Meta-Analysis of Randomized Clinical Trials Comparing the Impact of Implantable Loop Recorder Versus Usual Care After Ischemic Stroke for Detection of Atrial Fibrillation and Stroke Risk

Abstract

Implantable loop recorder (ILR) is recommended to detect subclinical atrial fibrillation (AF) after cryptogenic stroke; however, the clinical outcomes of this practice is unclear. We conducted a systematic review and meta-analysis of randomized controlled trials to evaluate 12-month AF detection, change in oral anticoagulation (OAC), and recurrent stroke in ILR versus usual care after ischemic stroke. We searched Medline, Embase, Web of Science, Cochrane Library for randomized controlled trials comparing ILR with usual care after any ischemic stroke. Primary outcomes were cumulative AF detection and recurrent stroke (ischemic or hemorrhagic) or transient ischemic attack over 12 months. Secondary outcome was OAC initiation. Meta-analysis was performed with Mantel-Haenszel pooled odds ratios (ORs) and random effects models. Of 200 identified articles, 3 trials were included (1,233 participants). Cryptogenic stroke and underlying AF included cryptogenic stroke only, stroke of known cause and underlying-AF included small or large vessel stroke only, and post embolic rhythm detection with implantable vs external monitoring included all ischemic strokes. The 12-month AF detection was 13% in the ILR group and 2.4% in controls. ILR was more likely to detect AF compared with usual care (OR 5.8, 95% confidence interval 3.2 to 10.2). Stroke or transient ischemic attack occurred in 7% with ILR and 9% with usual care (OR 0.8, 95% confidence interval 0.5 to 1.2). In patients with detected AF, 97% and 100% were started on OAC in cryptogenic stroke and underlying AF and post embolic rhythm detection with implantable vs external monitoring, respectively, compared with 68% in stroke of known cause and underlying-AF. In conclusion, ILR was superior to usual care in AF detection, but the relative low incidence of AF and the nondifferential risk of stroke between the ILR and usual care arms may suggest that most patients do not benefit from ILR implantation. Further studies are warranted to understand if patient selection can be improved to increase the diagnostic yield of ILR.