Electrical dyssynchrony mapping and optimization of nonresponders in patients programmed with the adaptive cardiac resynchronization therapy algorithm

Cardiac resynchronization therapy optimization in nonresponders and incomplete responders using electrical dyssynchrony mapping

Alan J. Bank, MD; Kevin V. Burns, PhD; Christopher D. Brown, BA; Evan Walser-Kuntz, MS; Madeline A. Czeck, PhD; Robert G. Hauser, MD1; Jay D. Sengupta, MD

Abstract

Background

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

Objectives

The goals of this study were to quantify electrical synchrony in patients programmed with aCRT and to assess the echocardiographic effects of optimization in CRT nonresponders and incomplete responders.

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 on the basis of EDM (56%±29% vs 92%±12%; P<.001). Patients programmed with left ventricle (LV)–only aCRT (group 1, n=68 [54%]) had a higher CRI (62%±25% vs 48%±31%; P=.014) than did patients programmed with biventricular aCRT (group 2, n=57 [46%]). In group 1 and group 2, optimal CRI during sequential biventricular (92%±13% and 93%±9%, respectively) and LV-only (92%±6% and 91%±7%, respectively) pacing was significantly (P<.001) higher than CRI at baseline aCRT setting. In a subset of 53 nonresponders optimized using EDM, there were significant improvements in CRI (37%±25%; P<.0001), LV ejection fraction (6.2%±6.6%; P<.0001), end-diastolic volume (9.5±28.2 mL; P=.015), end-systolic volume (13.4±24.9 mL; P<.001), and transverse (1.5%±4.4%; P=.014), longitudinal (1.0%±2.5%; P=.003), and circumferential (2.6%±8.5%; P=.047) strain.

Conclusion

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