ablation in patients without an apical aneurysm is uncertain. (See "Secondary prevention of sudden cardiac death in heart failure and cardiomyopathy", section on 'Other treatment options'.) ACKNOWLEDGMENT The editorial staff at UpToDate would like to acknowledge Perry Elliott, MD, who contributed to an earlier version of this topic review. Use of UpToDate is subject to the Terms of Use. REFERENCES 1. Elliott PM, Sharma S, Varnava A, et al. Survival after cardiac arrest or sustained ventricular tachycardia in patients with hypertrophic cardiomyopathy. J Am Coll Cardiol 1999; 33:1596. 2. Maron BJ, Spirito P, Shen WK, et al. Implantable cardioverter-defibrillators and prevention of sudden cardiac death in hypertrophic cardiomyopathy. JAMA 2007; 298:405. 3. Begley DA, Mohiddin SA, Tripodi D, et al. Efficacy of implantable cardioverter defibrillator therapy for primary and secondary prevention of sudden cardiac death in hypertrophic cardiomyopathy. Pacing Clin Electrophysiol 2003; 26:1887. 4. Spirito P, Autore C. Management of hypertrophic cardiomyopathy. BMJ 2006; 332:1251. 5. Gersh BJ, Maron BJ, Bonow RO, et al. 2011 ACCF/AHA guideline for the diagnosis and treatment of hypertrophic cardiomyopathy: a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines. Circulation 2011; 124:e783. 6. Authors/Task Force members, Elliott PM, Anastasakis A, et al. 2014 ESC Guidelines on diagnosis and management of hypertrophic cardiomyopathy: the Task Force for the Diagnosis and Management of Hypertrophic Cardiomyopathy of the European Society of Cardiology (ESC). Eur Heart J 2014; 35:2733. 7. Maron BJ, Shen WK, Link MS, et al. Efficacy of implantable cardioverter-defibrillators for the prevention of sudden death in patients with hypertrophic cardiomyopathy. N Engl J Med 2000; 342:365. 8. Cecchi F, Maron BJ, Epstein SE. Long-term outcome of patients with hypertrophic cardiomyopathy successfully resuscitated after cardiac arrest. J Am Coll Cardiol 1989; 13:1283. https://www.uptodate.com/contents/hypertrophic-cardiomyopathy-management-of-ventricular-arrhythmias-and-sudden-cardiac-death-risk/print 12/24 7/6/23, 3:27 PM Hypertrophic cardiomyopathy: Management of ventricular arrhythmias and sudden cardiac death risk - UpToDate 9. Primo J, Geelen P, Brugada J, et al. Hypertrophic cardiomyopathy: role of the implantable cardioverter-defibrillator. J Am Coll Cardiol 1998; 31:1081. 10. Magnusson P, Gadler F, Liv P, M rner S. Risk Markers and Appropriate Implantable Defibrillator Therapy in Hypertrophic Cardiomyopathy. Pacing Clin Electrophysiol 2016; 39:291. 11. Thavikulwat AC, Tomson TT, Knight BP, et al. Appropriate Implantable Defibrillator Therapy in Adults With Hypertrophic Cardiomyopathy. J Cardiovasc Electrophysiol 2016; 27:953. 12. Al-Khatib SM, Stevenson WG, Ackerman MJ, et al. 2017 AHA/ACC/HRS Guideline for Management of Patients With Ventricular Arrhythmias and the Prevention of Sudden Cardiac Death: 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 2018; 72:e91. 13. Wang W, Lian Z, Rowin EJ, et al. Prognostic Implications of Nonsustained Ventricular Tachycardia in High-Risk Patients With Hypertrophic Cardiomyopathy. Circ Arrhythm Electrophysiol 2017; 10. 14. Maron BJ, Spirito P, Ackerman MJ, et al. Prevention of sudden cardiac death with implantable cardioverter-defibrillators in children and adolescents with hypertrophic cardiomyopathy. J Am Coll Cardiol 2013; 61:1527. 15. Weinstock J, Bader YH, Maron MS, et al. Subcutaneous Implantable Cardioverter Defibrillator in Patients With Hypertrophic Cardiomyopathy: An Initial Experience. J Am Heart Assoc 2016; 5. 