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Study Summary

SEARCH-AF was a parallel, open-label, randomized trial that sought to determine whether continuous monitoring resulted in higher rates of detection of atrial fibrillation (AF) or atrial flutter (AFL) during the post-discharge period after cardiac surgery. Patients were randomized to rhythm monitoring (N = 136, continuous cardiac rhythm monitoring within the first 30 days after randomization) or usual care (N = 173, no protocol-mandated monitoring at discretion of treating physician). Patients were included if they were in sinus rhythm, underwent coronary artery bypass grafting (CABG) or valve repair/replacement ± CABG, no plan for oral anticoagulation, and had a CHA2DS2-VASc score ≥4 or ≥2 with at least one of the following: chronic obstructive pulmonary disease, sleep apnea, estimated glomerular filtration rate <60 ml/min/1.73m2, ≥mild left atrial dilatation, or body mass index ≥30 kg/m2. Patients were excluded if they had a history of AF/AFL, had AF/AFL ≥14 hours postoperatively, mechanical heart valve, hospitalization ≥10 days, or received ≥5g of amiodarone. The primary outcome — incidence of AF/AFL duration ≥6 minutes or documentation of AF/AFL by 12-lead electrocardiogram within the first 30 days — was observed in 19.6% of the enhanced monitoring group compared with 1.7% of the usual care group (P <0.001; see accompanying Hurst’s Central Illustration). Of those with AF/AFL detected with enhanced monitoring, 8.6% (14 patients) had cumulative AF/AFL≥ 6 hours and 3.1% (5 patients) had cumulative AF/AFL ≥ 24 hours. Prescription of oral anticoagulation within the first 45 days did not differ between groups (4.3% versus 2.3%, rate difference 2%, 95% CI -1.9% to 5.8%).


Study Strengths: The trial was randomized and included a patient population most likely to benefit from a change in practice: initiating anticoagulation. The results demonstrate that approximately one in five patients develop AF/AFL after cardiac surgery, identifying a patient population that will inform future studies. This trial also focused attention on inconsistent clinical practice in that prescription of anticoagulation did not differ between groups at 45 days, despite one-fifth of patients in the monitoring group demonstrating AF/AFL at 30 days of follow-up, compared with 1.7% in the usual care group.

Study Limitations: Although monitoring was repeated at 6 months, the primary end point was limited to 30 days, potentially underestimating the long-term risk of postoperative AF/AFL. Patients with a prolonged hospitalization were excluded, precluding identification in this also potentially higher risk population. The study was underpowered to detect differences in stroke risk. Furthermore, 10.4% of patients in each group had a history of either stroke or transient ischemic attack with unclear etiology. Also unknown is whether the detection of postoperative AF is attributable to surgery in those patients or whether enhanced monitoring demonstrated paroxysmal AF that had gone undiagnosed.

Next Steps/Clinical Perspective: This trial highlights the need for further adequately powered studies to describe the incidence of AF/AFL in a larger patient population in the context of hard outcomes such as mortality, myocardial infarction, and stroke. Given the discrepancy between identification of incident AF and prescription of anticoagulants, further studies will need to assess if the use of anticoagulation in such patients meaningfully modulates patient risk. The culmination of these works will likely inform guideline recommendations for monitoring and treatment after cardiac surgery.

Trial Reference

Enhanced monitoring for atrial fibrillation following cardiac surgery: primary results of the SEARCH-AF CardioLink trial. Presented by Dr. Subodh Verma at the AHA Scientific Sessions, November 16, 2020

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