New onset, recurrence and progression of atrial fibrillation 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 2023

Abstract

Funding Acknowledgements
Type of funding sources: Public grant(s) – National budget only. Main funding source(s): This study was supported by the Netherlands Heart Foundation (CVON2014-09, RACE V: Reappraisal of Atrial fibrillation: interaction between hyperCoagulability, Electrical remodelling, and Vascular destabilisation in the progression of AF).

Background
Atrial fibrillation (AF) in the early postoperative phase (POAF) is a frequent complication after cardiac surgery with an incidence of up to 50%. Recent studies have shown that early-POAF is a one of the strongest predictors of late recurrences. However, it is unknown how POAF-burden (percentage of time in AF) progresses in the months and years following surgery. Recent studies suggested that AF-burden is associated with increased risk of stroke and therefore identifying factors associated with a higher POAF-burden is desirable.

Purpose
To investigate AF-burden progression patterns and factors associated with increased AF-burden after cardiac surgery during 2.5 years of continuous rhythm monitoring.

Methods
Patients with and without history of AF undergoing cardiac surgery were included. Preoperatively, all patients underwent transthoracic echocardiography, electrocardiography, and blood biomarker analysis. Intraoperatively, all patients received an implantable loop recorder. Continuous rhythm monitoring was performed over a period of 2.5 years. AF-burden progression was calculated as percentage of time in AF for different time intervals (0-3, 3-12, and 12-30 months) and presented in alluvial-plots. Classification of burden was performed based on the cut-off values for tertiles. In addition, AF-characteristics such as episode duration and ventricular rate were analyzed as potential surrogate markers of AF-burden.

Results
The study population consisted of 134 patients undergoing cardiac surgery. Median follow-up (FU) was 2.7 years (IQR: 2.2-2.9 years) and 98 patients completed 2.5 years of FU. Eighty-one (60.4%) patients developed AF during the follow-up period. Early-POAF (first 3 months) occurred in 75 patients (56.0%) and late-POAF (after first 3 postoperative moths) in 47 patients (35.1%). Highest AF-burden was observed in the first 3 postoperative months with a significant reduction between 3-12 moths (p=0.007) (Figure 1). In the period between 12-30 months an increase in AF burden was observed for all groups (p&lt;0.001), however the burden remained lower as compared to the first 3 postoperative months (Figure 1). Overall, 50% of patients showed a reduction of AF burden and only 11% an overall increase. Individual postoperative AF-burden was strongly associated with the longest AF-episode (Spearman’s rho=0.86, 95%CI: 0.75-0.92, p&lt;0.001) (Figure 2A), and to a lower extent with the duration of the median episode (Spearman’s rho=0.38, 95%CI: 0.13-0.58, p=0.001) (Figure 2B).

Conclusion
POAF is a frequent complication in the early and late postoperative phase with the highest AF-burden present in the first 3 postoperative months. Also, AF-burden seems to be highly correlated to the longest individual episode duration.