Abstract 16813: The Prevalence and Predictors of Pacing-Induced Cardiomyopathy (PICM) in Younger Patients

Abstract

Background: Pacing-induced cardiomyopathy (PICM) has been increasingly recognized as a cause of heart failure in patients with pacemakers. Thus far, clinical trials and observational studies of PICM have largely included elderly patients with mean age > 70 years. The prevalence and predictors of PICM in younger patients (age ≤ 59 years) after pacemaker implantation are not known. Methods: We retrospectively studied the prevalence and predictors of PICM in younger adults (18-59 years) who received single ventricular chamber or dual chamber pacemakers at Vanderbilt University Medical Center from 1986-2015. Patients without documented ventricular pacing burden, and patients with baseline left ventricular ejection fraction (LVEF) < 30% were excluded. PICM was defined as LVEF drop of ≥ 10% and LVEF < 50% during follow up in the setting of significant right ventricular pacing (≥ 20%), without alternative explanations for cardiomyopathy. Univariate and multivariable Cox proportional hazards regression models were utilized to study the factors associated with hazard of developing PICM. Results: A total of 325 patients were included in the study. 182 patients had high ventricular pacing (≥ 20%), which was associated with pre-existing atrial fibrillation (AF) and reduced baseline LVEF in addition to atrioventricular block (AVB) in the multivariate analysis. During the median follow up duration of 11.5 (Interquartile range 7 - 17) years, 38 patients (11.7%) developed PICM (1.3 per 100 patient-year). The median time to the development of PICM was 5 (Interquartile range 2 - 10) years. Older age (HR 2.5 for age ≥ 50 years, P = 0.013), reduced baseline LVEF (HR 2.4, P = 0.022), and AVB (HR 2.7, P = 0.007) were associated with an increased risk of PICM in the multivariate analysis. Furthermore, pre-existing AF was associated with an increased risk of PICM in patients without pre-implant AVB (HR 8.8 compared to the absence of both AF and AVB, P = 0.039). Conclusion: The incidence of PICM in young patients was low in this cohort of younger patients. Older age, baseline reduced LVEF, and AVB were associated with an increased risk of PICM in the young patient cohort. AF was associated with an increased risk of PICM in a subset of patients without pre-existing AVB at implant.