924 Effect of left ventricular reverse remodeling after cardiac resynchronization therapy on left ventricular torsion in severe heart failure

Abstract

Background: Cardiac resynchronization therapy (CRT) has been used extensively in the therapeutic management of patients with drug-refractory heart failure. The LV torsion was proposed as one of the important markers of LV function. However, the effect of CRT on LV torsion was not still elucidated. Methods: Fourteen patients with severe heart failure who received CRT were studied. Apical 2-, 3and 4-chamber views were obtained by tissue Doppler imaging before and 6 months after CRT. Total 12 regions of interest were placed on mid and base of each apical view. Time interval from end-diastole to the timing of peak systolic velocity (TS) in each regions of interest was obtained and standard deviation of TS (TS-SD) was calculated as an index of LV asynchrony. After acquiring LV basal and apical short-axis images digitally, apical and basal rotation angles were calculated using newly developed custom software which tracked objects from one frame to the next frame based on pattern matching algorithm (two dimensional tissue tracking system, HITACHI, EUB-8500). The LV torsion was defined as net-difference between basal and apical rotation angle. LV ejection fraction (EF), LV end-diastolic volume and LV end-systolic volume (ESV) were assessed by the biplane Simpson’s equation. Results: Eight of 14 patients showed more than 10% reduction in ESV at 6 months after CRT (responders). The improvement of TS-SD was not different between responders and non-responders. The direction of LV apical and basal rotation was opposite in responders, on the other hand, that was same in non-responders. Consequently, LV torsion and LVEF in responders were significantly greater than those in non-responders (6.7±3.2 vs -0.1±2.9, 44.1±10.6 vs 15.3±5.3%, respectively, both p<0.05). Conclusions: The reduction of LV volume after CRT may contribute to increase LV torsion which related to the improvement of LV systolic function. 925 Two-dimensional tissue tracking technique can evaluate left ventricular dyssynchrony