Background: In patients with left ventricular (LV) dysssynchrony, contraction that doesnâ??t fall into ejection period\n(LVEj) results in a waste of energy due to inappropriate contraction timing, which was now widely treated by\ncardiac resynchronization therapy(CRT). Myocardial Contraction Efficiency was defined as the ratio of Efficient\nContraction Time (ECTR) and amplitude of efficient contraction (ECR) during LVEj against that in the entire cardiac\ncycle. This study prospectively investigated whether efficiency indexes could predict CRT outcome.\nMethods: Our prospective pilot study including 70 CRT candidates, parameters of myocardial contraction timing\nand contractility were measured by speckle tracking echocardiography (STE) and efficiency indexes were calculated\naccordingly at baseline and at 6-month follow-up. Primary outcome events were predefined as death or HF hospitalization,\nand secondary outcome events were defined as all-cause death during the follow-up. 16-segement Standard deviation of\ntime to onset strain (TTO-16SD) and time to peak strain (TTP-16SD) were included as the dyssynchrony indexes.\nResults: According to LV end systolic volume (LVESV) and LV eject fraction(LVEF) values at 6-month follow-up,\nsubjects were classified into responder and non-responder groups, ECR (OR 0.87, 95%CI 0.78â??0.97, P < 0.05)\nand maximum longitudinal strain (MLS) (OR 2.22, 95%CI 1.36â??3.61, P < 0.01) were the two independent\npredictors for CRT response, Both TTO-16SD and TTP-16SD failed to predict outcome. Patients with poorer\nmyocardial contraction efficiency and better contractility are more likely to benefit from CRT.\nConclusions: STE can evaluate left ventricular contraction efficiency and contractility to predict CRT response.\nWhen analyzing myocardial strain by STE, contraction during LVEj should be highlighted.
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