Effects of Cardiac Resynchronization Therapy on Left Ventricular Twist

Abstract

This study explored the effects of cardiac resynchronization therapy (CRT) on left ventricular (LV) twist, particularly in relation to LV lead position. LV twist is emerging as a comprehensive index of LV function. Eighty heart failure patients were included. Two-dimensional echocardiography was performed at baseline, immediately after CRT, and at 6-month follow-up. Speckle-tracking analysis was applied to assess LV twist. The LV lead was placed preferably in a (postero)lateral vein, and at fluoroscopy, the position was classified as basal, midventricular, or apical. Response to CRT was defined as reduction of LV end-systolic volume>or=15% at 6-month follow-up. A control group comprised 30 normal subjects. Peak LV twist in heart failure patients was 4.8+/-2.6 degrees compared with 15.0+/-3.6 degrees in the control subjects (p<0.001). At 6-month follow-up, peak LV twist significantly improved only in responders (56%), from 4.3+/-2.4 degrees to 8.5+/-3.2 degrees (p<0.001). The strongest predictor of response to CRT was the improvement of peak LV twist immediately after CRT (odds ratio: 1.899, 95% confidence interval: 1.334 to 2.703, p<0.001). Furthermore, LV twist significantly improved in patients with an apical (from 4.3+/-3.1 degrees to 8.6+/-3.0 degrees, p=0.001) and midventricular (from 4.8+/-2.2 degrees to 6.4+/-3.9 degrees, p=0.038) but not with a basal (5.0+/-3.3 degrees vs. 4.1+/-3.2 degrees, p=0.28) LV lead position. Similarly, LV ejection fraction significantly increased in patients with an apical (from 26+/-7% to 37+/-7%, p<0.001) and midventricular (from 26+/-6% to 33+/-8%, p<0.001) but not with a basal (26+/-5% vs. 28+/-8%, p=0.30) LV lead position. An immediate improvement of LV twist after CRT predicts LV reverse remodeling at 6-month follow-up.