Right Ventricular Response to Cardiac Resynchronization Therapy: A Three-Dimensional and Speckle Tracking Echocardiographic Study

Cardiac resynchronization therapy (CRT) induces left ventricle reverse remodeling; however, its effects on right ventricular (RV) volumes and function were not well described. This study aimed to assess the effects of CRT on RV. Of 112 patients, 63 enrolled with a mean age of 62.77 ± 7.23 years, including 40 males (63.5%). All patients met criteria for CRT implantation and were followed at 3-month and 6-month intervals. Standard 2-dimensional/3-dimensional (3D) echocardiography and speckle-tracking analyses were conducted for assessment of LV and left atrium (LA). RV maximum diameters, tricuspid lateral annular systolic velocity, tricuspid annular plane systolic excursion, fractional area change, RV global (RV 4-chamber strain (RV4CSL), and RV free wall strain (RVFWSL), in addition to 3D echocardiographic assessment of RV, were done before CRT implantation and at follow-up visits. Mean follow-up period was 6.76 ± 1.25 months. A total of 48 patients (76.2%) were LV responders (LVR) whereas the rest were nonresponders (LVNR). Both groups had similar baseline characteristics, risk factors, device implantation, and programming values. Only LVR had significant reduction in RV basal diameter, together with significant improvement of RV systolic performance: systolic velocity, fractional area change, RV4CSL, RVFWSL, and 3D-derived RV volumes and ejection fraction, compared with baseline values. In addition, pulmonary arterial systolic pressure decreased in LVR with reduction of tricuspid regurgitation severity. LV response, percentage change of RV4CSL, LA end-systolic volume index, and LA emptying fraction at 3-month follow-up were the most independent predictors of RV response by multivariate analysis. Reduced left ventricular end-systolic volume >13.5% had 92.3% sensitivity and 81.8% specificity. In conclusion, CRT-induced RV reverse remodeling and improved RV-arterial coupling. These effects were associated with left side response to CRT.