Characteristics of patients with cryptogenic stroke and atrial fibrillation detected using insertable cardiac monitoring in the chronic phase: a subanalysis of the LOOK study.

Introduction: Occult atrial fibrillation (AF) is a major underlying cause of cryptogenic stroke (CS) and is frequently identified only after hospital discharge. However, the characteristics of late-detected AF remain unclear. In this study, we aimed to investigate the clinical characteristics of patients with late-detected AF identified >30 days after the onset of stroke, compared with those without AF detection. Methods: Data from patients with CS who underwent implantation of an insertable cardiac monitor in the multicenter LOOK study were analyzed. Patients were categorized into three groups. Early-detected (within 30 days), Late-detected (after 30 days), and No-detected AF. Clinical characteristics were primarily compared between the Late-detected and No-detected AF groups, with additional exploratory comparisons involving the Early-detected AF group. Results: AF was detected in 42 (32.8%) of the 128 patients (median age, 71 years; 68.0% male). Eight patients were classified into the Early-detected AF group, 34 into the Late-detected AF group, and 86 into the No-detected AF group. Compared with the no-detected AF group, patients in the late-detected AF group were older (78 vs. 66 years, Discussion: Patients with CS and late-detected AF, compared with those without AF detection, were older, had fewer atherosclerotic risk factors, and more frequently had large-vessel occlusion. These findings highlight the importance of long-term rhythm monitoring after stroke in patients at higher risk of late-detected AF.