Evaluation of left ventricular function and mitral regurgitation during left ventricular-based pacing in patients with heart failure

Background: Beneficial effects of left ventricular (LV)-based pacing on acute hemodynamic parameters were reported in several series, but only a few studies examined the long-term effects of this new pacing procedure. Aims: To assess long-term effects of permanent LV-based pacing on LV function and mitral regurgitation (MR) in patients with refractory congestive heart failure (CHF). Methods: A prospective evaluation of LV function and MR was performed in 23 patients with severe but stable CHF and left bundle branch block (mean QRS: 186±31 ms) by radionuclide and echocardiographic techniques at baseline and 6 months after implantation of a permanent LV-based (LV alone: 13 patients; biventricular: 10 patients) pacemaker programmed either in a DDD mode (sinus rhythm; n - 14) or in a VVIR mode (atrial fibrillation; n - 9). Results: Compared to baseline, the 6 months follow-up visit demonstrated a significant increase in radionuclide derived LV ejection fraction from 23.3±7 to 26.2±7% (P < 0.01) and in echocardiographic LV fractional shortening from 13±4 to 16±6% (P < 0.05), without any change in cardiac index, a significant decrease in LV end-diastolic diameter (from 73.2±6 to 71.2±7 mm; P < 0.05), end-systolic diameter (from 63.6±6 to 60.2±8 mm; P < 0.05) and color Doppler MR jet area (from 11.5±6 to 6.6±4 cm1; P < 0.001). A comparison of patients with LV pacing alone and patients with biventricular pacing showed similar beneficial effects of pacing on MR severity in the two subgroups and a non-significant trend for a better improvement of LV function during biventricular pacing. Conclusion: Thus, in patients with severe CHF and left bundle branch block, permanent LV-based pacing may significantly improve LV systolic function and decrease MR.