7/6/23, 11:10 AM Arrhythmia-induced cardiomyopathy - UpToDate Official reprint from UpToDate www.uptodate.com 2023 UpToDate, Inc. and/or its affiliates. All Rights Reserved. Arrhythmia-induced cardiomyopathy : Cynthia M Tracy, MD : William J McKenna, MD : Todd F Dardas, MD, MS All topics are updated as new evidence becomes available and our peer review process is complete. Literature review current through: Jun 2023. This topic last updated: May 24, 2022. INTRODUCTION Cardiomyopathies are diseases of the heart muscle, inclusive of a variety of myocardial disorders that manifest with various structural and functional phenotypes and are frequently genetic. Although some have defined cardiomyopathy to include myocardial disease caused by known cardiovascular causes (such as hypertension, ischemic heart disease, or valvular disease), current major society definitions of cardiomyopathy exclude heart disease secondary to such cardiovascular disorders [1,2]. (See "Definition and classification of the cardiomyopathies" and "Causes of dilated cardiomyopathy".) The prognosis in patients with dilated cardiomyopathy is variable and dependent on the cause; importantly, there are some etiologies that may improve or resolve following treatment. One such cause is an arrhythmia-induced cardiomyopathy (also known as tachycardia-induced cardiomyopathy, tachycardia-mediated cardiomyopathy, and tachymyopathy), a relatively rare though well-recognized entity caused by long-standing tachycardia, which in most instances is readily treatable with a good prognosis [3]. Arrhythmia-induced cardiomyopathy has been reported with nearly all types of tachyarrhythmias and frequent ectopy, both supraventricular and ventricular [4]. A common clinical problem is determining whether the tachycardia is the primary cause of the patient's cardiomyopathy, or if the tachycardia is secondary to a cardiomyopathy of different etiology. This topic will discuss arrhythmia-induced cardiomyopathy as a primary cause of cardiomyopathy. Arrhythmias occurring in the setting of a specific cardiomyopathy are discussed separately. (See "Hypertrophic cardiomyopathy in adults: Supraventricular https://www.uptodate.com/contents/arrhythmia-induced-cardiomyopathy/print 1/29 7/6/23, 11:10 AM Arrhythmia-induced cardiomyopathy - UpToDate tachycardias including atrial fibrillation" and "Hypertrophic cardiomyopathy: Risk stratification for sudden cardiac death" and "Arrhythmogenic right ventricular cardiomyopathy: Anatomy, histology, and clinical manifestations", section on 'Ventricular arrhythmias'.) EPIDEMIOLOGY While the exact incidence of arrhythmia-induced cardiomyopathy remains unclear, an association between tachycardia and cardiomyopathy has been recognized for some time [5-8]. Virtually every form of supraventricular tachyarrhythmia, including ectopic atrial tachycardia (AT), nonparoxysmal junctional tachycardia, and atrial fibrillation (AF), has been associated with reversible left ventricular (LV) dysfunction or "cardiomyopathy." The development of a cardiomyopathy has also been documented with ventricular tachyarrhythmias and frequent ectopic beats [9-11]. (See "Hemodynamic consequences of atrial fibrillation and cardioversion to sinus rhythm" and 'Frequent ectopic beats' below.) Some insight into the prevalence of arrhythmia-induced cardiomyopathy can be derived from cohort studies of patients undergoing catheter ablation for symptomatic arrhythmias. As examples: Among a cohort of 331 patients who were referred for catheter ablation of incessant AT, myocardial dysfunction was present in 9 percent of patients [12]. Patients with an arrhythmia-induced cardiomyopathy were younger (mean age 39 versus 51 years), more frequently male (60 versus 38 percent), and had incessant or very frequent paroxysmal tachycardia (100 versus 20 percent). Among a cohort of 625 patients undergoing catheter ablation for a variety of tachyarrhythmias, a tachycardia-induced cardiomyopathy was present in 2.7 percent (17 of 625 patients) [13]. Among a cohort of 1269 patients undergoing ablation for atrial flutter, 184 had reduced LV ejection fraction (LVEF; <40 percent) at baseline [14]. PATHOPHYSIOLOGY Chronic tachycardia ultimately produces significant cardiac structural changes, including LV dilation and cellular morphologic changes [15-19]. However, the exact mechanism by which tachycardia produces these changes is not well defined. https://www.uptodate.com/contents/arrhythmia-induced-cardiomyopathy/print 2/29 7/6/23, 11:10 AM Arrhythmia-induced cardiomyopathy - UpToDate Animal models, initially developed in the general investigation of heart failure (HF), have been studied extensively in the evaluation of arrhythmia-induced cardiomyopathy. Rapid pacing produces changes in animals that are similar to those observed in humans, including a marked depression of LVEF, elevated filling pressures, depressed