Determinants of implantable defibrillator discharges in high-risk patients with hypertrophic cardiomyopathy

Abstract

Objectives: To identify the determinants of appropriate and inappropriate implantable cardioverterdefibrillator (ICD) discharges in patients with hypertrophic cardiomyopathy (HCM). Design: Retrospective cohort study. Setting: ICD clinic at an academic hospital. Patients: 61 patients with HCM who received ICDs for the primary or secondary prevention of sudden cardiac death (SCD). Outcome measures: (a) Analysis of appropriate and inappropriate ICD discharges; (b) predictors of ICD discharges. Results: Mean (SD) age at ICD insertion was 46 (18) years (range 10-79). Follow-up time was 40 (27) months (range 7-151). Eight patients experienced an appropriate discharge, occurring 24.5 (13.6) months after ICD insertion. Appropriate ICD intervention was more common in the secondary (36%) than the primary (8%) prevention group (p = 0.02). Inappropriate ICD discharges occurred in 20 (33%) patients. Multivariate Cox regression analysis identified two significant predictors of inappropriate ICD discharges: (a) age ,30 years at the time of ICD insertion (hazard ratio (HR) = 3.0 (95% CI 1.1 to 8.0; p = 0.03) and (b) history of atrial fibrillation (HR = 3.1 (95% CI 1.2 to 8.1; p = 0.02). Conclusions: ICDs are effective in the prevention of SCD in HCM. However, there is a high incidence of inappropriate ICD discharges.

Risk Stratification and Role of Implantable Defibrillators for Prevention of Sudden Death in Patients With Hypertrophic Cardiomyopathy

“…Consistent with the predilection of SCD in young patients with HCM, almost 30% of those receiving ICDs were ≤20 years of age, largely for primary prevention, and they experienced appropriate ICD interventions at an average of 18±4 years of age (ie, 7%/year). Intervention rates in the multicenter study are consistent with those reported individually from other countries, including Spain, 16 Poland, 17,58 Canada, 12 Portugal, 60 United Kingdom, 61 Germany, 59 Australia, 11 Italy 9 and other U.S. centers. 48,62, 63 It is notable that the ICD has performed so reliably in terminating VT/VF in patients with a disease such as HCM, which is associated with unique pathology and hemodynamic features such as a substantial increase in LV mass (wall thickening up to 3-to 5-fold greater than normal), 23,64 dynamic obstruction to LV outflow with elevated intraventricular pressures, 31,34 diastolic dysfunction and microvascular myocardial ischemia due to small vessel disease.…”

Contemporary Insights and Strategies for Risk Stratification and Prevention of Sudden Death in Hypertrophic Cardiomyopathy

“…Evidence assembled over the last 10 years substantiates that appropriate ICD interventions occur not uncommonly in HCM and are highly effective in terminating potentially lethal ventricular tachyarrhythmias 3,[7][8][9]22,35,36 (Figure 3). Indeed, ICDs have created a new strategy within the HCM armamentarium, and represent the most reliable treatment available for SD prevention.…”

Implantable cardioverter defibrillator therapy in hypertrophic cardiomyopathy: an updated systematic review and meta-analysis of outcomes and complications

“…Similarly, inappropriate shocks occurred at a rate of 4.9% (95% CI: 3.9-6.0) per year (I 2 =75%) ( Figure 3). Among six studies (7,8,10,25,29,33), heart transplant was required in 1.6% of patients per year. The annual incidence of lead malfunction and lead displacement was 1.4% (95% CI: 0.8-2.5) and 1.3% (95% CI: 0.8-2.0) respectively.…”

“…A major concern with ICD therapy is the delivery of inappropriate shocks, namely in response to supraventricular tachycardia and atrial fibrillation. Furthermore, device complications including infection, lead malfunction, and lead displacements pose additional hazards, particularly in a predominantly young patient cohort who require ICD therapy for life (4,5,7,9,10).…”