AFOTS - Medical Illness Cases for Atrial Fibrillation (AFOTS Trial)

Rationale Atrial fibrillation (AF) often occurs transiently in the setting of an acute stressor (e.g. medical illness or surgery). Uncertainty exists as to whether AF Occurring Transiently with Stress (AFOTS) is secondary to a reversible precipitant and is benign, or is a first presentation of paroxysmal AF and associated with a risk of stroke. AFOTS is a common occurrence (\>40% in some intensive care settings), but there is a lack of evidence to guide its management and guidelines have called for further research in this area. Retrospective data suggest that many patients with AFOTS (\>50%) will experience recurrent AF. These estimates were obtained without using sensitive methods for AF detection, which raises the possibility that the true rate of recurrent AF is much higher. As the rate of recurrent AF increases, it becomes increasingly likely that AFOTS is just the first detection of typical "clinical" AF. Objective To use a sensitive strategy to determine the rate of recurrent AF among patients who experienced AFOTS following i) non-cardiac surgery OR ii) medical illness, compared to matched controls. Methods Two multi-centre, 138-patient, observational cohorts. AFOTS patients will have new AF, documented by 12-Lead ECG or surface monitoring, during hospitalization for non- cardiac surgery (Cohort 1) or medical illness (Cohort 2). Controls will be patients without a history of AF who are matched for age (within 5 years), sex and exposure to stressor. Participants will wear a 14-day ECG monitor at 1 and 6 months after discharge. The endpoint is detection of AF. Impact If the incidence of AF after AFOTS is \>80%, clinicians could be advised to treat AFOTS like "clinical" AF and initiate anticoagulation according to guidelines. Otherwise, a strategy of surveillance for AF would be advised. Hypothesis 1. Patients who experience AFOTS will have a higher future incidence of AF and of stroke compared to patients exposed to a similar stressor but who did not develop AF. 2. The risk of recurrent AF after AFOTS will be sufficiently high (\> 80%) to warrant routine initiation of long-term OAC in all cases.