The effect of right ventricular apical and non-apical pacing on the short- and long-term changes in left ventricular ejection fraction: a systematic review and meta-analysis of randomized-controlled trials

BACKGROUND The right ventricular apex (RVA) is the traditional lead site for chronic pacing but in some patients may cause impaired left ventricular (LV) systolic function over time. Comparisons with non-apical (RVNA) pacing sites have generated inconsistent results and recent meta-analyses have demonstrated unclear benefit due to heterogeneity across studies. METHODS AND RESULTS A systematic search for randomized controlled trials that compared LVEF outcomes between RVNA and RVA pacing was performed up to October 2014. Twenty four studies (n = 1628 patients) met the inclusion criteria. To avoid between study heterogeneity two homogenous groups were created; group one where studies reported a difference (in favor of RVNA pacing) and group two where studies reported no difference between pacing sites. For group one weighted mean difference (WMD) between RVNA and RVA pacing in terms of LVEF at follow-up was 5.40% (95% CI: 3.94 to 6.87), related in part to group one's RVA arm demonstrating a significant reduction (mean loss -3.31%; 95% CI: -6.19 to -0.43) in LVEF between study baseline and end of follow-up. Neither of these finding were seen in group two. Weighted regression modeling demonstrated that inclusion of poor baseline LVEF (<40%) in combination with greater than 12 months follow-up was three times more common in group one compared to group two (weighted RR 2.82; 95% CI 1.03 - 7.72; P = 0.043). CONCLUSIONS In patients requiring chronic right ventricular pacing where there is inclusion of impaired baseline LVEF (