Reversal of Pacing-Induced Cardiomyopathy Following Cardiac Resynchronization Therapy

Abstract

Objectives: This study sought to determine the extent, time course, and predictors of improvement following cardiac resynchronization therapy (CRT) upgrade among pacing-induced cardiomyopathy (PICM) patients.

Background: PICM is an important cause of heart failure in patients exposed to frequent right ventricular (RV) pacing. CRT may reverse PICM.

Methods: We retrospectively studied 1,279 consecutive patients undergoing CRT procedures between 2003 and 2016. Patients undergoing CRT upgrade from a dual-chamber or single-chamber ventricular pacemaker for PICM were included. PICM was defined as decrease of ≥10% in left ventricular ejection fraction (LVEF), resulting in LVEF <50% among patients experiencing ≥20% RV pacing without an alternative cause of cardiomyopathy. Severe PICM was defined as pre-upgrade LVEF ≤35%. Clinical, electrocardiographic, and echocardiographic characteristics associated with both the extent of LVEF recovery and with post-upgrade LVEF of >35% among those with severe PICM were identified.

Results: Of 69 PICM patients, LVEF improved from 29.3% to 45.3% over a median 7.0 months. Of 54 patients with severe PICM, 39 (72.2%) improved to LVEF >35% over a median 7.0 months. Most improvement occurred within the first 3 months, although improvement continued over the remainder of the first year. In linear regression, narrower native QRS was associated with greater LVEF improvement following CRT upgrade (+2.00% per 10-ms decrease; p = 0.05).

Conclusions: CRT is highly efficacious in reversing PICM, with 72% of severe PICM patients achieving LVEF >35% and most of the improvement occurring within 1 year. These data support initial upgrade to a CRT pacemaker with consideration of further upgrade to CRT defibrillator after 1 year if LVEF remains ≤35%.

Keywords: biventricular pacing; cardiac resynchronization therapy; heart failure; pacing; pacing-induced cardiomyopathy.