High Detection Rate of Atrial Fibrillation With Insertable Cardiac Monitor Implantation in Patients With Cryptogenic Stroke Diagnosed by Magnetic Resonance Imaging.

Background: Detection and treatment of atrial fibrillation (AF) is a major goal in preventing secondary stroke. Insertable cardiac monitors (ICMs) are available for diagnosis of arrhythmia monitoring in patients with cryptogenic stroke. Magnetic resonance imaging (MRI)-based diagnostic evaluation for acute ischemic stroke subtype classification is common in Japan and can be useful for specific diagnosis of cryptogenic stroke. Purpose: We aimed to investigate the detection rate of AF with an ICM in patients with cryptogenic stroke who were diagnosed by MRI. Methods: We performed a retrospective, multicenter, observational study. AF monitoring data of an ICM (Reveal LINQ) in patients with cryptogenic stroke were registered from 5 stroke centers in Japan between October 2016 and March 2018. ICM candidates in cryptogenic stroke were diagnosed by MRI-based evaluation and selected according to the criteria proposed by the Japan Stroke Society. Detection of AF was defined as AF for longer than 120 seconds. Results: Eighty-four consecutive patients (64 men; aged 38-90 years) underwent ICM implantation after diagnosis of cryptogenic stroke. AF was detected in 22 of 84 (26.2%) patients with an ICM during a median follow-up of 221.5 days (range: 93-365 days). The detection rate of AF within 3 months after ICM implantation was 21.4%. Conclusions: The AF detection rate with an ICM is approximately one fifth within 3 months in patients with cryptogenic stroke as diagnosed by MRI. Our data suggest that the Japanese criteria based on MRI may be useful for selecting adequate candidates for ICM implantation.