Atrial fibrillation after cardiac surgery: Risk factors and their temporal relationship in prophylactic drug strategy decision

Abstract 

Objective

Postoperative atrial fibrillation (AF) is a vexing problem in cardiac surgery. Our aim was to identify risk factors between surgical procedures, all having cardiopulmonary bypass (CPB) in common, and how AF contributes to early and late mortality.

Methods

Patients were reviewed during a 10-year period, comprising coronary artery bypass grafting (CABG, n=7056), aortic valve replacement (AVR, n=690) and their combination (COMB, n=688). The study assessed 43 variables of which pre-/intraoperative data were evaluated for uni/multivariate analysis in relation to AF and type of surgery. Data were reviewed versus hospital and 1-year mortality; the latter being obtained from the Swedish population registry.

Results

The surgery subgroups exhibited obvious differences. The overall incidence of AF was 25.6%, ranging from 22.7% for CABG to 44.0% for COMB procedures. Numerous interaction patterns were seen among the analyzed parameters. In multivariate fashion, age was encountered in all groups, whereas coronary disease superimposed risk factors with reference to myocardial conditions at CPB weaning. Postoperative AF increased the length of hospitalization, whereas it did not affect hospital mortality. In CABG patients only, AF gave rise to increased 1-year mortality (p<0.001).

Conclusions

In addition to the accepted risk factors of AF, primarily age, we emphasize the importance of considering details at CPB weaning, a correlation that was coronary specific. The weaning period hides valuable information that can be useful for more specific AF-prophylactic strategies. The AF-related increase in late mortality after CABG but not after valve procedures is intriguing, and draws attention to possible AF recurrence during patient follow-up and management.

Keywords: Atrial fibrillation, Adult, Cardiac surgery, Coronary artery bypass grafting, Cardiopulmonary bypass, Embolism