Key result
Biventricular pacing cuts early systolic dyssynchrony ~76% vs RVA pacing, predicting preserved LV function.
Why the study?
It remains unknown whether early pacing-induced systolic dyssynchrony can predict long-term reduction of left ventricular systolic function in patients with standard pacing indications and normal LVEF.
Does early pacing-induced systolic dyssynchrony predict long-term reduction of LV systolic function in patients with normal LVEF requiring pacing?
RCT (n=177)
randomized
Does early pacing-induced systolic dyssynchrony predict long-term reduction of LV systolic function in patients with normal LVEF requiring pacing?
Early pacing-induced systolic dyssynchrony and right ventricular apical pacing are independent predictors of long-term deterioration of left ventricular systolic function in patients with normal baseline LVEF.
Early DYS may flag long-term LV deterioration risk in paced patients; extends PACE observations but remains hypothesis-generating pending prospective validation.
AIMS: Biventricular (BiV) pacing was superior to right ventricular apical (RVA) pacing at extended follow-up in the Pacing to Avoid Cardiac Enlargement (PACE) trial. Early pacing-induced systolic dyssynchrony (DYS) might be related to mid-term result. However, it remains unknown whether early pacing-induced DYS can predict long-term reduction of left ventricular (LV) systolic function. METHODS AND RESULTS: Patients with standard pacing indications and normal LV ejection fraction (LVEF) were randomized either to BiV (n = 89) or RVA (n = 88) pacing. Seventy-four patients in the RVA group and 72 in the BiV pacing group completed follow-up longer than 2 years. Serial echocardiography was performed with DYS assessed by tissue Doppler imaging, and the early pacing-induced DYS was defined as >33 ms by using standard deviation of the time to peak systolic velocity (Dyssynchrony Index) in a 12-segment model of LV at 1 month. There were 46 (32%) patients having early pacing-induced DYS that was more prevalent in the RVA pacing group than that in the BiV pacing group (50.7 vs. 12.3%, χ(2) = 25.1, P < 0.001) despite the similar DYS between the two groups at baseline (30 ± 13 vs. 26 ± 11 ms, P = 0.051). At a median follow-up of 4.8 years, patients developing early DYS had lower LVEF (53.2 ± 9.4 vs. 60.9 ± 8.0%, P < 0.001) and larger LV end-systolic volume (40.3 ± 23.7 vs. 29.3 ± 13.4 mL, P < 0.001) than those without DYS. Significant EF reduction (defined as ≥5%) occurred in 71.7% (33 in 46) of patients with DYS, but only in 30% (30 in 100) in those without DYS (χ(2) = 22.4, P < 0.001). Further analysis showed that both DYS at 1 month [odds ratio (OR): 3.113, P = 0.013] and RVA pacing (OR: 7.873, P < 0.001) independently predicted the deterioration of LV systolic function with pacing period of 4.8 years. CONCLUSION: Early pacing-induced DYS is a significant predictor of reduction of LV systolic function for long-term pacing, which could be prevented by BiV pacing at relatively long-period follow-up. CLINICAL TRIAL REGISTRATION: Centre for Clinical Trials number, CUHK_CCT00037 (URL: http://www.cct.cuhk.edu.hk/Registry/publictrialrecord.aspx?trialid=CUHK_CCT00037).
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Fang et al. (2015) conducted an RCT in Standard pacing indications and normal LV ejection fraction (n=177). Biventricular (BiV) pacing vs. Right ventricular apical (RVA) pacing was evaluated on Early pacing-induced systolic dyssynchrony (DYS) at 1 month (p=<0.001). Biventricular pacing reduced early pacing-induced systolic dyssynchrony compared to right ventricular apical pacing (12.3% vs 50.7%, P<0.001), predicting long-term LV function deterioration.
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