Biventricular Pacemaker Therapy Corrects Dyssynchrony In Non-Obstructive Hypertrophic Cardiomyopathy

Background. Previous studies have reported dyssynchrony using Tissue Doppler in patients with hypertrophic cardiomyopathy (HCM). In this study we assessed dyssynchrony using speckle tracking echocardiography (STE) in patients with non-obstructive hypertrophic cardiomyopathy vs a healthy control group and in a subgroup of highly symptomatic patients evaluated the acute effects of biventricular pacing on STE and Tissue Doppler (TDI) derived measures of dyssynchrony. Methods. We studied 48 healthy controls (age 48 ±18yrs, 22 males, LVEF 63 ±5%, QRS 86 ±7ms) and 57 patients with HCM (age 54 ±11yrs, 38 males, LVEF 61 ±7%, QRS 110 ±36ms). A subgroup of 15 symptomatic patients with HCM (Peak VO2<60% predicted) underwent biventricular pacing (age 53 ±12yrs, 12 males, LVEF 61 ±7%, QRS 110 ±32ms). Echocardiography was performed with the pacemaker off (VVi30) and on (DDDR, AV delay 90ms, LV-RV delay 0 – 4ms). Using STE, the standard deviation (SD) in time to peak longitudinal strain (Tϵ-SD), the time to peak longitudinal systolic velocity (Ts) for each of 18 left ventricular segments and the SD of this timing (Ts-SD) was derived. Using TDI dyssynchrony was assessed from the SD of Ts for the basal six segments and the maximum difference in Ts between any two basal segments (Ts-peak[basal]). Results. Using STE, Tϵ-SD (54.99 ±33.61ms vs 24.55 ±21.18ms p<0.001), Ts-SD (71.06 ±32.32ms vs 46.17 ±21.50ms p<0.001) and Ts (155.74 ±23.14ms vs 123.71 ±11.25ms p<0.001) were greater in HCM than in controls. Using STE we demonstrated that biventricular pacing significantly reduced Tϵ-SD and Ts-SD to values similar to those observed in controls (Ts-SD p=0.13). Using TDI we demonstrated that biventricular pacing significantly reduced Ts, Ts-SD, and Ts-peak[basal]. See Table . (All values expressed as mean ±SD) Conclusion. Cardiac resynchronisation therapy significantly reduced dyssynchrony in symptomatic patients with non-obstructive HCM as demonstrated using STE and TDI. Table