Effects of cardiac resynchronization therapy on left as well as right ventricular deformation parameters

Background. Cardiac resynchronization therapy has been proved to achieve reverse left ventricular (LV) remodeling in patients with advanced heart failure but effects on right ventricular (RV) function are not well established. The aim of this study was to analyse the evolution of LV as well as RV tissue Doppler / strain Doppler imaging (TDI/SRI) parameters after biventricular pacing (BVP). Methods. Thirty-three patients with dilated cardiomyopathy (NYHA class II or greater), left bundle branch block (QRS 120ms), and LV ejection fraction 35% were studied with TDI/SRI echocardiography before and after BVP. Intraventricular dyssynchrony was determined as the difference between the longest and shortest electromechanical coupling times in the basal septal, lateral, and posterior LV segments. Interventricular dyssynchrony was determined as the difference between electromechanical coupling times in the basal lateral RV segment and the most delayed LV segment. Velocity and strain traces from right ventricular free wall (basal and mid cavity) were processed in the apical 4-chamber view. Diastolic TDI values (Ew, Aw), peak systolic strain and systolic and diastolic strain rate values were determined. Results. At six months follow-up after BVP, patients functional status improved by one NYHA class or more and LVEF improved overall from 19.97.5% to 29.311.4%. A significant reduction in severity of tricuspid regurgitation and pulmonary artery pressure was also observed. Interventricular dyssynchrony by SRI was reduced from 82.429 ms to 36.523.4 ms (p<0.005) and intraventricular dyssynchrony from 7731.2 ms to 23.815.9 ms (p<0.001). The degree of dyssynchrony correlated significantly with the improvement in LVEF and LV end-diastolic diameter. An increase of Ew at basal RV level from -11.81.9 cm/s to -15.91.5 cm/s was shown (p<0.005). Peak systolic strain and systolic and early diastolic strain rate at basal RV level increased, respectively, from 20.36.5% to 30.57.4%, -2.81.9 cm/s to -4.71.5 sec-1, and 4.81.7 cm/s to 7.91.4 sec-1 (p<0.001). RV reverse remodeling was only observed in patients with highest degrees of LV dyssynchrony at baseline. Conclusions. Thus, by improving temporal LV asynchrony, BVP has a positive hemodynamic impact on LV as well as RV function.