Determinants and impact of postoperative atrial fibrillation burden during 2.5 years of continuous rhythm monitoring after cardiac surgery

BACKGROUND: Early postoperative AF (POAF) is common after cardiac surgery and is associated with late-POAF recurrences. However, little is known about the burden of POAF, and its potential impact on long-term outcomes after cardiac surgery, particularly on the risk for late-POAF recurrences. OBJECTIVE: To establish the distribution of POAF burden and to determine the association between early-POAF burden and late-POAF recurrences during 2.5 years of continuous rhythm monitoring after cardiac surgery in patients with and without preoperative history of AF. METHODS: Patients undergoing cardiac surgery were prospectively enrolled and postoperatively continuously monitored with an implantable loop recorder (ILR) for 2.5 years. All patients underwent extensive clinical assessment at baseline. During the follow-up all AF episodes were registered, and AF-associated metrics, such as burden, were calculated for different time intervals. Early-POAF was defined as AF within first 90 postoperative days and late-POAF as AF after this interval. RESULTS: A total of 98 consecutive patients were included. POAF burden during the early postoperative phase was significantly higher as compared to the late postoperative phase (p<0.001). The longest individual POAF episode was strongly associated with increased POAF burden after adjusting for age, sex, and AF-history (standardized Beta: 0.91, p<0.001). Also, early-POAF burden was associated with late-POAF (re)occurrence after adjusting for age, sex, AF-history (adjusted Hazard Ratio=1.93, 95%CI: 1.42-2.62, p<0.001). CONCLUSION: POAF burden was significantly associated with the longest individual POAF episode duration. Additionally, greater early-POAF burden was associated with increased late-POAF incidence, highlighting its potential in estimating the risk for long-term POAF recurrences.