Background
Atrial fibrillation (AF) is a common arrhythmia in the general population and is more common in specific conditions such as cardiac and non-cardiac surgery [1,2]. AF following surgery could occur in patients who were or were not previously diagnosed with AF. Post-operative atrial fibrillation (POAF) is defined as the development of AF in the postoperative period in a patient who was not previously diagnosed with AF [2,3].
Focusing on POAF following cardiac surgeries is important since it is considered a common complication affecting patients following abundant surgical procedures including coronary artery bypass grafting (CABG), valve surgery, combined CABG and valve surgery, congenital defects surgery, and even percutaneous coronary revascularization but with a much lower risk than major surgical intervention [3-6]. The occurrence of POAF increases in correlation with increasing invasiveness of cardiac surgery, and may reach up to 60%, usually appearing within the first 6 days after surgery with a peak in the 2nd-4th days [4-6].
POAF is associated with major morbidities such as prolonged mechanical ventilation support, postoperative stroke, myocardial infarction, cardiac arrest, permanent pacemaker, respiratory failure, pneumonia, gastrointestinal complications, acute kidney injury, and a new onset of dialysis. Furthermore, POAF leads to a longer hospital and intensive care unit stay, higher treatment costs, hospital readmission, and most importantly, 2 folds of increased mortality [6-8].
Risk factors that were reported to correlate with increased incidence of POAF, were derived from epidemiological studies, and can be divided into 3 main groups: preoperative, intraoperative and postoperative factors [9,10] . In the last 20 years, research has expanded in the field of POAF and several modifications have been implemented to perioperative management and surgical techniques, in an attempt to decrease POAF incidence or its subsequent complications. However, more progress needs to be made [11] . The aim of this study is to evaluate preoperative, intra-operative risk factors and predictors of occurrence of overall AF following cardiac surgery including patients previously diagnosed and who were not previously diagnosed with AF (POAF).