Non-apical pacing: the right place to the right patient

We would like to congratulate Wang et al.1 for conducting a well-designed randomized trial that aimed at examining the superiority of pacing the right ventricular outflow tract (RVOT) over the traditional right ventricular apex (RVA). The authors looked at left ventricular (LV) regional wall motion performance as assessed by echocardiography and found that RVA pacing was associated with more dyssynchrony and LV wall motion abnormalities. However, there was no difference observed between the groups with respect to the LV ejection fraction (LVEF) after 12 months of follow-up (63.4 ± 4.3 vs. 63.2 ± 5.0% in the RVOT and the RVA pacing groups, respectively). Notably, only patients with normal baseline LVEF were included in the study. Therefore, the findings of Wang et al. are not unexpected and are actually in line with our meta-analysis that was recently published in Europace.2 By extracting the data from five randomized studies of patients in whom LVEF at baseline was ≥40–50% we were able to show no differences in the pooled LVEF at the end of-follow-up. Importantly, we demonstrated that non-apical pacing had significant beneficial effect on LVEF at the end of follow-up in patients who had low LVEF at baseline as compared with RVA pacing. Thus, in line with current cardiac resynchronization therapy guidelines, it seems that the option of RVOT pacing should be reserved for patients with low baseline LVEF. With that in mind, the advantage observed in wall motion performance by RVOT pacing may not correlate with important clinical endpoints such as mortality. No study till date has shown superiority for non-apical pacing in terms of survival. We therefore suggest that a potential benefit of non-apical pacing should be further examined in a large randomized trial that will look at ‘harder’ endpoints in selected patients with low baseline LVEF. Conflict of interest: none declared.