Ventricular tachycardia/fibrillation early after defibrillator implantation in patients with hypertrophic cardiomyopathy is explained by a high risk subgroup of patients.

BACKGROUND: Implantable cardioverter-defibrillator (ICD) studies in patients with coronary artery disease report higher risk of ventricular tachycardia/fibrillation (VT/VF) early post-implant, potentially related to local proarrhythmic effects of ICD leads. OBJECTIVE: To characterize early and long-term risk of ICD discharge for VT/VF in a large hypertrophic cardiomyopathy (HCM) cohort. METHODS: By using HCM multicenter registry data, we compared long-term risk of VT/VF subsequent to an early post-implant period (a priori defined as within 3 months of implant) between patients with or without VT/VF within 3 months after ICD implantation. RESULTS: Over a median follow-up of 4.3 years, 109 of 506 (22%) patients with HCM who received ICDs received at least 1 ICD discharge for VT/VF. Risk of first ICD discharge for VT/VF was highest in the first year post-implant (10.8% per person-year; 95% confidence interval 7.9-13.8) and particularly in the first 3 months (17.0% per person-year; 95% confidence interval 9.8-24.3). Patients with early VT/VF (≤3 months post-implant) were older, and more commonly had secondary prevention ICDs following cardiac arrest or systolic dysfunction (end-stage HCM with ejection fraction<50%). Only 2 of 247 (0.7%) patients with primary prevention ICDs and preserved systolic function had early VT/VF. Patients with VT/VF early post-implant (≤3 months) had more than 5-fold higher risk for future VT/VF during long-term follow-up compared with patients without early VT/VF (adjusted hazard ratio 5.4; 95% confidence interval 2.3-12.6). CONCLUSIONS: High-risk patients with HCM and VT/VF early after ICD implantation are particularly prone to subsequent VT/VF throughout follow-up. Early ICD interventions for VT/VF are largely confined to patients with prior cardiac arrest or systolic dysfunction and therefore more likely driven by higher arrhythmic risk rather than lead-related proarrhythmia

Implantable cardioverter-defibrillators and prevention of sudden cardiac death inhypertrophic cardiomyopathy.

CONTEXT: Recently, the implantable cardioverter-defibrillator (ICD) has been promoted for prevention of sudden death in hypertrophic cardiomyopathy (HCM). However, the effectiveness and appropriate selection of patients for this therapy is incompletely resolved. OBJECTIVE: To study the relationship between clinical risk profile and incidence and efficacy of ICD intervention in HCM. DESIGN, SETTING, AND PATIENTS: Multicenter registry study of ICDs implanted between 1986 and 2003 in 506 unrelated patients with HCM. Patients were judged to be at high risk for sudden death; had received ICDs; underwent evaluation at 42 referral and nonreferral institutions in the United States, Europe, and Australia; and had a mean follow-up of 3.7 (SD, 2.8) years. Measured risk factors for sudden death included family history of sudden death, massive left ventricular hypertrophy, nonsustained ventricular tachycardia on Holter monitoring, and unexplained prior syncope. MAIN OUTCOME MEASURE: Appropriate ICD intervention terminating ventricular tachycardia or fibrillation. RESULTS: The 506 patients were predominately young (mean age, 42 [SD, 17] years) at implantation, and most (439 [87%]) had no or only mildly limiting symptoms. ICD interventions appropriately terminated ventricular tachycardia/fibrillation in 103 patients (20%). Intervention rates were 10.6% per year for secondary prevention after cardiac arrest (5-year cumulative probability, 39% [SD, 5%]), and 3.6% per year for primary prevention (5-year probability, 17% [SD, 2%]). Time to first appropriate discharge was up to 10 years, with a 27% (SD, 7%) probability 5 years or more after implantation. For primary prevention, 18 of the 51 patients with appropriate ICD interventions (35%) had undergone implantation for only a single risk factor; likelihood of appropriate discharge was similar in patients with 1, 2, or 3 or more risk markers (3.83, 2.65, and 4.82 per 100 person-years, respectively; P = .77). The single sudden death due to an arrhythmia (in the absence of advanced heart failure) resulted from ICD malfunction. ICD complications included inappropriate shocks in 136 patients (27%). CONCLUSIONS: In a high-risk HCM cohort, ICD interventions for life-threatening ventricular tachyarrhythmias were frequent and highly effective in restoring normal rhythm. An important proportion of ICD discharges occurred in primary prevention patients who had undergone implantation for a single risk factor. Therefore, a single marker of high risk for sudden death may be sufficient to justify consideration for prophylactic defibrillator implantation in selected patients with HCM

Implantable cardioverter-defibrillators and prevention of sudden cardiac death in hypertrophic cardiomyopathy

