Long-term recurrence of new-onset post-operative AF in cardiac surgery patients as detected by an implantable loop recorder: a systematic review and individual participant data meta-analysis
Authors: Kaur H , Healey J S , Belley-Cote E P , Bidar E , Kawczynski M , Ayala-Paredes F A , Ayala-Valani L , Sandgren E , El-Chami M F , Jorgensen T H , Thyregod H G H , Sabbag A , Mcintyre W F 
Published: November 2023

Abstract

Introduction
New-onset atrial fibrillation (AF) occurs in 25-50% of patients after cardiac surgery. For some patients, post-operative AF (POAF) is thought to be a transient entity, while in others it represents a first presentation of paroxysmal or persistent AF. The long-term rate of AF recurrence in patients with POAF is not well defined.

Objective
To estimate the recurrence of AF in patients who had new-onset POAF following cardiac surgery as evaluated with an implantable loop recorder (ILR).

Methods
We searched MEDLINE, Embase and Cochrane CENTRAL to August 18, 2022 for studies of adult patients without a history of AF, who had POAF detected following cardiac surgery and received an ILR. We defined AF occurring in the first 30 days after surgery as POAF. We defined AF occurring beyond 30 days after surgery as AF recurrence.
We contacted authors of eligible studies with a request to contribute individual participant time-to-event data on AF recurrence and participant demographics at the study level. When individual data were not available, we estimated events from figures in published study records. We constructed a Kaplan-Meier curve illustrating the time to first AF recurrence, with 95% confidence intervals (CIs).

Results
From 8111 screened records, we identified 8 eligible studies (Table 1). All studies were single-centre cohorts from 7 countries including the United States of America (2), Canada, Denmark, Israel, The Netherlands, Russia and Sweden. Two studies defined AF recurrence as lasting 30 seconds, four defined AF recurrence as lasting at least 2 minutes, one defined AF recurrence as lasting at least 5 minutes and one defined AF recurrence as lasting at least 6 minutes. We received data for 6 studies and estimated events for one study; data were not available from one study. We pooled data from a total of 186 participants, with a median follow-up of 1.7 (interquartile range (IQR): 1.3 – 2.8) years. Overall, 19.7% of participants were female, 79.8% of participants had isolated CABG, and the median (IQR) CHA2DS2-VASc was 3 (1 – 6).
Rates of AF recurrence beginning after the 30-day post-operative period were: 15.1% (95% CI 10.5% – 21.2%) at 3 months, 23.9% (95% CI 18.1% – 31.0%) at 6 months, 30.7% (95% CI 24.1% – 38.1%) at 12 months and 39.2% (95% CI 32.0% – 47.0%) at 18 months (Figure 1, wherein the shaded area indicates the 95% CI).

Conclusions
For patients with new-onset POAF following cardiac surgery, AF recurrence, as detected by an ILR, is common, with approximately 1 in 3 experiencing recurrence in the first year after surgery. The optimal strategy for monitoring for AF recurrence and its clinical sequelae in this population remains uncertain.Figure 1:Incidence of AF RecurrenceTable 1:Study Characteristics Table