Post-operative atrial fibrillation: not just a transient phenomenon

Abstract

Abstract Funding Acknowledgements Type of funding sources: None. Background A high proportion of patients undergoing cardiac surgery develop atrial fibrillation (AF) in the immediate post-operative period. To assess whether this translates into long-term AF, studies have used incidence of stroke as a surrogate marker, however the rhythm has not been directly measured. Our study retrospectively reviewed device checks of patients with permanent cardiac devices who underwent cardiac surgery in order to directly measure AF up to 18 months post cardiac surgery. Purpose To assess whether the development AF in the immediate post-operative period relates to the prevalence of longer-term AF after cardiac surgery. Methods Patients who had undergone a coronary artery bypass graft (CABG) or valve surgery between January 2011 and March 2020 and who had a pre-existing device or a device inserted within 1 year after surgery were identified. Patients were excluded if they had a congenital cardiac condition or a diagnosis of AF pre-operatively. Patients were categorised as having AF in the immediate post-operative period if AF was coded in the electronic ICU observation chart, mentioned on the discharge summary, or found in a device check <6 weeks post-surgery. Device checks were analysed up to 18 months post-surgery and AF was confirmed if lasting >6 minutes and documented on atrial electrogram (EGM). Comorbidities and operation details were gathered from institutional surgical database and medical notes. Results 359 patients at our institution met initial criteria. 94 had device checks available and were used for final analysis. Mean follow up duration was 377 days. In total 41 (44%) patients developed AF in the immediate post-operative period. Patients developing post-op AF were older (69 vs. 64 years old, p=0.01) and had a different spread in operation type (CABG only 27% vs. 28%, valve only 51% vs. 68%, combined CABG & valve 22% vs. 4%, p=0.02) but there was no difference in other relevant characteristics (see Table 1). In total, 24 (26%) patients developed longer term AF, with significantly higher proportion in those who developed immediate post-operative AF (see Figure 1). Immediate post-operative AF and hypertension demonstrated a significant association with longer-term AF on univariate regression analysis using a significance value of 0.1. On multivariate analysis only immediate post-operative AF remained significant (odds ratio 3.75 (95% confidence interval 1.38-10.22), p=0.01). Conclusion Developing AF in the post-operative period appears to be an independent predictor of developing clinically significant AF up to 18 months after surgery. This is an important finding in identifying patients who may be at higher risk of thromboembolic events. Further research is required to determine the optimal approach, in particular consideration of anticoagulation in this patient group.