CONTEXT: Recently, the implantable cardioverter-defibrillator (ICD) has been promoted for prevention of sudden death in hypertrophic cardiomyopathy (HCM). However, the effectiveness and appropriate selection of patients for this therapy is incompletely resolved. OBJECTIVE: To study the relationship between clinical risk profile and incidence and efficacy of ICD intervention in HCM. DESIGN, SETTING, AND PATIENTS: Multicenter registry study of ICDs implanted between 1986 and 2003 in 506 unrelated patients with HCM. Patients were judged to be at high risk for sudden death; had received ICDs; underwent evaluation at 42 referral and nonreferral institutions in the United States, Europe, and Australia; and had a mean follow-up of 3.7 (SD, 2.8) years. Measured risk factors for sudden death included family history of sudden death, massive left ventricular hypertrophy, nonsustained ventricular tachycardia on Holter monitoring, and unexplained prior syncope. MAIN OUTCOME MEASURE: Appropriate ICD intervention terminating ventricular tachycardia or fibrillation. RESULTS: The 506 patients were predominately young (mean age, 42 [SD, 17] years) at implantation, and most (439 [87%]) had no or only mildly limiting symptoms. ICD interventions appropriately terminated ventricular tachycardia/fibrillation in 103 patients (20%). Intervention rates were 10.6% per year for secondary prevention after cardiac arrest (5-year cumulative probability, 39% [SD, 5%]), and 3.6% per year for primary prevention (5-year probability, 17% [SD, 2%]). Time to first appropriate discharge was up to 10 years, with a 27% (SD, 7%) probability 5 years or more after implantation. For primary prevention, 18 of the 51 patients with appropriate ICD interventions (35%) had undergone implantation for only a single risk factor; likelihood of appropriate discharge was similar in patients with 1, 2, or 3 or more risk markers (3.83, 2.65, and 4.82 per 100 person-years, respectively; P = .77). The single sudden death due to an arrhythmia (in the absence of advanced heart failure) resulted from ICD malfunction. ICD complications included inappropriate shocks in 136 patients (27%). CONCLUSIONS: In a high-risk HCM cohort, ICD interventions for life-threatening ventricular tachyarrhythmias were frequent and highly effective in restoring normal rhythm. An important proportion of ICD discharges occurred in primary prevention patients who had undergone implantation for a single risk factor. Therefore, a single marker of high risk for sudden death may be sufficient to justify consideration for prophylactic defibrillator implantation in selected patients with HCM

Implantable cardioverter-defibrillators and prevention of sudden cardiac death in hypertrophic cardiomyopathy

Context Recently, the implantable cardioverter-defibrillator (ICD) has been promoted for prevention of sudden death in hypertrophic cardiomyopathy (HCM). However, the effectiveness and appropriate selection of patients for this therapy is incompletely resolved. Objective To study the relationship between clinical risk profile and incidence and efficacy of ICD intervention in HCM. Design, Setting, and Patients Multicenter registry study of ICDs implanted between 1986 and 2003 in 506 unrelated patients with HCM. Patients were judged to be at high risk for sudden death; had received ICDs; underwent evaluation at 42 referral and nonreferral institutions in the United States, Europe, and Australia; and had a mean follow-up of 3.7 (SD, 2.8) years. Measured risk factors for sudden death included family history of sudden death, massive left ventricular hypertrophy, nonsustained ventricular tachycardia on Holter monitoring, and unexplained prior syncope. Main OutcomeMeasure Appropriate ICD intervention terminating ventricular tachycardia or fibrillation. Results The 506 patients were predominately young (mean age, 42 [SD, 17] years) at implantation, and most (439 [87%]) had no or only mildly limiting symptoms. ICD interventions appropriately terminated ventricular tachycardia/fibrillation in 103 patients (20%). Intervention rates were 10.6% per year for secondary prevention after cardiac arrest (5-year cumulative probability, 39% [SD, 5%]), and 3.6% per year for primary prevention (5-year probability, 17% [SD, 2%]). Time to first appropriate discharge was up to 10 years, with a 27% (SD, 7%) probability 5 years or more after implantation. For primary prevention, 18 of the 51 patients with appropriate ICD interventions (35%) had undergone implantation for only a single risk factor; likelihood of appropriate discharge was similar in patients with 1, 2, or 3 or more risk markers (3.83, 2.65, and 4.82 per 100 person-years, respectively; P=.77). The single sudden death due to an arrhythmia (in the absence of advanced heart failure) resulted from ICD malfunction. ICD complications included inappropriate shocks in 136 patients (27%). Conclusions In a high-risk HCM cohort, ICD interventions for life-threatening ventricular tachyarrhythmias were frequent and highly effective in restoring normal rhythm. An important proportion of ICD discharges occurred in primary prevention patients who had undergone implantation for a single risk factor. Therefore, a single marker of high risk for sudden death may be sufficient to justify consideration for prophylactic defibrillator implantation in selected patients with HCM