Effect of Biventricular Pacing on Diastolic Dyssynchrony

ObjectivesThis study sought to examine the changes in diastolic dyssynchrony with cardiac resynchronization therapy (CRT).BackgroundLittle is known about the effect of CRT on diastolic dyssynchrony.MethodsConsecutive heart failure patients (n = 266, age 65.7 ± 10.0 years) underwent color-coded tissue Doppler imaging at baseline, 48 h, and 6 months after CRT. Systolic and diastolic dyssynchrony were defined as maximal time delay in peak systolic and early diastolic velocities, respectively, in 4 basal LV segments. CRT responders were defined as those with ≥15% decrease in LV end-systolic volume at 6 months.ResultsBaseline LVEF was 25.2 ± 8.1%; 63.5% patients were CRT responders. Baseline incidence of systolic and diastolic dyssynchrony, and a combination of both was 46.2%, 51.9%, and 28.6%, respectively. Compared to nonresponders, responders had longer baseline systolic (79.2 ± 43.4 ms vs. 45.4 ± 30.4 ms; p < 0.001) and diastolic (78.5 ± 52.0 ms vs. 50.1 ± 38.2 ms; p < 0.001) delays. In follow-up, systolic delays (45.4 ± 31.6 ms at 48 h; 38.9 ± 26.2 ms at 6 months; p < 0.001) and diastolic delays (49.4 ± 36.3 ms at 48 h; 37.7 ± 26.0 ms at 6 months; p < 0.001) improved only in responders.ConclusionsAt baseline: 1) diastolic dyssynchrony was more common than systolic dyssynchrony in HF patients; 2) nonresponders had less baseline diastolic dyssynchrony compared to responders. After CRT: 1) diastolic dyssynchrony improved only in responders. Further insight into the pathophysiology of diastolic dyssynchrony and its changes with CRT may provide incremental information on patient-specific treatments.