16. Maurizi N, Olivotto I, Olde Nordkamp LR, et al. Prevalence of subcutaneous implantable cardioverter-defibrillator candidacy based on template ECG screening in patients with hypertrophic cardiomyopathy. Heart Rhythm 2016; 13:457. 17. Lambiase PD, Gold MR, Hood M, et al. Evaluation of subcutaneous ICD early performance in hypertrophic cardiomyopathy from the pooled EFFORTLESS and IDE cohorts. Heart Rhythm 2016; 13:1066. 18. Nazer B, Dale Z, Carrassa G, et al. Appropriate and inappropriate shocks in hypertrophic cardiomyopathy patients with subcutaneous implantable cardioverter-defibrillators: An international multicenter study. Heart Rhythm 2020; 17:1107. 19. Maron MS, Steiger N, Burrows A, et al. Evidence That Subcutaneous Implantable Cardioverter-Defibrillators Are Effective and Reliable in Hypertrophic Cardiomyopathy. JACC Clin Electrophysiol 2020; 6:1019. 20. Schinkel AF, Vriesendorp PA, Sijbrands EJ, et al. Outcome and complications after implantable cardioverter defibrillator therapy in hypertrophic cardiomyopathy: systematic https://www.uptodate.com/contents/hypertrophic-cardiomyopathy-management-of-ventricular-arrhythmias-and-sudden-cardiac-death-risk/print 13/24 7/6/23, 3:27 PM Hypertrophic cardiomyopathy: Management of ventricular arrhythmias and sudden cardiac death risk - UpToDate review and meta-analysis. Circ Heart Fail 2012; 5:552. 21. Vriesendorp PA, Schinkel AF, Van Cleemput J, et al. Implantable cardioverter-defibrillators in hypertrophic cardiomyopathy: patient outcomes, rate of appropriate and inappropriate interventions, and complications. Am Heart J 2013; 166:496. 22. Berul CI, Van Hare GF, Kertesz NJ, et al. Results of a multicenter retrospective implantable cardioverter-defibrillator registry of pediatric and congenital heart disease patients. J Am Coll Cardiol 2008; 51:1685. 23. Maron BJ, Casey SA, Olivotto I, et al. Clinical Course and Quality of Life in High-Risk Patients With Hypertrophic Cardiomyopathy and Implantable Cardioverter-Defibrillators. Circ Arrhythm Electrophysiol 2018; 11:e005820. 24. Maron BJ, Maron MS. Contemporary strategies for risk stratification and prevention of sudden death with the implantable defibrillator in hypertrophic cardiomyopathy. Heart Rhythm 2016; 13:1155. 25. McKenna WJ, Oakley CM, Krikler DM, Goodwin JF. Improved survival with amiodarone in patients with hypertrophic cardiomyopathy and ventricular tachycardia. Br Heart J 1985; 53:412. 26. McKenna WJ, Harris L, Rowland E, et al. Amiodarone for long-term management of patients with hypertrophic cardiomyopathy. Am J Cardiol 1984; 54:802. 27. Mantica M, Della Bella P, Arena V. Hypertrophic cardiomyopathy with apical aneurysm: a case of catheter and surgical therapy of sustained monomorphic ventricular tachycardia. Heart 1997; 77:481. 28. Rodriguez LM, Smeets JL, Timmermans C, et al. Radiofrequency catheter ablation of sustained monomorphic ventricular tachycardia in hypertrophic cardiomyopathy. J Cardiovasc Electrophysiol 1997; 8:803. 29. Rowin EJ, Maron BJ, Haas TS, et al. Hypertrophic Cardiomyopathy With Left Ventricular Apical Aneurysm: Implications for Risk Stratification and Management. J Am Coll Cardiol 2017; 69:761. 30. Saberi S, Wheeler M, Bragg-Gresham J, et al. Effect of Moderate-Intensity Exercise Training on Peak Oxygen Consumption in Patients With Hypertrophic Cardiomyopathy: A Randomized Clinical Trial. JAMA 2017; 317:1349. 31. Klempfner R, Kamerman T, Schwammenthal E, et al. Efficacy of exercise training in symptomatic patients with hypertrophic cardiomyopathy: results of a structured exercise training program in a cardiac rehabilitation center. Eur J Prev Cardiol 2015; 22:13. 