Multicenter Observational Study on Detection of Atrial Fibrillation Using Insertable Cardiac Monitors in Patients With Cryptogenic Stroke in Japan : LOOK Registry - Study Design and Characteristics

Abstract

Background Paroxysmal atrial fibrillation (AF) is a probable cause of cryptogenic stroke (CS) and AF detection and treatment are important for secondary prevention of stroke. Insertable cardiac monitors (ICMs) are clinically effective in screening for AF and superior to conventional CS follow-up. However, available data are primarily derived from small retrospective studies within Asian cohorts and there is a lack of detailed analyses of differences in patients with and without AF. In this study, we aim to identify the incidence of AF detection and risk stratification criteria within the LOOK (multicenter observational study on detection of atrial fibrillation using insertabLe cardiac mOnitors in patients with cryptOgenic stroKe) registry. Results may benefit patients with CS by enabling clinical practitioners to better predict occult AF and stroke via ICMs. Methods The LOOK registry is a multicenter, prospective, observational study evaluating the proportion, timing, and characteristics of AF detection in patients diagnosed with CS via ICMs. Patient enrolment in this ongoing study started in February 2020 with a target of 200 patients. We are investigating first detection of AF (lasting > 2 minutes) during follow-up at 6, 12, and 24 months via ICM implantation. Patient characteristics, medical history, serum biomarkers, magnetic resonance neuroimaging, atrial cardiomyopathy markers, electrocardiogram readings (including 24-hour Holter electrocardiogram readings), transesophageal echocardiography, cognitive status, stroke recurrence, and functional outcomes are compared between patients with and without AF in this study. Discussion This prospective, multicenter study aims to identify the current status of AF detection in CS patients in Japan. The findings of this study will help identify AF markers and generate a risk scoring system with a novel and superior screening algorithm for occult AF detection, while identifying candidates for ICM implantation and informing the development of diagnostic criteria for CS. Trial registration: UMIN000039809; Registered on 13 Mar 2020