Ventricular pacing and myocardial function in patient with congenital heart block.

INTRODUCTION Pacing-induced cardiomyopathy (PICM) is a potential complication of chronic right ventricular (RV) pacing, but its characterization in adult patients is often complicated by pre-existing cardiomyopathy. This study investigated the incidence of PICM in patients with congenital heart block (cHB) who have conduction disease from birth without confounding pre-existing cardiac conditions. METHODS AND RESULTS This retrospective cohort analysis included 42 patients with cHB and baseline left ventricular ejection fraction (LVEF) ≥50%. Kaplan-Meier analysis was used to assess freedom from cardiomyopathy (defined as LVEF <50%) between paced and nonpaced patients. Patients were 26 ± 3 years old at first presentation, 64% were women and baseline LVEF was 60.0 ± 0.2%. Median follow-up from birth was 35 (interquartile range [IQR]: 20-42) years with a median of 6.7 years (IQR: 3.6-9.2) at our institution. Thirty-two patients received pacing at mean age 21 ± 3 years. Patients receiving a pacemaker (PM) were significantly more likely to develop a cardiomyopathy (p = .021) and no patient developed a cardiomyopathy in the absence of a PM. Four patients who developed a new cardiomyopathy were upgraded to biventricular pacing, leading to stabilization or improvement of LVEF. CONCLUSION In a relatively young and healthy cHB cohort, RV pacing is associated with a higher risk of developing a cardiomyopathy. These data confirm the deleterious effects of RV pacing on myocardial function in patients without pre-existing structural cardiac disease and has clinical implications to the management of patients with cHB.