cardiac output, and increased systemic vascular resistance [16-18,20-24]. These changes are generally reversible with cessation of the tachycardia, although in some cases LVEF may not return to baseline [24,25]. Similar findings have been reported in an animal model following the delivery of premature ventricular complexes/contractions (PVCs; also referred to as premature ventricular beats or premature ventricular depolarizations) in a bigeminal pattern for 12 weeks, which resulted in LV dilation and reduction in LVEF [26]. The morphologic and biochemical changes that result from an arrhythmia-induced cardiomyopathy also may produce electrophysiologic abnormalities. In a canine model, chronic tachycardia was associated with ventricular arrhythmias (including polymorphic ventricular tachycardia [VT] and sudden death) that result from a prolongation in repolarization [27]. Many alterations in neurohumoral and cellular activation have been described, and several factors probably contribute to the development of rate-related myocardial dysfunction. Although data supporting certain potential mechanisms are compelling, it remains unclear whether they play an etiologic role or if they arise as a consequence of tachycardia. Depletion of myocardial energy stores and myocardial ischemia Studies in animal models have shown that persistent tachycardia depletes high-energy stores as evidenced by reduced myocardial levels of creatine, phosphocreatine, and adenosine triphosphate (ATP), and diminished activity of the Na-K-ATPase pump [28-30]. These changes are probably due to alterations in cellular metabolism with mitochondrial injury and increased activity of Krebs cycle oxidative enzymes [15,20]. Myocardial ischemia may play a role in the development of arrhythmia-induced cardiomyopathy. Similar depletions in high-energy stores are seen in ischemic models following vessel occlusion, situations where high-energy stores are rapidly depleted and LV dysfunction occurs [31,32]. High-energy stores return to normal within days after the ischemic insults. Tachycardia-induced depletion of high-energy stores, which may be mediated in part by ischemia, is reversible and may explain the reversibility of this cardiomyopathy. Abnormalities in subendocardial to subepicardial flow ratios and impaired coronary flow have been found in arrhythmia-induced cardiomyopathy [33-36]. The impaired coronary https://www.uptodate.com/contents/arrhythmia-induced-cardiomyopathy/print 3/29 7/6/23, 11:10 AM Arrhythmia-induced cardiomyopathy - UpToDate blood flow occurs in association with elevation in cardiac filling pressures and impaired LV diastolic function [25,37,38]. Abnormal calcium handling and beta adrenergic responsiveness Abnormalities in both calcium channel activity and sarcoplasmic reticulum calcium transport may contribute to the myocardial dysfunction in arrhythmia-induced cardiomyopathy [20,35]. Diminished beta-adrenergic responsiveness has also been described and may be due to reduced myocyte beta-1 receptor density (downregulation) [37,39,40]. The reduction in beta receptor density and responsiveness is independent of hemodynamic and neurohumoral factors [41]. Oxidative stress and injury In patients with AF and atrial dysfunction, there is histologic evidence of oxidative stress and injury in the atrial myocardium [42]. This results in peroxynitrite formation, which modifies myofibrillar proteins, contributes to loss of fibrillar protein function, and alters myofibrillar energetics. Support for the role of oxidative stress comes from one animal study which found that the administration of the antioxidant vitamins E, C, and beta-carotene attenuated the cardiac dysfunction and prevented beta receptor downregulation produced by rapid cardiac pacing [43]. Genetic basis and ACE gene polymorphism An association has been reported between a gene polymorphism and arrhythmia-induced cardiomyopathy. Levels of angiotensin converting enzyme (ACE) are associated with a 287 base pair insertion (I)/deletion (D) polymorphism in intron 16 of the ACE gene. The DD genotype is associated with increased serum ACE levels and a higher incidence of both ischemic and idiopathic dilated cardiomyopathy. In a study comparing 20 patients with arrhythmia-induced cardiomyopathy, 20 controls with persistent tachycardia but normal LV function, and 24 normal volunteers, the DD genotype was significantly more common in the patients with arrhythmia-induced cardiomyopathy [44]. Histopathologic and immunologic findings Among a cohort of 189 patients with new onset HF and reduced LVEF not related to valvular or ischemic heart disease, 19 patients met criteria for tachycardia-induced cardiomyopathy. Endomyocardial biopsies in the tachycardia-induced cardiomyopathy patients showed a stronger myocardial expression of + major histocompatibility complex class II molecule and enhanced