COMBAT is a prospective multicenter randomized double blind crossover study. Patients with New York Heart Association functional class (FC) II-IV, left ventricular ejection fraction (LVEF) <40 % , and AV block as an indication for pacing were enrolled. All patients underwent biventricular system implantation and then were randomized to receive successively (group A) RVP-BiVP-RVP, or (group B) BiVP-RVP-BiVP. At the end of each 3-month crossover period, patients were evaluated according to Quality of Life (QoL), FC, echocardiographic parameters, 6-Minute Walk Test (6MWT), and peak oxygen consumption (VO2max). Sixty patients were enrolled, and the mean follow-up period was 17.5 ± 10.7 months. There were significant improvements in QoL, FC, LVEF, and left ventricular end-systolic volume with BiVP compared with RVP. The effects of pacing mode on 6MWT and VO2max were not significantly different. Death occurred more frequently with RVP.
In patients with systolic HF and AV block requiring permanent ventricular pacing, BiVP is superior to RVP and should be considered the preferred pacing mode.