Prolonged PR Interval and Outcome in Cardiac Resynchronization Therapy

Abstract

5. Lin J, Buhr KA, Kipp R. Effect of PR Interval on Outcomes Following Cardiac Resynchronization Therapy: A Secondary Analysis of the COMPANION Trial. J Cardiovasc Electrophysiol. 2017;28(2):185-91. References DOI: 10.5935/abc.20190101 Dear Editor We read the article “Baseline Prolonged PR Interval and Outcome of Cardiac Resynchronization Therapy: A Systematic Review and Meta-analysis” by Rattanawong et al.1 with great interest. The authors investigated the effect of prolonged PR interval on composite outcome among patients who received cardio resynchronized therapy. The authors conclude that prolonged PR is associated with worse outcome in this population. I would like to commend the authors for performing a systematic review and meta-analysis on this topic. The effect of prolonged PR interval was well-known in the general population. However, in this specific population, the answer is unclear and was in needed for answers, given almost half of the patients with cardiac resynchronization therapy (CRT) had 1st degree AV block.2 Although several previous studies reported a negative impact on the cardiovascular outcome, they were retrospective cohort and was limited by a relatively small number of participants. Nevertheless, the authors demonstrated a good systematic review and performed the random-effect model with statistical perfection. However, as the authors mentioned in the article, this meta-analysis has a limitation regarding the number of the included studies. Also, there is a difference in the cut-point for prolonged PR interval among the included studies. Although the study by Friedman et al. was the only study that used the cut-point of 230 ms instead of 200 ms, they have the most included participants and has the most weight percentage in all three forest plots. We thought that this is a crucial point as a change in risk ratio of the study by Freidman et al.3 could potentially change the overall pooled RR of the meta-analysis.