32. Sheikh N, Papadakis M, Schnell F, et al. Clinical Profile of Athletes With Hypertrophic https://www.uptodate.com/contents/hypertrophic-cardiomyopathy-management-of-ventricular-arrhythmias-and-sudden-cardiac-death-risk/print 14/24 7/6/23, 3:27 PM Hypertrophic cardiomyopathy: Management of ventricular arrhythmias and sudden cardiac death risk - UpToDate Cardiomyopathy. Circ Cardiovasc Imaging 2015; 8:e003454. 33. Dejgaard LA, Haland TF, Lie OH, et al. Vigorous exercise in patients with hypertrophic cardiomyopathy. Int J Cardiol 2018; 250:157. 34. Pelliccia A, Solberg EE, Papadakis M, et al. Recommendations for participation in competitive and leisure time sport in athletes with cardiomyopathies, myocarditis, and pericarditis: position statement of the Sport Cardiology Section of the European Association of Preventive Cardiology (EAPC). Eur Heart J 2019; 40:19. Topic 119625 Version 9.0 https://www.uptodate.com/contents/hypertrophic-cardiomyopathy-management-of-ventricular-arrhythmias-and-sudden-cardiac-death-risk/print 15/24 7/6/23, 3:27 PM Hypertrophic cardiomyopathy: Management of ventricular arrhythmias and sudden cardiac death risk - UpToDate GRAPHICS Morphologic variants of hypertrophic cardiomyopathy HCM typically presents with asymmetric or localized areas of LV hypertrophy, which are diagrammed in B to J. (A) Normal LV wall thickness. (B) ASH. (C) Sigmoid septum, which is more common in older adults. (D) Midcavity hypertrophy associated with midcavity obstruction. (E) Predominantly free wall hypertrophy, an unusual pattern in HCM. (F) LV wall thinning (associated with low LV ejection fraction) and biatrial enlargement. (G) Predominantly apical LV hypertrophy. (H) Severe concentric hypertrophy with cavity obliteration. (I) Biventricular hypertrophy. (J) Mild to moderate symmetric hypertrophy. https://www.uptodate.com/contents/hypertrophic-cardiomyopathy-management-of-ventricular-arrhythmias-and-sudden-cardiac-death-risk/print 16/24 7/6/23, 3:27 PM Hypertrophic cardiomyopathy: Management of ventricular arrhythmias and sudden cardiac death risk - UpToDate HCM: hypertrophic cardiomyopathy; LV: left ventricular; ASH: asymmetrical septal hypertrophy. Graphic 58156 Version 6.0 https://www.uptodate.com/contents/hypertrophic-cardiomyopathy-management-of-ventricular-arrhythmias-and-sudden-cardiac-death-risk/print 17/24 7/6/23, 3:27 PM Hypertrophic cardiomyopathy: Management of ventricular arrhythmias and sudden cardiac death risk - UpToDate Established major risk markers and risk modifiers associated with increased risk of sudden cardiac death (SCD) in hypertrophic cardiomyopathy (HCM) Risk factor Comment Major risk factors Family history of HCM- related SCD SCD due to HCM in a close relative, particularly if <40 years of age, should be considered evidence for increased risk of SCD in other related family members. Syncope Unexplained syncope that, based on clinical history, appears to be due to arrhythmia (and not neurally mediated) is associated with increased SCD risk, particularly in young patients and when the event occurred close to the time of evaluation (<6 months). Massive LV hypertrophy An increased risk of SCD in patients with HCM is seen in patients with echocardiographic evidence of 30 mm wall thickness anywhere in the LV chamber. If maximal wall thickness is not clearly defined using echocardiography, additional evaluation with CMR to clarify the extent of LV wall thickening may be warranted. LV apical aneurysm Uncommon subgroup with thin-walled dyskinetic LV apex with regional scarring. LV apical aneurysm is associated with increased risk for sustained monomorphic VT and warrants consideration for ICD. End-stage HCM (LVEF <50 percent) Higher incidence of life-threatening VT associated with this