Results:

Eleven studies met inclusion criteria (three randomized and eight observational trials), comparing incidence of POAF (primary outcome) and various postoperative adverse events (secondary outcomes) among 27,885 patients, 13,553 of whom received preoperative RASI treatment. A total of 7,018/27,855 patients (25.2%) developed POAF during a follow-up period that encompassed 30 postoperative days or duration of hospitalization. Only 3 of the 11 studies were randomized clinical trials (RCTs), collectively contributing 673 individual patients, or 2.4% of the systematic review population. Six studies enrolled patients undergoing CABG, whereas five enrolled patients undergoing either CABG or valve surgery. Compared to control, preoperative RASI treatment showed no significant reduction in risk of POAF (OR, 1.04 [0.91-1.19]), although significant variability between studies was observed (I² = 72%). Among secondary outcomes, no significant differences in stroke (OR, 0.86 [0.62-1.19]), death (OR, 1.07 [0.85-1.35]), composite of adverse cardiac events (OR, 1.04 [0.91-1.18]), or length of hospitalization were observed based on preoperative RASI status. Meta-regression analysis exploring individual covariates indicated that male sex significantly increased risk (z = 3.47) and concomitant beta-blocker treatment significantly decreased risk (z = -2.24) of POAF. Although two of the three RCTs showed significant protective effect of RASI against development of POAF, their statistical power was limited by a relatively small sample size.