Postoperative atrial fibrillation after isolated coronary artery bypass grafting: The role of previous clinically silent SARS-CoV-2 infection

Aim: Postoperative atrial fibrillation (POAF) is a common complication after coronary artery bypass grafting (CABG). Although the cardiovascular effects of symptomatic COVID-19 are well described, whether prior asymptomatic SARS-CoV-2 infection increases postoperative atrial vulnerability remains uncertain.

Materials and Methods: This retrospective cohort study included 64 adults who underwent isolated CABG in 2021 – 2022. Patients were classified as having prior asymptomatic SARS-CoV-2 infection (n = 34) or no documented prior infection (n = 30). The primary endpoint was new-onset POAF during the index hospitalization. Additional observations included POAF onset, discharge rhythm, and atrial fibrillation-related readmission within 10 days. No a priori sample-size calculation was performed for this fixed cohort. Analyses were unadjusted because only nine POAF events occurred, precluding reliable multivariable modeling.

Results: POAF occurred more frequently in patients with prior asymptomatic SARS-CoV-2 infection than in those without documented infection (8/34, 23.5% vs 1/30, 3.3%; two-sided Fisher’s exact p = 0.029). The absolute risk difference was 20.2 percentage points. The unadjusted odds ratio was 8.92 (95% CI, 1.04 – 76.24), and the relative risk was 7.06 (95% CI, 0.94 – 53.22). Confidence intervals were wide, and the relative-risk interval included the null. All POAF episodes in the prior-infection group occurred within 24 postoperative hours. At discharge, 4 of 8 patients had returned to sinus rhythm; 4 had rate-controlled atrial fibrillation and received a non – vitamin K antagonist oral anticoagulant for 3 months. One patient was readmitted with AF within 10 days.

Conclusion: POAF was more frequent among patients with documented prior asymptomatic SARS-CoV-2 infection, but the small event count and wide confidence intervals preclude a definitive estimate of risk. These hypothesis-generating findings require confirmation in larger prospective studies with standardized rhythm monitoring.