uncommon phase of HCM. These patients often develop advanced heart failure at a young age and therefore are often considered for ICD as a bridge to definitive therapy with heart transplant. Risk Modifiers Extensive LGE (ie, myocardial fibrosis) occupying 15 percent of LV mass is associated with markers of disease severity and adverse Extensive LGE by contrast-enhanced CMR outcomes including increased risk for SCD and should be considered an important arbitrator to resolving ICD decision-making when uncertain following assessment with established major risk markers. Age at time of SCD risk assessment Risk of SCD is greatest in young patients <30 years old and lessens through mid-life. In patients who have achieved advanced age ( 60 years), risk of SCD is low, even in the presence of other risk factors. Defined as 3 consecutive ventricular beats at >120 beats per minute, lasting less than 30 seconds. Multiple bursts identified on ambulatory monitoring are associated with increased risk, particularly in younger patients. Although the data relating characteristics of NSVT to SCD risk NSVT on ambulatory monitoring remain poorly defined, it would be reasonable to give greater weight to increased SCD risk in those patients with HCM with NSVT that is https://www.uptodate.com/contents/hypertrophic-cardiomyopathy-management-of-ventricular-arrhythmias-and-sudden-cardiac-death-risk/print 18/24 7/6/23, 3:27 PM Hypertrophic cardiomyopathy: Management of ventricular arrhythmias and sudden cardiac death risk - UpToDate frequent (>1 burst), of long duration (>7 beats), or particularly fast (>200 beats per minute). LVEF: left ventricular ejection fraction; CMR: cardiovascular magnetic resonance; NSVT: nonsustained ventricular tachycardia; BP: blood pressure; ICD: implantable cardioverter-defibrillator; LGE: late gadolinium enhancement; LVOT: left ventricular outflow tract obstruction. Graphic 102357 Version 9.0 https://www.uptodate.com/contents/hypertrophic-cardiomyopathy-management-of-ventricular-arrhythmias-and-sudden-cardiac-death-risk/print 19/24 7/6/23, 3:27 PM Hypertrophic cardiomyopathy: Management of ventricular arrhythmias and sudden cardiac death risk - UpToDate Algorithm showing the indications for implantable cardioverter-defibrillator (ICD) placement in patients with hypertrophic cardiomyopathy (HCM) Regardless of the level of recommendation put forth in these guidelines, the decision for placement of an ICD must involve prudent application of individual clinical judgment, thorough discussions of the strength of evidence, the benefits, and the risks (including but not limited to inappropriate discharges, lead and procedural complications) to allow active participation of the fully informed patient in ultimate decision making. ICD: implantable cardioverter-defibrillator; HCM: hypertrophic cardiomyopathy; VT: ventricular tachycardia; SD: sudden death; LV: left ventricular; BP: blood pressure; SCD: sudden cardiac death. SCD risk modifiers include established risk factors and emerging risk modifiers. Reproduced from: Gersh BJ, Maron BJ, Bonow RO, et al. 2011 ACCF/AHA guideline for the diagnosis and treatment of hypertrophic cardiomyopathy: A report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines. Developed in collaboration with the American Association for Thoracic Surgery, American Society of Echocardiography, American Society of Nuclear Cardiology, Heart Failure Society of America, Heart Rhythm Society, Society for Cardiovascular Angiography and Interventions, and Society of Thoracic Surgeons. J Am https://www.uptodate.com/contents/hypertrophic-cardiomyopathy-management-of-ventricular-arrhythmias-and-sudden-cardiac-death-risk/print 