Improvement of Reverse Remodeling Using Electrocardiogram Fusion-Optimized Intervals in Cardiac Resynchronization Therapy: A Randomized Study

Abstract

Objectives: The aim of this study was to compare patient response to cardiac resynchronization therapy (CRT) using fusion-optimized atrioventricular (AV) and interventricular (VV) intervals versus nominal settings.

Background: The additional benefit obtained by AV- and VV-interval optimization in patients undergoing CRT remains controversial. Previous studies show short-term benefit in hemodynamic parameters; however, midterm randomized comparison between electrocardiogram optimization and nominal parameters is lacking.

Methods: A group of 180 consecutive patients with left bundle branch block treated with CRT were randomized to fusion-optimized intervals (FOI) or nominal settings. In the FOI group, AV and VV intervals were optimized according to the narrowest QRS, using fusion with intrinsic conduction. Clinical response was defined as an increase >10% in the 6-min walk test or an increment of 1 step in New York Heart Association functional class. The left ventricular (LV) remodeling was defined as >15% decrease in left ventricular end-systolic volume (LVESV) at 12-month follow-up. Additionally, patients with LVESV reduction >30% relative to baseline were considered super-responders; by contrast, negative responders had increased LVESV relative to baseline.

Results: Participant characteristics included a mean age of 65 ± 10 years, 68% male, 37% with ischemic cardiomyopathy, LV ejection fraction 26 ± 7%, and QRS 180 ± 22 ms. Baseline QRS was shortened significantly more by FOI, compared with nominal settings (-56.55 ± 17.65 ms vs. -37.81 ± 22.07 ms, respectively; p = 0.025). At 12 months, LV reverse remodeling was achieved in a larger proportion of the FOI group (74% vs. 53% [odds ratio: 2.02 (95% confidence interval: 1.08 to 3.76)], respectively; p = 0.026). No significant differences were observed in clinical response (61% vs. 53% [odds ratio: 1.43 (95% confidence interval: 0.79 to 2.59)], respectively; p = 0.24).

Conclusions: Device optimization based on FOI achieves greater LV remodeling, compared with nominal settings. (ECG Optimization of CRT: Evaluation of Mid-Term Response [BEST]; NCT01439529).

Keywords: atrioventricular; interventricular delay optimization; ventricular remodeling.