Biventricular versus left ventricular pacing in heart failure

Abstract

Cardiac resynchronisation therapy (CRT) using biventricular (BiV) pacing has proved its effectiveness to correct myocardial asynchrony and improve clinical status of patients with severe congestive heart failure (CHF) and widened QRS. Despite a different effect on left ventricular electrical dispersion, left univentricular (LV) pacing is able to achieve the same mechanical synchronisation as BIV pacing in experimental studies and in humans. This results in clinical benefits of LV pacing at mid-term follow-up, with significant improvement in functional class, quality of life and exercise tolerance at the same extent as those observed with BiV stimulation in non randomized studies. Furthermore these benefits are obtained at lesser costs and with conventional dual-chamber devices. However, LV pacing has to be compared to BIV pacing in randomized trials before being definitely considered as a cost-effective alternative to BiV pacing. Our study was designed to examine whether LV pacing is as safe and effective as BiV pacing in CRT for heart failure patients. Paired data were collected on 20 patients (18 males, age 54.3 years +/-18) with refractory heart failure symptoms (15 ischemic, 5 dilated), sinus rhythm, and LBBB with QRS duration >120 ms. Patients were randomized to an initial 8weeks of either BiV or LV pacing, followed by 8 weeks of the other pacing mode, in a blinded cross-over design. Echocardiography was used to optimize atrioventricular delay for both modes and right ventricular–left ventricular offset for BiV mode. Our study demonstrated equivalent improvement in both pacing modes after 8 weeks of pacing regarding NYHA functional class, LV dimensions and ejection fraction and Scores on Minnesota living with heart failure questionnaire, while improvement in 6 min walk distance was significantly better in LV only pacing, the results were consistent with similar studies which reported that LV pacing was equal and, sometimes, superior to biventricular pacing in patients with underlying LBBB-type conduction delay. Our study showed that LV pacing appeared to be associated with clinical and echocardiographic benefits similar and may be better than BiV pacing at mid-term follow-up Although our study involved small number of patients in a single center and the cross over design raises the issue of carry over or period effect, but our data suggest that such economically more cost beneficial approach deserves further consideration as an acceptable alternative to BiV pacing in some patients with severe CHF and LBBB.