Changes in electrical dyssynchrony by body surface mapping predict left ventricular remodeling in patients with cardiac resynchronization therapy

BACKGROUND Electrical activation is important in cardiac resynchronization therapy (CRT) response. Standard electrocardiographic analysis may not accurately reflect the heterogeneity of electrical activation. OBJECTIVE We compared changes in left ventricular size and function after CRT to native electrical dyssynchrony and its change during pacing. METHODS Body surface isochronal maps using 53 anterior and posterior electrodes as well as 12-lead electrocardiograms were acquired after CRT in 66 consecutive patients. Electrical dyssynchrony was quantified using standard deviation of activation times (SDAT). Ejection fraction (EF) and left ventricular end-systolic volume (LVESV) were measured before CRT and at 6 months. Multiple regression evaluated predictors of response. RESULTS ALVESV correlated with ASDAT (P = .007), but not with AQRS duration (P = .092). Patients with SDAT >35 ms had greater increase in EF (13 8 units vs 4 9 units; P < .001) and LVESV (-34% 28 /0 vs 13 /0 29 /0; P = .005). Patients with >10% improvement in SDAT had greater AEF (11 9 units vs 4 9 units; P = .010) and ALVESV (-33% 26% vs 6% 34%; P = .001). SDAT >35 ms predicted AEF, while ASDAT, sex, and left bundle branch block predicted ALVESV. In 34 patients without class I indication for CRT, SDAT >35 ms (P = .015) and ASDAT >10% (P = .032) were the only predictors of AEF. CONCLUSION Body surface mapping of SDAT and its changes predicted CRT response better than did QRS duration. Body surface mapping may potentially improve selection or optimization of CRT patients.