20/24 7/6/23, 3:27 PM Hypertrophic cardiomyopathy: Management of ventricular arrhythmias and sudden cardiac death risk - UpToDate Coll Cardiol 2011; 58:e212. Illustration used with the permission of Elsevier Inc. All rights reserved. Graphic 102271 Version 3.0 https://www.uptodate.com/contents/hypertrophic-cardiomyopathy-management-of-ventricular-arrhythmias-and-sudden-cardiac-death-risk/print 21/24 7/6/23, 3:27 PM Hypertrophic cardiomyopathy: Management of ventricular arrhythmias and sudden cardiac death risk - UpToDate Classification of sports based on peak static and dynamic components during competition This classification is based on peak static and dynamic components achieved during competition; however, higher values may be reached during training. The increasing dynamic component is defined in terms of the estimated percentage of maximal oxygen uptake (VO max) achieved and results in an increasing cardiac output. The increasing static component is related to the estimated percentage of maximal voluntary contraction reached and results in an increasing blood pressure load. The lowest total cardiovascular demands (cardiac output and blood pressure) are shown 2 in the palest color, with increasing dynamic load depicted by increasing blue intensity and increasing static load by increasing red intensity. Note the graded transition between categories, which should be individualized on the basis of player position and style of play. Danger of bodily collision (refer to UpToDate content regarding sports according to risk of impact and educational background). https://www.uptodate.com/contents/hypertrophic-cardiomyopathy-management-of-ventricular-arrhythmias-and-sudden-cardiac-death-risk/print 22/24 7/6/23, 3:27 PM Hypertrophic cardiomyopathy: Management of ventricular arrhythmias and sudden cardiac death risk - UpToDate Increased risk if syncope occurs. Reproduced from: Levine BD, Baggish AL, Kovacs RJ. Eligibility and disquali cation recommendations for competitive athletes with cardiovascular abnormalities: Task force 1: Classi cation of sports: Dynamic, static, and impact: A scienti c statement from the American Heart Association and American College of Cardiology. J Am Coll Cardiol 2015; 66:2350. Illustration used with the permission of Elsevier Inc. All rights reserved. Graphic 105651 Version 9.0 https://www.uptodate.com/contents/hypertrophic-cardiomyopathy-management-of-ventricular-arrhythmias-and-sudden-cardiac-death-risk/print 23/24 7/6/23, 3:27 PM Hypertrophic cardiomyopathy: Management of ventricular arrhythmias and sudden cardiac death risk - UpToDate Contributor Disclosures Martin S Maron, MD Grant/Research/Clinical Trial Support: iRhythm [Hypertrophic cardiomyopathy]. Consultant/Advisory Boards: Cytokinetics [Steering committee, REDWOOD-HCM]; Edgewise Pharmaceuticals [Myosin inhibitor for treatment of symptomatic hypertrophic cardiomyopathy]; Imbria Pharmaceuticals [Hypertrophic cardiomyopathy]. All of the relevant financial relationships listed have been mitigated. Samuel L vy, MD No relevant financial relationship(s) with ineligible companies to disclose. William J McKenna, MD Consultant/Advisory Boards: Bristol Meyers Squibb [Novel pharmacological treatments for HCM]; Cytokinetics [Novel pharmacological treatments for HCM]; Health in Code [Genetic testing in inherited cardiac disease]; Tenaya Therapeutics [Gene therapy in cardiomyopathy]. All of the relevant financial relationships listed have been mitigated. Todd F Dardas, MD, MS 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/hypertrophic-cardiomyopathy-management-of-ventricular-arrhythmias-and-sudden-cardiac-death-risk/print 24/24