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OPINION STATEMENT: For almost the past decade, recommendations for the use of implantable cardioverter defibrillators (ICDs) for primary prevention of sudden cardiac death have been based upon the left ventricular ejection fraction (LVEF). Current guidelines recommend an ICD for heart failure patients with LVEF ≤35% and NYHA functional class of II or III; however, because the majority of heart failure patients who qualify for ICD implantation based on these criteria will never have an event requiring ICD therapy over several years of follow-up, additional methods of risk stratification for sudden death are clearly needed. Additionally, most of the nearly 300,000 cardiac arrests that occur each year occur in patients without heart failure or significant left ventricular dysfunction. To improve the identification of patients at risk for sudden death, several criteria other than ejection fraction have been proposed and studied. Markers of autonomic tone, including heart rate turbulence and QT dynamicity, have shown some ability to predict total mortality but not arrhythmic events. Microvolt T-wave alternans testing was initially thought to be highly predictive of life-threatening arrhythmias, but prospective large sub-studies of the MADIT II and SCD-HeFT trials have failed to show a predictive value for T-wave alternans testing. Newer markers for risk are based upon the detection of myocardial fibrosis, which forms the substrate for re-entrant and malignant ventricular tachyarrhythmias. Markers of collagen turnover or quantification of myocardial scar by MRI may hold the best promise for identifying patients at highest risk for sudden cardiac death and may also identify patients at high risk but with an ejection fraction above 35%, who are not currently recommended for ICD implantation.
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BACKGROUND: Limited data exist regarding the outcome of atrial fibrillation (AF) surgery and catheter ablation in patients with hypertrophic cardiomyopathy (HCM). OBJECTIVE: The purpose of this study was to evaluate the safety and efficacy of nonpharmacologic treatment of AF in HCM. METHODS: One hundred forty-seven patients (46 female, age 55 ± 11 years, ejection fraction [EF] 58% ± 8%) with symptomatic paroxysmal (58%), persistent (31%), and long-standing persistent AF (11%) refractory to antiarrhythmic drugs who presented for their first catheter ablation (n = 79) or AF surgery (n = 68) were included. RESULTS: After follow-up of 35 months (interquartile range 13, 60), 29% of patients who underwent catheter ablation and 51% of those who had undergone AF surgery had no documented recurrent atrial arrhythmia after a single procedure. Repeat ablation was performed in 55% of patients with recurrent arrhythmia in the catheter group and 24% in the surgery group, increasing the success rate to 39% and 53%, respectively, after 1 or more procedures. Predictors of success after the first procedure in a multivariable setting included higher baseline EF and male gender. Persistent or long-standing AF and log of AF duration were associated with lower success. Major complications occurred in 6% of the catheter ablation group and 18% of the AF surgery group. During follow-up, 16 patients died (9 in catheter group, 7 in surgery group) and 1 underwent heart replacement. Lower baseline EF and older age were independently associated with death. CONCLUSION: Catheter ablation and AF surgery are associated with symptomatic improvement in HCM patients. However, long-term success is lower and complications are higher than previously reported.