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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

Background There is conflicting evidence regarding the use of statins to reduce the risk of post-operative atrial fibrillation (POAF) in patients undergoing cardiac surgery. Purpose We sought to determine the effects of statin use on the burden of new-onset post-discharge POAF in the Post-Surgical Enhanced Monitoring for Cardiac Arrhythmias and Atrial Fibrillation (SEARCH-AF) CardioLink-1 randomized controlled 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 endpoint was the occurrence of cumulative atrial fibrillation/flutter (AF/AFL) lasting for ≥6 minutes detected by continuous monitoring or AF/AFL documented by a 12-lead electrocardiogram within 30 days of randomization. Using time-to-event analysis and Cox regression, we evaluated the association between the risk of post-operative AF in relation to statin use and dosing intensity (low, moderate, high) at the time of discharge. We excluded patients who experienced post-operative AF during hospitalization in this analysis. Results In the overall cohort (n=336), 260 (77.4%) patients were treated with statins at the time of hospital discharge. There were 18 (5.4%) patients who experienced post-operative AF during hospitalization. Patients prescribed with statins were more likely to be male (p=0.018), had lower CHA2DS2-VASc scores (p=0.011), and were more likely to undergo isolated coronary artery bypass grafting (CABG) (p=0.083). Baseline characteristics were otherwise similar between the 2 groups. Patients treated with statins at discharge had a 2-fold lower rate of post-operative AF than those who were not treated with statins in the overall cohort (17.6% vs. 8.2%, Log-Rank p=0.017) and among those who were randomized to continuous cardiac rhythm monitoring (31.6% vs. 16.0%, Log-Rank p=0.027) (Figure). After adjusting for surgery type (CABG vs. valve surgery) and the CHA2DS2-VASc score, statin use at discharge was associated with a lower risk of post-operative AF within 30 days after surgery (hazard ratio 0.48, 95% CI 0.24–0.97). Furthermore, increasing intensity of statin therapy was associated with lower risk of POAF (ptrend=0.0012) (Figure 1) Conclusion Among cardiac surgery patients with risk factors for stroke and no history of pre-operative AF, the use of statins was associated with a reduction in post-operative AF risk within 30 days of discharge. The routine use of high-intensity statin to prevent post-operative AF after cardiac surgery deserves further study. Funding Acknowledgement Type of funding sources: Other. Main funding source(s): Heart and Stroke Foundation of Canada

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