Four RCTs (534 participants) were included. One (56 participants) was a crossover study. Follow-up appeared to range from six to 24 months.
There was no statistically significant difference between biventricular pacing and right ventricular pacing, in all-cause mortality (Ι²=31%, four trials), procedure related adverse events (Ι²=27%, three trials) or six minute walk test duration (Ι²=0%, three trials). There was a small increase in mean left ventricular ejection fraction associated with biventricular pacing (+2.6%, 95% CI 1.7 to 3.4, Ι²=53%, four trials).
In two trials, biventricular pacing was associated with modest but statistically significant reduction in quality of life (Minnesota Living with Heart Failure Questionnaire 2.72 fewer points, 95% CI 1.45 to 3.99, Ι²=0%). A third trial reported no change in quality of life using the SF-36 Health Status Scale.
In subgroup analyses, including only those studies with baseline left ventricular systolic dysfunction, results were similar to the main analyses for all-cause mortality (Ι²=0%, three trials), and for mean left ventricular ejection fraction (Ι²=58%). These studies also reported on cardiac mortality; there was some reduction favouring biventricular pacing but this did not reach statistical significance (Ι²=0%, three trials).