Hypertrophic cardiomyopathy. Long term outcomes of patients with implantable cardioverter defibrillator in a single centre

Abstract

Background: Sudden cardiac death (SCD) is a common mode of death in Hypertrophic cardiomyopathy (HCM). Implantable cardioverter defibrillator (ICD) is the most effective therapy for prevention of SCD but it is not excempt of complications. Purpose: To assess the incidence of SCD, ICD therapies and device-related complications in patients (pts) with HCM who received an ICD for primary or secondary prevention of SCD during a long term follow-up. Methods: A retrospective, observational cohort study analysis was performed. Between 1995 and 2012, from 636 pts with HCM, 88 pts who received an ICD were followed. Indications for secondary prevention were sustained ventricular tachycardia (VT) or cardiac arrest in 14 pts (15.9%) and the traditional 5 risk factors (RF) of the 2003 ACC/ESC risk stratification algorithm for primary prevention of SCD (non-sustained VT, severe left ventricular hypertrophy, family history of SCD, unexplained syncope and abnormal blood pressure response to exercise) in 74 pts (84.1%). A combined endpoint of SCD or appropriate ICD therapy (AT), incidence of inappropriate ICD therapy (IT) and device-related complications were assessed. Variables were analyzed with chi2 test and survival curves with Kaplan-Meier method. Median follow-up was 54.5 months. Results: Mean age was 38.4±18 years, (59% male). 1. ICD implanted for secondary prevention: a) the incidence of SCD/AT was 35.7% (5/14 pts); b) the rate of IT was 14.2% (2/14 pts) both due to atrial fibrillation; c) there was no ICD related-complications. 2. ICD implanted for primary prevention: a) the incidence of SCD/AT was 8.1% (6/74): 1 pt with 1 RF, 2 pts with 2 RF and 3 pts with 3 RF for SCD; b) the rate of IT was 20.2% (15/74 pts), 5 atrial fibrillation, 3 noise oversensing, 6 sinus tachycardia and 1 atrial tachycardia; c) 13 pts (14.7%) had ICD related-complications: infection 5 pts, lead displacement 4 pts, pericardial effusion 2 pts and lead fracture 2 pts. The incidence of SCD/AT was 8.1% vs 35.7% in primary vs secondary prevention (p: 0.004). Survival free of SCD/AT in pts implanted for primary prevention at 72 months was 86.1%. Conclusions: In this study population ICDs were highly effective in the setting of secondary prevention. Pts with ICD for primary prevention had a significantly lower incidence of SCD/AT and a high rate of IT and ICD-related complications. These findings suggests that the current risk algorithm for primary prevention needs to be improved to distinguish high from low risk pts.