Prevalence and predictors of pacing-induced cardiomyopathy in young adult patients (< 60 years) with pacemakers.

INTRODUCTION Clinical trials and observational studies of pacing-induced cardiomyopathy (PICM) have largely included elderly patients with mean age > 70 years. The prevalence and predictors of PICM in younger patients (age < 60 years) after pacemaker implantation are not known. METHODS Adults (18-59 years) who received single chamber ventricular or dual chamber pacemakers at Vanderbilt University Medical Center from 1986-2015 were included. Patients without documented ventricular pacing burden, and patients with baseline left ventricular ejection fraction (LVEF) < 35% were excluded. PICM was defined as LVEF decrease of ≥ 10% and LVEF < 50% during follow up with right ventricular pacing ≥ 20%, and without alternative explanations for cardiomyopathy. RESULTS A total of 325 patients were included in the study. During a median follow up duration of 11.5 (Interquartile range 7 - 17) years, 38 patients (11.7%) developed PICM (1.3 per 100 patient-year). Older age (HR 2.5 for age ≥ 50 years, P = 0.013), reduced baseline LVEF (HR 2.4, P = 0.022), and pre-implant AVB (HR 2.7, P = 0.007) were associated with an increased risk of PICM in the multivariate analysis. Furthermore, baseline AF conferred an increased risk of PICM only in patients without pre-implant AVB but not patients with pre-implant AVB. CONCLUSIONS The incidence of PICM in young patients was low, but PICM could occur more than a decade after pacemaker implantation. Older age, baseline reduced LVEF, and pre-implant AVB were associated with an increased risk of PICM in the young patient cohort. This article is protected by copyright. All rights reserved.