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.