Longer paroxysmal postoperative atrial fibrillation correlates with higher recurrence of atrial fibrillation in patients with heart failure with reduced ejection fraction

Background: Postoperative atrial fibrillation (POAF) is a common arrhythmia after cardiac surgery. Heart failure is a known risk factor for developing atrial fibrillation. Little is known about the long-term prognosis and incidence of recurrent atrial fibrillation. This study aims to examine whether longer postoperative atrial fibrillation correlates with an increased incidence of recurrent atrial fibrillation among patients with heart failure during the follow-up period. Methods: From January 2020 to December 2023, 2.419 cardiac surgeries were performed at the Zan Mitrev Clinic, Skopje, R. Macedonia. We examined the patients who developed postoperative atrial fibrillation and were discharged in sinus rhythm. We excluded patients with permanent atrial fibrillation and those lost in the follow-up from the study. Echocardiography was performed before the surgery and at every cardiology appointment after discharge (after 1 week, 3 weeks, 2 months, then every 6 months). The atrial fibrillations were subdivided into two groups, i.e., shorter or longer than 48 hours. The heart failure was classified according to the 2021 ESC guidelines for heart failure. We followed up with all patients until December 2024. We retrospectively collected the data from the Hospital Information System. We used the Fisher exact test for statistical analyses. Results: A total of 379 patients (16%) had postoperative atrial fibrillation, out of which 315 (83%) had atrial fibrillation for the first time in their life, and 64 (17%) patients had previous paroxysmal atrial fibrillation. These patients were followed for a mean of 22±12 months period. Ninety-three patients (25%) had heart failure with a reduced ejection fraction, 188 (50%) had heart failure with a mildly reduced ejection fraction, and 20% had an ejection fraction above 50%. One hundred ninety-three patients (51%) had atrial fibrillation shorter than 48 hours, while 185 patients (49%) had POAF longer than 48 hours. Patients with heart failure with a reduced ejection fraction and POAF longer than 48 hours had a statistically higher incidence of recurrent atrial fibrillation in the follow-up period (p < 0.028). There was no statistical difference between the recurrence of atrial fibrillation and the length of POAF in the group of patients with a mildly reduced ejection fraction (p=0.359) and those with normal ejection fraction. Conclusion(s): Recurrent atrial fibrillation during the follow-up period occurs more frequently only in patients with heart failure with reduced ejection fraction and postoperative atrial fibrillation longer than 48 hours.