5. DISCUSSION
POAF is a frequent early complication of cardiac surgery2-7 . Nevertheless, it leads to increased in-hospital and long-term mortality rates3-5,8-10 and longed hospitalization6,10-12 . However, It should also be noted that atrial fibrillation is usually self-limited among patients suffering POAF without previous atrial arrhythmias episodes. About 15 to 30 percent convert within two hours and up to 80 percent the first 24 hours 2,39,40 . Indeed, the challenge is to design cost-effective preventive therapy with impact in lowering POAF incidence.
Our review provides additional information regarding the potential association between statin and POAF reduction rate. Considering all fourteen studies, statin pre-treatment reduced the incidence of POAF compared to placebo (OR 0.71; 95% CI: 0.60 to 0.85, p-value < 0.00001). Analyzing specific statin subclasses, atorvastatin was associated with lower incidence of POAF (OR 0.54; 95% CI: 0.41 to 0.70, p-value = 0.002; I2= 65%), but rosuvastatin did not (OR 0.90; 95% CI: 0.71 to 1.14, p-value = 0.38). At first analysis, it is conceivable that there is a real difference between the two subclasses of statin. However, we retain that the discrepancy in findings is due to the small number of participants and other important limitations of many trials present in the literature. Indeed, we decided to select only RCTs with ≥ 199 participants. Interestingly, the results were completely conflicting. Indeed, using the above “restrictions”, we found no statistically significant difference between statin pre-treatment and placebo (OR 0.89; 95% CI: 0.74 to 1.09, p-value = 0.26; I2= 74%). The same can be said for atorvastatin (OR 0.74; 95% CI: 0.54 to 1.03, p-value = 0.08; I2= 83%) and rosuvastatin versus placebo (OR 0.87; 95% CI: 0.68 to 1.12, p-value = 0,29; I2= 84%).
We retain that the severe heterogeneity present in our results reflects the wide distribution of POAF incidence in different studies. In fact, as previously reported, a variable number between 15 to 50 percent of patients who had valve surgery or CABG experienced POAF in the early postoperative period 2-7 .
Overall, the STICS trial was the study with the fewest biases38 . Considering statin-naive patients, the authors enrolled 1269 individuals (more than one-third of the total number present in our meta-analysis). They evaluated the outcomes systematically in a blinded manner and compared outcomes between the trial arms on an intention-to-treat basis. In this study, the initiation of rosuvastatin therapy (20mg/day) before cardiac surgery did not prevent the risk for POAF 38 . In addition, a significantly higher rate of postoperative acute kidney injury was noted (24.7 versus 19.3 percent; p = 0.005) 38 .
Thus, since our results match the STICS trial ones, we are confident to state that there are no differences between statin and placebo in reducing POAF. However, since high heterogeneity between studies, more randomized clinical trials with more participants are mandatory for final confirmation. The START-CABG trial is an ongoing study that will probably contribute to dispelling many doubts41 . Indeed, in this study, 2630 were randomized to receive high-dose of wide subclasses of statin or placebo given shortly before CABG. One of the valuable secondary end-points includes POAF. Thus, this trial will help to confirm or reject the current evidence.
Until then, based upon our results (different from the previous meta-analysis) 18,42 and possible kidney issues, we suggest avoiding statin pre-treatment in preventing POAF for statin-naive patients undergoing cardiac surgery.