Acute biventricular pacing after cardiac surgery has no influence on regional and global left ventricular systolic function

Abstract

Background: Cardiac resynchronization therapy has been shown to improve systolic function in patients with advanced chronic heart failure and electromechanical delay (QRS width > 120 ms). However, the effect of acute biventricular (BiV) pacing on perioperative haemodynamic changes is not well defined. In the present study, acute changes in regional left ventricular (LV) systolic function determined by tissue Doppler imaging (TDI) and global LV systolic function determined by the continuous cardiac output method were measured during various pacing configurations in patients with depressed LV systolic function undergoing heart surgery.

Methods: Twenty-six patients (age 68 +/- 8 years, 15 males) with depressed systolic LV function (LV ejection fraction <or=35%), symptomatic heart failure, and a QRS duration of > 120 ms undergoing temporary epicardial BiV pacing after aortocoronary bypass and valve surgery were included. QRS duration on surface electrocardiogram (ECG), TDI (systolic velocities of septal and lateral mitral annulus), cardiac index (CI), right atrial pressure, pulmonary artery pressure (PAP), and pulmonary capillary wedge pressure (PCW) were measured during various pacing configurations [no pacing (intrinsic rhythm), right atrial-biventricular (RA-BiV pacing), right atrial-left ventricular (RA-LV), right atrial-right ventricular (RA-RV), and AAI pacing].

Results: There were no differences in QRS duration during intrinsic rhythm, RA-BiV pacing, and AAI pacing. However, RA-LV and RA-RV stimulations showed a longer QRS duration (P < 0.01 vs. intrinsic rhythm, RA-BiV pacing, and AAI, respectively). Tissue Doppler velocities of the septal and lateral mitral annulus were comparable in all pacing modes. Neither CI nor PAP or PCW showed significant differences during the various pacing configurations. There was a positive correlation between regional (TDI) and global (CI) parameters of LV systolic function. Conclusions Biventricular pacing after heart surgery does not improve parameters of regional and global LV systolic function acutely in patients with heart failure and intraventricular conduction delay and, thus, may not reflect changes observed with chronic BiV pacing.