Postoperative atrial fibrillation burden and progression patterns after cardiac surgery during 2.5 years of continuous rhythm monitoring
Authors: Kawczynski M , Gilbers M D , Zeemering S , Isaacs A , Maessen J G , Verheule S , Bidar E , Schotten U 
Published: May 2024

Abstract

Background
Early postoperative atrial fibrillation (POAF) is a frequent complication after cardiac surgery, with an incidence of up to 50%.(1, 2) The clinical presentation of early-POAF, however, might be highly diverse, showing great individual differences in symptoms, as well as POAF-specific characteristics such as the number of episodes, duration of episodes, and the percentage of time spent in POAF (POAF-burden). It is currently unknown how these early-POAF characteristics, particularly POAF-burden, are related to the risk of developing late-POAF recurrences.

Purpose
To establish the association between early-POAF characteristics, in particular POAF-burden, and late-POAF occurrence and burden.

Methods
Patients with and without a history of AF undergoing cardiac surgery were included. Preoperatively, all patients underwent echocardiography, electrocardiography, and blood biomarker analysis. Intraoperatively, all patients received an implantable loop recorder for a period of 2.5 years. POAF was defined as an AF episode lasting at least 2 minutes, detected by the ILR algorithm, and all episodes were manually checked by the investigators. POAF-burden was calculated as the percentage of time in AF for different time intervals (early: 0-3 months, late: 3-30 months). Classification of burden was performed based on cut-off values for tertiles. Also, associations between early-POAF characteristics, such as episode duration, and the incidence of late-POAF were analyzed.

Results
The study population consisted of 98 patients undergoing cardiac surgery (71 without preoperative AF history and 27 with preoperative AF history), out of which 53 developed POAF. Early-POAF occurred in 46 patients, and late-POAF in 36 patients. Early-POAF was associated with an increased occurrence of late POAF after adjusting for age, sex, PAF-history, and persistent AF-history (adjusted hazard ratio [aHR] = 4.62, 95% CI: 1.93-11.05, p&lt;0.001) (Figure 1A). Multiple regression analysis, adjusted for age, sex, PAF-history, and persistent AF-history, revealed a gradual increase in late-POAF hazard between the early-POAF burden tertiles compared to patients without early-POAF (p&lt;0.001) (Figure 1B). Similarly, the longest individual early-POAF episode and the number of early-POAF episodes were both associated with an increased late-POAF hazard (p&lt;0.001 and p&lt;0.001, respectively) (Figure 1C-D). The highest POAF-burden was observed in the early postoperative phase, with a significant reduction in the late phase (p=0.007) (Figure 2A). Overall, 84 patients had no late-POAF or a reduction in POAF burden, while 14 patients showed an increase in POAF-burden compared to the early postoperative phase (Figure 2B).

Conclusion
Early-POAF characteristics, such as POAF-burden, are strongly associated with an increased occurrence of late-POAF. The highest POAF-burden is present in the early postoperative phase, and only a minority of patients experience an increase in late-POAF burden.Figure 1Figure 2