToDate Single lead electrocardiogram (ECG) showing polymorphic ventricular tachycardia (VT) This is an atypical, rapid, and bizarre form of ventricular tachycardia that is characterized by a continuously changing axis of polymorphic QRS morphologies. Graphic 53891 Version 5.0 https://www.uptodate.com/contents/arrhythmia-management-for-the-primary-care-clinician/print 30/34 7/6/23, 2:50 PM Arrhythmia management for the primary care clinician - UpToDate Single lead electrocardiogram (ECG) showing torsades de pointes The electrocardiographic rhythm strip shows torsades de pointes, a polymorphic ventricular tachycardia associated with QT prolongation. There is a short, preinitiating RR interval due to a ventricular couplet, which is followed by a long, initiating cycle resulting from the compensatory pause after the couplet. Graphic 73827 Version 4.0 https://www.uptodate.com/contents/arrhythmia-management-for-the-primary-care-clinician/print 31/34 7/6/23, 2:50 PM Arrhythmia management for the primary care clinician - UpToDate Example of torsades de pointes and ventricular flutter Shown are three ECG leads (I, II, III); bradycardia and prolongation of the QT interval are present. Several runs of polymorphic ventricular tachycardia, called torsades de pointes (TdP) when associated with QT prolongation are seen (panel A); after several minutes, a rapid sustained ventricular tachycardia, sometimes called ventricular flutter, occurs (panel B). This is closely related to ventricular fibrillation. Reproduced with permission by Samuel Levy, MD. Graphic 60231 Version 3.0 https://www.uptodate.com/contents/arrhythmia-management-for-the-primary-care-clinician/print 32/34 7/6/23, 2:50 PM Arrhythmia management for the primary care clinician - UpToDate Nonantiarrhythmic agents which may induce torsade de pointes Psychiatric drugs Antihistamines Phenothiazines - thioridazine, chlorpromazine Terfenadine Tricyclic antidepressants - amitriptyline Astemizole Haloperidol Calcium channel blockers Antibiotics Bepridil Azithromycin Lidoflazine Chloroquine Antihyperlipidemics Erythromycin Probucol Pentamidine Other Trimethoprim-sulfamethoxazole Amantadine Toxins Cisapride Arsenic Organophosphate insecticides Diuretics Graphic 72631 Version 2.0 https://www.uptodate.com/contents/arrhythmia-management-for-the-primary-care-clinician/print 33/34 7/6/23, 2:50 PM Arrhythmia management for the primary care clinician - UpToDate Contributor Disclosures Samuel L vy, MD No relevant financial relationship(s) with ineligible companies to disclose. Brian Olshansky, MD Other Financial Interest: AstraZeneca [Member of the DSMB for the DIALYZE trial]; Medtelligence [Cardiovascular disease]. All of the relevant financial relationships listed have been mitigated. Hugh Calkins, MD Grant/Research/Clinical Trial Support: Adagio Medical [Atrial fibrillation]; Boston Scientific [ARVC]; Farapulse [Atrial fibrillation]; Medtronic [Atrial fibrillation]. Consultant/Advisory Boards: Abbott [Atrial fibrillation]; Atricure [Atrial fibrillation]; Biosense Webster [Catheter ablation]; Boston Scientific [ARVC and atrial fibrillation]; Medtronic [Atrial fibrillation]; Sanofi [Atrial fibrillation]. Other Financial Interest: Atricure [Lecture honoraria]; Biosense Webster [Lecture honoraria]; Boston Scientific [Lecture honoraria]; Medtronic [Lecture honoraria]. All of the relevant financial relationships listed have been mitigated. Susan B Yeon, MD, JD, FACC No relevant financial relationship(s) with ineligible companies to disclose. Contributor disclosures are reviewed for conflicts of interest by the editorial group. When found, these are addressed by vetting through a multi-level review process, and through requirements for references to be provided to support the content. Appropriately referenced content is required of all authors and must conform to UpToDate standards of evidence. Conflict of interest policy https://www.uptodate.com/contents/arrhythmia-management-for-the-primary-care-clinician/print 34/34