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:∆LVESV correlated with ∆SDAT (P = .007), but not with ∆QRS 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% vs -13% ± 29%; P = .005). Patients with ≥10% improvement in SDAT had greater ∆EF (11 ± 9 units vs 4 ± 9 units; P = .010) and ∆LVESV (-33% ± 26% vs -6% ± 34%; P = .001). SDAT ≥35 ms predicted ∆EF, while ∆SDAT, sex, and left bundle branch block predicted ∆LVESV. In 34 patients without class I indication for CRT, SDAT ≥35 ms (P = .015) and ∆SDAT ≥10% (P = .032) were the only predictors of ∆EF. 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.