492 embolic stroke of undetermined source: role of implantable loop recorder in asymptomatic atrial fibrillation detection and secondary prevention of new embolic events

Abstract Background and Aims AF (Atrial Fibrillation) is the most important cause of Embolic Stroke of Undetermined Source (ESUS). Implantable Loop Recorder (ILR) demonstrated the highest sensitivity for detecting post-stroke asymptomatic AF. This register was created to assess the prevalence of AF episodes in patients after ESUS and to verify possible benefits on clinical outcomes such as TIA or stroke recurrence and death using ILR. Methods 278 patients admitted to the Stroke Unit of “Città della Salute e della Scienza” hospital in Torino between 2011 and 2019, underwent ILR implantation if they had at least one risk factor for AF including obesity, hyperthyroidism, atrial enlargement at transthoracic echocardiography, severe mitral valve disease, CHADS-VASc score ≥ 4, age > 70 years old and diabetes. The control group was composed of 165 patients admitted in other departments of the same hospital diagnosed with ESUS, not implanted with ILR. We used propensity score matching to select 132 patients from each group (matching age, sex, CHADS-VASc, and HAS-BLED baseline characteristics). Risk and protective factors were estimated for clinical outcomes (deaths and TIA or stroke recurrence) and were evaluated with logistic regression univariate and multivariate analyses. Results The detection rate of AF episodes longer than 5 minutes was significantly higher in the ILR group (41.7% vs 15.9%, p<0.001). On univariate analysis, we found a trend towards a protective role of ILR for the composite outcome of TIA or stroke recurrence and mortality (OR 0.52, CI 0.26–1.04, p 0.06). On multivariate analysis, we found a protective role of ILR in terms of deaths (OR 0.4, CI 0.17–0.94, p 0.03) and for the composite outcome of ischemic event recurrences and deaths (OR 0.41, CI 0.19–0.87, p 0.02). Age was consistently identified as a risk factor for all the clinical outcomes. Conclusion In patients with ESUS and at least one risk factor for AF, episodes of AF longer than 5 minutes are identified in 41.7% of the cases thanks to ILR. Our study demonstrated that a policy including ILR in patients with ESUS also gives a clinical benefit in terms of TIA or stroke recurrence and death, although limited size of the population and possible presence of selection bias may limit the generalisation of our results.