Five RCTs were included in the review (574 participants, range 18 to 306). Two trials were single blinded and three trials were double blinded. Allocation concealment was adequate in two trials. All five trials were free of selective reporting, incomplete outcome data and other bias. There was no evidence of publication bias.
Four of the five included studies were parallel randomised trials and one was a crossover randomised trial. Follow-up ranged from two months to twelve months.
Meta-analysis showed no significant differences between left ventricular pacing and biventricular pacing in six-minute walk distance, quality of life improvement, peak oxygen consumption and New York Heart Association Class. There were discrepancies between the text and forest plots for New York Heart Association Class and quality of life improvement.
Pooled results for left ventricular ejection fraction (WMD 1.28, 95% CI -0.11 to 2.68, p=0.07) and left ventricular end-systolic volume (WMD -5.73, 95% CI -11.86 to 0.39, p=0.07) favoured biventricular pacing but the differences did not reach statistical significance.
Substantial heterogeneity was observed in New York Heart Association Class (Ι²=80%) and the authors performed a sensitivity analysis.