Electrical Dyssynchrony Mapping and Optimization of Nonresponders in Patients Programmed with the Adaptive Cardiac Resynchronization Therapy Algorithm.

Abstract

Background: The Adaptive cardiac resynchronization therapy (CRT) algorithm (aCRT) provides important clinical benefit. However, a significant number of patients are nonresponders.

Objective: The purpose of this study was to quantify electrical synchrony in patients programmed with aCRT and to assess the effect of optimization on nonresponders.

Methods: We studied 125 patients programmed with aCRT and measured electrical synchrony at multiple device settings using novel electrical dyssynchrony mapping (EDM) technology. Electrical synchrony was quantified as cardiac resynchronization index (CRI), a measure that analyzes areas between multiple pairs of anterior and posterior electrograms and calculates synchrony normalized to native rhythm.

Results: CRI improved from baseline aCRT settings to optimal settings based on EDM (56±29% vs 92±12%, p<0.001). Patients programmed with LV-only aCRT (Group 1, n=68) had a greater CRI (62±25% vs 48±31%, p=0.014) than patients programmed with biventricular (BiV) aCRT (Group 2, n=57). In Group 1 and Group 2 respectively, optimal CRI during sequential BiV (92±13%, 93±9%) and LV-only (92±6%, 91±7%) pacing was significantly (p<0.001) greater than baseline aCRT CRI. In a subset of 53 nonresponders optimized using EDM there were significant improvements in CRI (37±25%, p<0.0001), LV ejection fraction (6.2±6.6%, p<0.0001), end-diastolic volume (9.5±28.2 ml, p=0.015), end-systolic volume (13.4±24.9 ml, p<0.001), and transverse (1.5±4.4%, p=0.014), longitudinal (1.0±2.5%, p=0.003) and circumferential (2.6±8.5%, p=0.047) strain.

Conclusion: Electrical synchrony improves 56% with CRT using aCRT programming and 92% with EDM optimization. Optimization of aCRT-programmed non-responders results in significant improvements in LV size and systolic function offering the possibility of converting CRT nonresponders into responders.