infiltration of CD68 macrophages compared with patients with idiopathic dilated cardiomyopathy. Compared to patients with ischemic cardiomyopathy, those with tachycardia induced cardiomyopathy had fewer T cells and macrophages. Fibrosis was also less prominent in the tachycardia https://www.uptodate.com/contents/arrhythmia-induced-cardiomyopathy/print 4/29 7/6/23, 11:10 AM Arrhythmia-induced cardiomyopathy - UpToDate induced cardiomyopathy patients. However, electron microscopy in these patients showed abnormal mitochondrial distribution and enhanced myocyte size. RNA expression analysis showed alterations in metabolic pathways [45]. ARRHYTHMIAS ASSOCIATED WITH ARRHYTHMIA-INDUCED CARDIOMYOPATHY A number of tachyarrhythmias have been associated with arrhythmia-induced cardiomyopathy, including AF, atrial flutter, atrial tachycardia (AT), reentrant supraventricular tachycardias, and VT [11,46-60]. In addition, very frequent ectopic beats, both atrial and ventricular, have been associated with arrhythmia-induced cardiomyopathy. Regardless of the arrhythmia, therapy to restore normal sinus rhythm or to slow the ventricular rate (or eliminate ectopy) appears to result in an improvement in LV function ( table 1). However, most descriptive series include only a small number of patients. Supraventricular arrhythmias Atrial fibrillation and atrial flutter Epidemiologic studies have shown that patients with AF are at increased risk for HF [61]. In some patients, restoration of sinus rhythm or control of the rapid ventricular rate markedly improves or even normalizes the LVEF, indicating that the LV dysfunction was primarily due to the rapid AF rather than another etiology. Improvement in LV function is seen with both rhythm and rate control, although it may be more likely with rhythm control. (See "Hemodynamic consequences of atrial fibrillation and cardioversion to sinus rhythm".) There is an association between HF and AF, and it is often not possible to determine which is causative. Nevertheless, an estimated 25 to 50 percent of patients with LV dysfunction and AF have some component of arrhythmia-induced cardiomyopathy [4,62-64]. There are less data on the frequency and predictors of arrhythmia-induced cardiomyopathy in patients with atrial flutter. In one study of patients undergoing ablation for atrial flutter, 25 percent had evidence for cardiomyopathy prior to ablation [65]. Of these, 57 percent had significant improvement in their LVEF postablation. The only predictor of reversibility of cardiomyopathy in this study was average heart rate. Similarly, in a cohort of 1269 patients undergoing ablation for atrial flutter, 184 had reduced LVEF (<40 percent) at baseline. Of these patients with reduced LVEF, 103 patients (56 percent) had marked improvement in LVEF at six months. Those who experienced improvement in the LVEF had similar survival to patients who https://www.uptodate.com/contents/arrhythmia-induced-cardiomyopathy/print 5/29 7/6/23, 11:10 AM Arrhythmia-induced cardiomyopathy - UpToDate did not have baseline depressed LVEF. Those whose LVEF failed to improve had a three-fold higher mortality [14]. Atrial tachycardia Incessant AT, an infrequent cause of symptomatic supraventricular tachyarrhythmia, can cause myocardial dysfunction in approximately 10 percent of patients [12]. Children are more likely than adults to present with arrhythmia-induced cardiomyopathy due to incessant AT. When AT is seen in adults, it is more commonly associated with another cardiac problem, and distinguishing the effect of tachycardia from that of the underlying cardiac disease may be difficult. (See "Focal atrial tachycardia", section on 'Incessant AT resulting in cardiomyopathy' and "Atrial tachyarrhythmias in children", section on 'Atrial ectopic tachycardia and focal atrial tachycardia'.) Incessant AT and ectopic AT have been associated with the development of cardiomyopathy that can be reversed with restoration of sinus rhythm [46-52]. Improved techniques for catheter ablation frequently permit definitive therapy for AT, which can lead to the resolution of myocardial dysfunction with a high degree of success [12,46,52]. (See "Focal atrial tachycardia", section on 'Treatment of incessant AT'.) Reentrant supraventricular tachycardias Reentrant supraventricular tachycardias, including atrioventricular nodal reentrant tachycardia (AVNRT) and atrioventricular reciprocating tachycardia (AVRT), are more commonly paroxysmal but can cause a persistent tachycardia. Cases of arrhythmia-induced cardiomyopathy have been described with persistent junctional reciprocating tachycardia, accessory pathway mediated tachycardia (ie, AVRT) and AVNRT [50,54- 57]. In the absence of other factors, the cardiomyopathy related to an incessant reentrant supraventricular tachycardia is reversible following catheter ablation [55]. (See "Atrioventricular reentrant