Embolic Stroke of Undetermined Source: Role of Implantable Loop Recorder in Secondary Prevention

Background and Aims: Atrial fibrillation (AF) is the most important cause of embolic stroke of undetermined source (ESUS). Implantable loop recorder (ILR) demonstrated the highest sensitivity for detecting it. This register was created to confirm the high prevalence of AF in patients after ESUS and to verify possible benefits on clinical outcomes such as TIA (Transient Ischaemic Attack)/stroke recurrence and death using ILR. Methods: A total of 278 patients admitted to "Molinette" Hospital in Stroke Unit department between 2011 and 2016, diagnosed with ESUS, underwent ILR implantation if they had at least one risk factor for AF. A total of 165 patients admitted to other departments in the same center for the same pathology, without ILR, represent the control group. We used propensity score to select 132 patients from each group (matching age, sex, CHADS-VASC, and HAS-BLEED baseline characteristics). Results: The detection rate of AF episodes was significantly higher in the ILR group (p < 0.001). No significant protective role of ILR for clinical endpoints was found on univariate analysis, although a trend towards significance has been pointed for the composite outcome of death and ischemic events recurrence (OR 0.52, CI 0.26-1.04, p = 0.06). A protective role of ILR was found for deaths (OR 0.4, CI 0.17-0.94, p 0.03) and for the composite outcome (OR 0.41, CI 0.19-0.87, p 0.02) on multivariate analysis in the best subsets. Conclusion: With our statistical models, we identified a significant clinical benefit from ILR monitoring, evidenced by a trend of less death and TIA/stroke recurrence and relevant ILR protection for prediction of TIA/stroke recurrence.