Atrial Fibrillation Post Cardiac Surgery: Incidence, Predisposing Factors And Prognostic Implications

BACKGROUND & OBJECTIVES: Atrial fibrillation (AF) is the most common arrhythmia occurring postcardiac surgery and is associated with significant morbidity, increased overall hospital stay and cost. Anecdotal observations suggest very low incidence in Pakistani patients undergoing cardiac surgery particularly coronary artery bypass graft surgery (CABG). The objective of this study was to assess the prevalence, morbidity & mortality of post cardiac surgery AF.METHODS: A prospective study of 201 consecutive patients undergoing cardiac surgery at a tertiary care center. Clinical characteristics and perioperative data was collected & analyzed. Patients were followed for presence or absence of atrial fibrillation till hospital discharge. RESULTS: The overall incidence of AF post cardiac surgery was 6.9 %. AF occurred in 9 of 187 patients undergoing CABG alone, 3 of 12 patients undergoing valve replacement and 2 of 2 undergoing combined procedures. Increased left atrial (LA) size had significant association with post cardiac surgery AF (p = 0.01) as did the use of dopamine and epinephrine post operatively (p = 0.03 & 0.002 respectively). In addition, significant association was also noted for valvular surgery (p = <0.001). Multiple logistic regression analysis revealed that increased LA size (odds ratio 0.08, 95% CI 0.008-0.99, p = 0.04) was the only independent predictor of post cardiac surgery AF with borderline significance for concomitant valvular surgery (odds ratio 0.89, 95% CI 0.79-0.99, p = 0.05). Mean hospital stay was significantly longer & overall cost was significantly higher in patients who developed AF (p = <0.001) in addition to higher overall mortality (p = 0.025).CONCLUSIONS: The incidence of AF post cardiac surgery was quite low in this study cohort. The occurrence of atrial fibrillation, albeit for short duration, was associated with higher all cause mortality, significantly longer hospital stay and higher overall cost.