tachycardia (AVRT) associated with an accessory pathway" and "Atrioventricular nodal reentrant tachycardia".) Ventricular arrhythmias Only rare reports have described reversible cardiomyopathy related to VT, since this arrhythmia is usually associated with some form of underlying structural heart disease. However, idiopathic LV tachycardia or right ventricular outflow tract VT can arise in structurally normal hearts [9,10,54]. In rare cases, these arrhythmias are persistent or repetitive enough to result in a cardiomyopathy. In one study of patients with repetitive monomorphic VT and/or premature ventricular complexes/contractions (PVCs), an arrhythmia-induced cardiomyopathy was seen in 9 percent, all of which improved with treatment [66]. Similar to supraventricular arrhythmias, the myopathy usually reverses following ablation of the arrhythmia [58]. (See "Ventricular tachycardia in the absence of apparent structural heart disease".) https://www.uptodate.com/contents/arrhythmia-induced-cardiomyopathy/print 6/29 7/6/23, 11:10 AM Arrhythmia-induced cardiomyopathy - UpToDate Unlike monomorphic VT, which can be present and hemodynamically stable for extended periods of time, polymorphic VT, which is generally an unstable rhythm, and ventricular fibrillation, a non-perfusing rhythm, are not associated with arrhythmia-induced cardiomyopathy. Frequent ectopic beats Frequent ventricular ectopy Very frequent ventricular ectopy in the form of PVCs has been associated with a reversible cardiomyopathy, even in the absence of sustained ventricular arrhythmias [11,59,66-74]. While most earlier studies defined "frequent" as greater than 10 percent of overall heartbeats, in contemporary practice a cutoff of >15 percent of all heartbeats is more commonly used. Although some patients with similarly high PVC burdens can maintain normal cardiac function, PVC-induced cardiomyopathy has also been reported in patients with PVC burdens as low as 4 to 5 percent. In a prospective observational cohort study of 80 patients (59 percent male, mean age 53 years) with frequent PVCs (mean PVC burden 22 percent) and reduced LVEF ( 50 percent) who underwent catheter ablation, 53 patients (66 percent) had successful long-term elimination of PVCs, with significant improvement in LVEF and New York Heart Association (NYHA) functional class [70]. In a 2014 systematic review and meta-analysis of radiofrequency ablation for the treatment of idiopathic PVCs originating from the right ventricular outflow tract, catheter ablation was associated with a significant improvement in LVEF, though the meta-analysis was limited by significant heterogeneity among the studies [75]. (See "Premature ventricular complexes: Treatment and prognosis".) In addition to the overall frequency of PVCs, QRS duration, epicardial site of origin of PVCs, and resulting dyssynchrony all appear to play a role in the development of cardiomyopathy and are associated with outcomes following catheter ablation. Greater dyssynchrony increases the risk of cardiomyopathy, wider QRS complexes appear more likely to result in cardiomyopathy with a lower overall burden of PVCs while also being associated with longer times to normalization of LV systolic function following ablation, and epicardial PVC origin also appears to predict delayed LV function recovery [74,76-80]. Frequent atrial ectopy Premature atrial complexes (PACs; also referred to as premature atrial beats, premature supraventricular complexes, or premature supraventricular beats) are usually benign, but a high burden of PACs has been associated with a reversible cardiomyopathy [81,82]. https://www.uptodate.com/contents/arrhythmia-induced-cardiomyopathy/print 7/29 7/6/23, 11:10 AM Arrhythmia-induced cardiomyopathy - UpToDate CLINICAL PRESENTATION The clinical presentation of arrhythmia-induced cardiomyopathy is variable but usually involves signs and/or symptoms related to the tachyarrhythmia (eg, palpitations, dyspnea, chest discomfort, etc), HF (eg, dyspnea, edema, weight gain, orthopnea, etc), or both. In our experience, HF symptoms are more common since patients with symptomatic tachyarrhythmias will frequently seek medical attention earlier in the course of their care and prior to the development of a cardiomyopathy. The approach to the patient with suspected arrhythmia- induced cardiomyopathy includes a thorough history and physical examination, with appropriately selected tests to establish the diagnosis and assess acuity, severity, and etiology. Several professional societies have issued recommendations for the evaluation of patients with suspected HF or cardiomyopathy [83-86]. Signs and symptoms The clinical presentation of arrhythmia-induced cardiomyopathy is variable but usually involves symptoms of palpitations or HF. Patients may present with palpitations or other symptom (eg, dyspnea, chest discomfort) related to the rapidity or