Treatment of Cryptogenic Stroke Patients with Atrial Fibrillation Detected by Insertable Cardiac Monitors Reduces Recurrent Stroke Risk to Background Levels

Atrial fibrillation (AF) is a known risk factor of ischemic stroke with a reported fivefold increase in incidence. However, it is not well established whether treatment with oral anticoagulation (OAC) in cryptogenic stroke patients with AF, detected by insertable cardiac monitors (ICMs), reduces the risk of recurrent stroke. We aimed to compare recurrent stroke rates between cryptogenic stroke patients who have AF detected by ICMs and thus started on OAC treatment and those without detected AF. We performed a combined retrospective and prospective analysis of consecutive patients who received an ICM indicated for cryptogenic stroke and were followed up with between July 2015 and November 2019. Patients with a prior documented history of AF were excluded. All patients were required to have a home remote monitoring system. We calculated the rates of AF detection and OAC initiation, then compared recurrent annualized stroke rates (ASRs) between patients with and without AF detected. A total of 298 patients with ICMs were included in the study [mean ± standard deviation age: 77 ± 11.7 years; female/male: 147/151; virtual CHA(2)DS(2)-VASc score: 4.96 ± 1.28 points]. AF was discovered in 91 patients (~30%) over a mean 19.3 months follow-up. Of those, 65 (71.4%) were started on OAC, 12 (13.2%) were already on OAC, and 10 (11%) remained non-anticoagulated. In four (4.4%) patients, OAC was started after recurrent stroke when AF was diagnosed. A total of 24 of 298 patients developed recurrent strokes (ASR: 5.0%). Among the 24 patients with recurrent strokes, four had new AF and were on OAC (ASR: 3.23%), six had new AF and were not anticoagulated (ASR: 26.62%), and 14 had no AF detected and no OAC (ASR: 4.20%). Our study found new AF detected by ICMs in almost one-third (30%) of cryptogenic stroke patients (consistent with previous studies), and the majority of them (89%) received OACs. There was no significant difference in the recurrent stroke rate among patients without AF detected and those with AF detected and on OAC. Rigorous arrhythmia monitoring using ICMs can increase new AF detection rates in cryptogenic stroke patients, thereby allowing early initiation of OACs, ultimately reducing the risk of recurrent stroke to background levels.