Value of implantable loop recorders in detecting atrial fibrillation for stroke prevention: a systematic review and meta-analysis

Background Though undiagnosed in many patients, especially those with cryptogenic stroke, atrial fibrillation (AF) is a key cause of ischaemic stroke. By allowing extended cardiac monitoring, implantable loop recorders (ILRs) may help enhance AF identification and secondary stroke prevention. Compared with standard therapy, this meta-analysis and systematic review assesses the effectiveness of ILRs in identifying AF and preventing recurrent stroke. Methods We searched Web of Science, Scopus, Embase and PubMed up to September 2024 following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses recommendations. Included were observational studies comparing ILR with conventional therapy in stroke or high-risk patients as well as randomised controlled trials (RCTs). AF detection, recurrent stroke and mortality were primary outcomes. Random-effects models were used to compute pooled HRs with 95% CIs. We looked at publication bias and heterogeneity. Results Included were 12 studies with four RCTs and eight cohorts. Compared with controls, ILR use was linked to a much greater AF detection rate (HR=3.13, 95% CI 1.97 to 4.97). Embolic events fell insignificantly (HR=0.81, 95% CI 0.65 to 1.02) and mortality showed no change (HR=1.01, 95% CI 0.77 to 1.31). Subgroup analysis showed more AF detection in RCTs than in cohort studies (p=0.035). Although no major publishing bias was found, heterogeneity was considerable. Conclusion By greatly enhancing AF detection in patients who had a stroke and at high risk, ILRs did not help to prevent secondary strokes. Therefore, they did not have enough efficacy in lowering recurrent stroke and death. Larger, more comprehensive studies are still required to clarify long-term therapeutic advantages and maximise patient selection. PROSPERO registration number CRD420251051946.