irregularity of their arrhythmia. However, those with more rapid heart rates typically present with symptoms related to the inappropriate heart rate before enough time has elapsed to result in a cardiomyopathy. In contrast, patients with tachycardia but a relatively slower heart rate and no obvious symptoms may have little or no awareness of the arrhythmia. While such patients without palpitations are occasionally discovered during a routine medical exam for other reasons, typically they present with fatigue, decreased exercise tolerance, or symptomatic HF. Given that patients with more rapid heart rates often present earlier with symptoms related to the tachycardia, some investigators have hypothesized that patients with atrial arrhythmias who subsequently develop arrhythmia-induced cardiomyopathy have slower overall heart rates than patients who do not develop arrhythmia-induced cardiomyopathy. Published reports in both adult and pediatric populations support this hypothesis: In a retrospective cohort study of 331 patients who had undergone ablation for atrial tachycardia (AT), among whom 9 percent presented with evidence of arrhythmia-induced cardiomyopathy, those with arrhythmia-induced cardiomyopathy had slower ventricular heart rates during tachycardia compared with patients who did not have arrhythmia- induced cardiomyopathy (120 versus 149 beats per minute) [12]. (See "Focal atrial tachycardia", section on 'Incessant AT resulting in cardiomyopathy'.) In a retrospective cohort study of 16 pediatric patients with focal AT, those with AT arising from the atrial appendages were more likely to be asymptomatic at presentation, more https://www.uptodate.com/contents/arrhythmia-induced-cardiomyopathy/print 8/29 7/6/23, 11:10 AM Arrhythmia-induced cardiomyopathy - UpToDate likely to have a ventricular heart rate less than 120 beats per minute, and more commonly presented with arrhythmia-induced cardiomyopathy [87]. ECG findings All patients should have an electrocardiogram (ECG) to document the cardiac rhythm and ventricular heart rate. Whenever possible, obtaining prior ECGs can be extremely helpful to determine whether ambiguous P wave morphologies are related to the sinus node (as seen on prior tracings) versus an ectopic atrial focus. There are no specific ECG findings that distinguish patients with and without arrhythmia-induced cardiomyopathy, and the ECG findings will vary depending upon the underlying tachyarrhythmia. However, by definition, all patients with an arrhythmia-induced cardiomyopathy should have a heart rate greater than 100 beats per minute. APPROACH TO THE DIAGNOSIS Arrhythmia-induced cardiomyopathy is defined by the presence of a sustained tachycardia (or frequent episodes of tachycardia or very frequent ectopy) which results in LV systolic dysfunction. Determining which of the pathologies (the arrhythmia or the cardiomyopathy) is the primary pathologic process is key to establishing the diagnosis. Usually the diagnosis of arrhythmia-induced cardiomyopathy can only be made following a successful trial of therapy to slow the ventricular rate or to restore sinus rhythm along with the exclusion of other potential causes of cardiomyopathy. Patients in whom arrhythmia-induced cardiomyopathy is suspected should undergo continuous cardiac monitoring for 24 to 48 hours and have non-invasive imaging to assess cardiac structure and function. For most patients, a transthoracic echocardiogram is the preferred test for assessing cardiac structure and function due to its widespread availability and ease of performance; however, cardiovascular magnetic resonance (CMR) imaging is a reasonable alternative approach in centers with expertise in this modality. DIAGNOSTIC TESTING Once arrhythmia-induced cardiomyopathy is suspected, appropriately selected tests can help to establish the diagnosis. All of the following are performed as part of the initial evaluation. Cardiac monitoring Heart rate over time should be continuously measured for 24 to 48 hours using inpatient telemetry or ambulatory (Holter) monitoring to document the average heart rate and, in some cases, provide additional information on the underlying rhythm [88]. A sustained heart rate greater than 100 beats per minute, and particularly greater than 120 beats https://www.uptodate.com/contents/arrhythmia-induced-cardiomyopathy/print 9/29 7/6/23, 11:10 AM Arrhythmia-induced cardiomyopathy - UpToDate per minutes, is consistent with arrhythmia-induced cardiomyopathy. Because of the potential reversible nature of arrhythmia-induced cardiomyopathy, if uncertainty persists regarding the cardiac rhythm, full invasive electrophysiologic studies may be necessary to establish the underlying cardiac rhythm and guide the optimal therapy. (See 'Treatment' below and "Invasive diagnostic cardiac electrophysiology studies".) Assessment of cardiac structure and function All