Valvular surgery is associated with an increased risk of post-operative atrial fibrillation: secondary analysis of the SEARCH-AF CardioLink-1 randomized trial

Abstract Background Patients undergoing valve surgery have a higher risk of developing post-operative atrial fibrillation (POAF) relative to those undergoing isolated coronary artery bypass grafting (CABG). Whether this risk extends beyond hospital discharge is unknown. Purpose We examined the association between surgery type (isolated CABG vs. valve repair/replacement) on the incidence of post-operative atrial fibrillation (POAF) by conducting a secondary analysis of the Post-Surgical Enhanced Monitoring for Cardiac Arrhythmias and Atrial Fibrillation (SEARCH-AF) CardioLink-1 randomized trial. Methods In the SEARCH-AF trial, 336 patients with risk factors for stroke (CHA2DS2-VASc score ≥2) and no history of preoperative AF were randomized to usual care or continuous cardiac rhythm monitoring for 30 days after discharge from cardiac surgery with a wearable, patched-based device. The primary outcome was occurrence of cumulative atrial fibrillation/flutter (AF/AFL) lasting for ≥6 minutes detected by continuous monitoring or AF/AFL documented by a 12-lead ECG within 30 days of randomization. We compared the risk of POAF between patients who underwent CABG vs. valve repair/replacement. Patients who experienced post-operative AF during hospitalization were excluded from this analysis. Results The overall cohort consisted of 255, 39, and 42 patients who underwent isolated CABG, isolated valve replacement/repair, and CABG + valve repair/replacement, respectively. Baseline characteristics were similar among the groups except for younger age (p=0.0014), higher prevalence of preoperative myocardial infarction (p=0.002) and lower ejection fraction (p=0.025) in the isolated CABG group. Eighteen patients experienced post-operative AF during hospitalization. Patients who underwent CABG + valve surgery or isolated valve surgery were more likely to experience post-operative AF compared with those who underwent isolated CABG (Log-Rank ptrend=0.0096). Among patients who were randomized to continuous cardiac rhythm monitoring, the probability of post-operative AF among patients who underwent isolated CABG, valve surgery, and CABG + valve surgery was 15.8%, 29.4%, and 35.0%, respectively (Log-Rank ptrend=0.017). After multivariable adjustment, the risk of developing post-operative AF within 30 days after discharge remained higher among patients who underwent valve surgery compared with those who underwent isolated CABG (hazard ratio (HR) 2.22, 95% CI 1.01–4.87. Patients who underwent CABG + repair/replacement had the highest risk of experiencing post-operative AF when compared to patients who underwent isolated CABG (HR 2.78, 95% CI 1.12–6.86). Conclusion Patients undergoing valve repair or bioprosthetic valve replacement have a substantial risk of post-operative AF within 30 days after discharge from surgery. An aggressive cardiac rhythm monitoring strategy during this vulnerable period should be considered for this high-risk patient population. Funding Acknowledgement Type of funding sources: Other. Main funding source(s): Heart and Stroke Foundation of Canada