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

Abstract

To identify the determinants of appropriate and inappropriate implantable cardioverter-defibrillator (ICD) discharges in patients with hypertrophic cardiomyopathy (HCM). Retrospective cohort study. ICD clinic at an academic hospital. 61 patients with HCM who received ICDs for the primary or secondary prevention of sudden cardiac death (SCD). (a) Analysis of appropriate and inappropriate ICD discharges; (b) predictors of ICD discharges. 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). ICDs are effective in the prevention of SCD in HCM. However, there is a high incidence of inappropriate ICD discharges.