patients with suspected arrhythmia- induced cardiomyopathy should undergo an assessment of cardiac structure and function to document LV size and function, in particular LVEF. Transthoracic echocardiography is the most common and widespread test for documenting cardiac structure and function, but CMR imaging is an alternative approach. While there are no absolute echocardiographic parameters that can distinguish arrhythmia-induced cardiomyopathy from other forms of dilated cardiomyopathy, in general, the LV end-diastolic dimension tends to be smaller in patients with arrhythmia-induced cardiomyopathy [4,89]. In patients with improved LVEF after treatment of an arrhythmia, CMR may be useful for the evaluation of cardiac structure and function. Patients who have a CMR that demonstrates a low LVEF or late gadolinium enhancement have incomplete resolution of cardiac injury [90]. Alternatively, in assessing the underlying cause of arrhythmia-induced cardiomyopathy, patients in one study with frequent premature ventricular complexes/contractions (PVCs) who failed to improve LVEF after treatment were found to have late gadolinium enhancement on CMR, and likely the cause of the cardiomyopathy was not purely tachycardia mediated [91]. Studies have suggested the use of two-dimensional strain echocardiography as a tool to predict recovery from arrhythmia induced cardiomyopathy [92]. In a study of 71 patients with presumed tachycardia-induced cardiomyopathy, a lower LVEF at baseline and higher relative apical longitudinal strain ratio (RALSR) were associated with no recovery in LVEF during follow-up. However, by multivariate analysis the RALSR was found to be a significant predictor of functional recovery after the arrhythmia was treated. Excluding other causes of cardiomyopathy Patients with newly diagnosed HF and/or cardiomyopathy require an assessment for genetic and other causes of LV dysfunction and exclusion of significant underlying coronary heart disease (CHD). Decisions on the initial use of stress testing or coronary angiography should be made based on the presence or absence of symptoms suggestive of CHD and the individual patient's likelihood of CHD. The differential diagnosis of dilated cardiomyopathy, and the approach to excluding CHD, are discussed in greater detail separately. While patients with HF and cardiomyopathies of other etiologies may exhibit rapid heart rates (eg, persistent sinus tachycardia), this can usually be distinguished from an arrhythmia-induced cardiomyopathy by comparison of ECG findings over time (eg, sinus P https://www.uptodate.com/contents/arrhythmia-induced-cardiomyopathy/print 10/29 7/6/23, 11:10 AM Arrhythmia-induced cardiomyopathy - UpToDate wave morphology) and response to treatment. An important part of the evaluation is a careful review of the family history, and when the phenotype is clear, genetic testing should be recommended. Several of the genetically determined arrhythmogenic cardiomyopathies can present with frequent ectopy (PVCs, nonsustained VT, and/or AF in association with LV dilation and/or impaired function, eg, desmoplakin, filamin C, lamin AC, desmin) [93,94]. (See "Causes of dilated cardiomyopathy" and "Determining the etiology and severity of heart failure or cardiomyopathy", section on 'Detection of coronary artery disease'.) TREATMENT The initial treatments for a patient with HF and suspected arrhythmia-induced cardiomyopathy are the same as those used in most other patients with HF with reduced ejection fraction (eg, angiotensin converting enzyme [ACE] inhibitors or angiotensin II receptor blockers [ARBs], beta blockers, diuretics) and tachyarrhythmias (eg, rate-control medications, consideration of antiarrhythmic drugs and/or cardioversion). However, because of the potentially reversible nature of arrhythmia-induced cardiomyopathy, efforts should be made to achieve adequate ventricular heart rate control or to restore sinus rhythm [4]. Additionally, given the potentially reversible nature of this condition, an adequate trial of therapy is required prior to assessment of the need for cardiac resynchronization therapy or an implantable cardioverter-defibrillator. (See "Cardiac resynchronization therapy in heart failure: Indications and choice of system" and "Primary prevention of sudden cardiac death in patients with cardiomyopathy and heart failure with reduced LVEF" and "Overview of the management of heart failure with reduced ejection fraction in adults", section on 'Pharmacologic therapy'.) Patients with atrial fibrillation or flutter For patients in whom AF or atrial flutter is the suspected cause of cardiomyopathy, the initial approach to management is similar to other patients with HF and includes prompt rate control with AV nodal blockers and appropriate anticoagulation. (See "The management of atrial fibrillation in patients with heart failure".) Beyond these