Left ventricular resynchronization predicted by individual performance of right and left univentricular pacing: a study on the impact of sequential biventricular pacing on ventricular dyssynchrony.

Abstract

There is increasing evidence that improvement in left ventricular (LV) mechanical dyssynchrony is correlated with LV functional recovery in patients undergoing cardiac resynchronization therapy (CRT). Recent studies have suggested that sequential biventricular pacing may be important for further optimizing parameters of ventricular dyssynchrony.The purpose of this study was to evaluate the acute effect of varying sequential biventricular pacing settings on echocardiographic parameters of ventricular dyssynchrony and to identify predictors of the optimal setting.Twenty-nine patients referred for CRT were evaluated with standard echocardiography and tissue Doppler imaging before and after implantation. Indices of interventricular and intraventricular dyssynchrony were assessed for trends during simultaneous and sequential biventricular pacing.Twelve patients (41%) demonstrated linear trends of decreasing systolic dyssynchrony index with increasing LV preactivation. The mean additional decrease in dyssynchrony index at the optimized setting compared with simultaneous biventricular pacing was 26% (P <.04). Twenty-two patients (76%) demonstrated linear trends to decreasing interventricular dyssynchrony with increasing LV preactivation. The trends were strongly correlated with the magnitude of difference of the respective dyssynchrony measures in right ventricular only and LV only univentricular pacing. A significantly, superior capacity of LV only pacing for ventricular resynchronization was found in this subgroup of patients.In patients undergoing CRT, differences in the performance of univentricular pacing are associated with linear trends in ventricular dyssynchrony parameters in sequential biventricular pacing. Quantitative differences in LV univentricular pacing impact on the capacity of biventricular pacing to correct ventricular dyssynchrony.