SYNTAX score predicts postoperative atrial fibrillation in patients undergoing on-pump isolated coronary artery bypass grafting surgery

To the Editor,

We read the published article entitled “SYNTAX score predicts postoperative atrial fibrillation in patients undergoing on-pump isolated coronary artery bypass grafting surgery” published in Anatol J Cardiol 2015 Nov 18 (1). with great pleasure. I congratulate the authors for this excellent study; however, we would like to highlight some points regarding this article. In their study, the authors reported that SYNTAX score, age, and chronic obstructive pulmonary disease are independently related to postoperative atrial fibrillation (PoAF). PoAF definition is a controversial issue and not clearly identified in the literature. According to 2012 European Society of Cardiology guidelines for diagnosis and treatment of atrial fibrillation, absolutely irregular RR intervals and absence of consistent P waves on the surface electrocardiogram (ECG) lasting long enough for 12-lead ECG to be recorded, or at least 30 seconds on rhythm strip, should be considered AF (2). The authors defined PoAF as an AF episode following surgery lasting longer than 5 minutes. How were patients who had AF lasting less than 5 minutes classified ? In addition, it was reported that Geçmen et al. (1) followed the patients with continuous telemetry for between 72 and 96 hours after surgery; however, mean length of stay in hospital was not mentioned. PoAF is known to increase length of hospital stay, sometimes extending to 7 to 10 days. In this context, we could expect to find a difference in length of hospital stay between patients with and without PoAF and authors should report this data.

Another issue we would like to discuss is risk factors for PoAF. In this study, the authors evaluated a number of risk factors that might be associated with PoAF. However, obstructive sleep apnea, obesity, and inadequate use of beta blockers or renin angiotensin aldosterone (RAS) blockers have also been shown to be independent predictors of new onset PoAF (3, 4). These risk factors should be included in statistical analyses. We suppose that many patients in this study might use RAS and beta blockers since they had many cardiovascular diseases such as hypertension, heart failure, and acute coronary syndrome. We think that adding these variables to statistical analyses may change predictive value of SYNTAX score for PoAF.