initial steps, controversy still exists as to whether rate control or rhythm control is the optimal therapy for AF- or atrial flutter-induced cardiomyopathy. Our strategy for management is as follows: For minimally symptomatic patients with AF in whom adequate rate control is achieved, we continue medical therapy. In patients with a cardiomyopathy whose origin is suspected to be AF or atrial flutter, heart rate control through either rate control or rhythm control can be effective at improving cardiac function [95-98]. https://www.uptodate.com/contents/arrhythmia-induced-cardiomyopathy/print 11/29 7/6/23, 11:10 AM Arrhythmia-induced cardiomyopathy - UpToDate For patients with AF who remain significantly symptomatic or in whom adequate rate control is not achieved with medical therapy alone, we pursue a rhythm control strategy. For patients with atrial flutter, rapid ventricular rates, and newly recognized LV systolic function, rate control may be difficult to achieve with medication; in these patients, we perform early electrical cardioversion. Management of AF and/or atrial flutter is geared towards avoidance of thromboembolic events, reduction of symptoms, and avoidance of arrhythmia-induced cardiomyopathy. Control of heart rate can be met through either a rate control strategy with atrioventricular (AV) nodal blocking agents (or ablation and pacer implant in cases of multiple drug failures) or through maintenance of sinus rhythm (rhythm control strategy). Strategies for rate control versus rhythm control are discussed elsewhere, and choices of agents are dictated by cardiac structure, underlying pathology, and function. (See "Atrial fibrillation: Overview and management of new-onset atrial fibrillation" and "Restoration of sinus rhythm in atrial flutter", section on 'Indications' and "Management of atrial fibrillation: Rhythm control versus rate control".) At initial presentation of the patient with rapid ventricular rates and newly recognized depressed EF, the concern exists that at least some component is related to arrhythmia-induced cardiomyopathy. This is particularly suspected in younger patients with severe symptoms from the AF. A trial of early cardioversion is warranted in these patients with subsequent monitoring for improvement in cardiac function [99]. Patients with another SVT For supraventricular tachyarrhythmias (SVTs) other than AF or atrial flutter that result in arrhythmia-induced cardiomyopathy, restoration of sinus rhythm is the usual goal. Options for the restoration of sinus rhythm include electrical cardioversion, antiarrhythmic drugs, and catheter ablation of the arrhythmia. The initial choice of modality will vary depending upon the underlying SVT as well as the local expertise and availability of options (ie, some centers do not perform catheter ablation) but should be made in conjunction with an electrophysiologist experienced in the treatment of sustained tachyarrhythmias. Certain SVTs are more amenable to electrical cardioversion (eg, atrioventricular nodal reentrant tachycardia), while others are often refractory or recurrent following cardioversion (eg, atrial tachycardia). Often, atrial arrhythmias can be refractory to antiarrhythmics, and AV nodal blocking agents may be required in high doses to achieve appropriate heart rates. In patients with depressed LVEF, it is important to avoid agents that have a higher likelihood of proarrhythmia (eg, flecainide) or that could further depress LVEF (eg, disopyramide). If an ablation is performed, close follow-up is required even after successful ablation because of the tendency for cardiomyopathy to recur if tachycardia recurs. (See "Focal atrial tachycardia", https://www.uptodate.com/contents/arrhythmia-induced-cardiomyopathy/print 12/29 7/6/23, 11:10 AM Arrhythmia-induced cardiomyopathy - UpToDate section on 'Catheter ablation' and "Treatment of arrhythmias associated with the Wolff- Parkinson-White syndrome", section on 'Catheter ablation' and "Atrial tachyarrhythmias in children", section on 'Management' and "Atrioventricular nodal reentrant tachycardia", section on 'Catheter ablation'.) Patients with frequent ectopy For patients presenting with a high burden of premature ventricular complexes/contractions (PVCs) and newly recognized cardiomyopathy, initial management is to look for underlying causes (such as CAD, valvular heart disease, arrhythmogenic right ventricular dysplasia [ARVD], etc) and initiation of guideline-based optimal medical therapy for HF [100]. Correction of electrolytes and initiation of beta blockers are typical first therapies. (See "Overview of the management of heart failure with reduced ejection fraction in adults".) Given the possibility of arrhythmia-induced cardiomyopathy in patients with a high PVC burden (eg, >15 to 20 percent of total beats on a 24-hour ambulatory monitor) and associated with LV dysfunction, we