Abstract 17693: The Effect of Interventricular Delay on AV Optimization for Cardiac Resynchronization Therapy
Introduction: Left ventricular (LV) delay, as measured by the QLV interval, at the LV pacing site predicts a number of outcomes with CRT including the magnitude of reverse remodeling. It also identifies a subgroup of patients (pts) who benefit from atrioventricular optimization (AVO). Whether interventricular delay at CRT pacing sites is associated with better CRT response is unknown.
Hypothesis: Pacing at sites of long interventricular delay, as measured by RV-LV duration, increases LV reverse remodeling and the effectiveness of AVO.
Methods: This substudy of SMART-AV included 419 pts who were randomized to either an electrogram (EGM) based AVO (SmartDelay) or nominal AV delay (120 ms). The RV-LV interval was measured from the peaks of RV and LV EGMs in sinus rhythm. CRT response was defined prospectively as a > 15% reduction in left ventricular end-systolic volume (LVESV) from implant to 6 months.
Results: The cohort was 66% male, with a mean age of 66±11 years and LV ejection fraction of 28±9%. When grouped by quartiles based on interventricular delay, there was a progressive increase in the magnitude of change in LVESV and CRT response rate for the entire cohort (p’s < 0.01). AVO reduced LVESV progressively more than fixed AV delay as RV-LV prolonged (interaction p = 0.069), with the largest reduction in the longest RV-LV quartile (p=0.011, figure). This difference remained significant (p=0.032) after adjusting for baseline covariates including etiology of HF, LBBB, gender, NYHA, QRS duration, age and baseline LVESV. Pts in the longest RV-LV quartile had 2.8 times greater odds of CRT response with AVO compared to fixed AV delay (p = 0.07).
Conclusion: Baseline interventricular electrical dyssynchrony, as measured by RV-LV duration, predicts CRT reverse remodeling response. At long RV-LV intervals, AVO can increase the likelihood of a reverse remodeling with CRT. AVO and RV-LV optimized lead locations may work synergistically to maximize CRT response.
Author Disclosures: M.R. Gold: Research Grant; Modest; Boston Scientific. Y. Yu: Employment; Significant; Boston Scientific. J.P. Singh: Research Grant; Significant; St Jude. Consultant/Advisory Board; Modest; St Jude, Boston Scientific, Liva Nova, Biotronik, Medtronic, Impulse dynamics, Respicardia. K.M. Stein: Employment; Significant; Boston Scientific. Ownership Interest; Significant; Boston Scientific. U. Birgersdotter-Green: Honoraria; Modest; Biotronik. Honoraria; Significant; Medtronic, St Jude. Consultant/Advisory Board; Modest; Medtronic. N. Wold: Employment; Significant; Boston Scientific. T.E. Meyer: Employment; Significant; Boston Scientific. K.A. Ellenbogen: Research Grant; Significant; Boston Scientific, Medtronic. Speakers Bureau; Significant; Boston Scientific, Medtronic, St Jude, Biotronik. Honoraria; Significant; Medtronic, Boston Scientific, Biotronik. Consultant/Advisory Board; Significant; Medtronic, Boston Scientific.
- © 2016 by American Heart Association, Inc.