generally pursue radiofrequency catheter ablation [100-102]. Catheter ablation of high-frequency PVCs has emerged as a safe and effective therapy and may be considered if medical management is ineffective or poorly tolerated and depending on patient preference [59,74,103-105]. While it is not possible to specify an exact percentage (PVC burden) for which a patient might benefit from ablation of frequent PVCs as studies have had a wide range in their inclusion criteria, consideration may be given with a burden of above 10 percent, but our approach is typically to offer ablation at a higher burden (eg, >15 to 20 percent PVCs). The approach to catheter ablation in patients with a high PVC burden is discussed in greater detail separately. (See "Ventricular arrhythmias: Overview in patients with heart failure and cardiomyopathy" and "Premature ventricular complexes: Treatment and prognosis", section on 'Catheter ablation'.) Patients with refractory tachyarrhythmias In the event that a supraventricular arrhythmia is likely the cause of cardiomyopathy and cannot be primarily ablated, AV node ablation with either biventricular pacing or conduction system pacing is a reasonable approach to management. While there are no studies that specifically address the strategy of AV nodal ablation and biventricular pacemaker placement in patients with arrhythmia-induced cardiomyopathy, there is indirect evidence to support this approach. In a trial that included patients with HF, a narrow QRS, and permanent AF but who did not explicitly have arrhythmia-induced cardiomyopathy, patients assigned to medical rate control had a higher risk of death or rehospitalization due to HF or worsening of HF when compared with patients assigned to AV node ablation and cardiac https://www.uptodate.com/contents/arrhythmia-induced-cardiomyopathy/print 13/29 7/6/23, 11:10 AM Arrhythmia-induced cardiomyopathy - UpToDate resynchronization therapy (38 versus 10 percent; hazard ratio 0.28, 95% CI 0.11-0.72) [106]. The effect of this approach on recovery of LVEF was not reported. Other trials and studies of patients with preexisting AV node block, HF, and various causes of LV systolic dysfunction are discussed elsewhere. (See "Cardiac resynchronization therapy in heart failure: Indications and choice of system".) FOLLOW-UP Whereas the initial cardiomyopathy may have taken months to develop, recurrent tachycardia can lead to an abrupt decline in LVEF. Diastolic dysfunction can persist even after systolic function has normalized and can lead to decreased coronary flow reserve. In patients who develop a recurrence of the arrhythmia, the increased myocardial oxygen demand in the face of the decreased reserve can lead to redevelopment of cardiomyopathy [107,108]. As such, close ongoing monitoring with clinic visits, ambulatory (Holter) monitoring, and echocardiography are essential. Although there are minimal data and no society guidelines regarding the frequency of monitoring in these patients, we follow up with patients using a combination of clinic visits, echocardiography, and ambulatory monitoring every three to six months for one to two years following the initial clinical improvement. The following is a typical follow-up schedule: Four to six weeks after initial presentation Clinical follow-up, ECG. Three months after initial presentation Clinical follow-up, ECG, echocardiogram, outpatient ambulatory monitor. Six months after initial presentation Clinical follow-up, ECG. Twelve months after initial presentation Clinical follow-up, ECG, echocardiogram, ECG, outpatient ambulatory monitor if symptoms suggest recurrence. Eighteen to 24 months after initial presentation Clinical follow-up, ECG. If complete recovery of EF is noted and angiotensin converting enzyme (ACE) inhibitors and beta blockers are tapered off, additional monitoring is required to be sure that EF remains normal [4]. PROGNOSIS https://www.uptodate.com/contents/arrhythmia-induced-cardiomyopathy/print 14/29 7/6/23, 11:10 AM Arrhythmia-induced cardiomyopathy - UpToDate Following the restoration of sinus rhythm or ventricular rate control of the presenting tachycardia, most patients will have significant improvement and/or normalization of LVEF over a period of months. As such, patients who have not experienced sudden cardiac arrest or a sustained ventricular arrhythmia, and whose LVEF has improved to 40 percent or greater, usually do not require implantation of an implantable cardioverter-defibrillator (ICD). (See "Primary prevention of sudden cardiac death in patients with cardiomyopathy and heart failure with reduced LVEF".) In some patients whose LVEF has normalized, the LV chamber may remain somewhat enlarged. Despite the apparent normalization of cardiac function when a tachycardia has been terminated or rate controlled, ultrastructural abnormalities of the myocardium may persist [60]. Additional