Early Versus Delayed Insertable Cardiac Monitor Implantation After ESUS stroke and the Yield of Atrial Fibrillation Detection: a Systematic Review and Meta-analysis.

Background. The clinical utility of implantable cardiac monitors (ICMs) for atrial fibrillation (AF) detection following cryptogenic stroke or embolic stroke of undetermined source (ESUS) is well established. However, the optimal timing for ICM implantation to maximize diagnostic yield remains uncertain. Aims. To systematically review the literature and conduct a meta-analysis to determine whether earlier ICM implantation after cryptogenic stroke or ESUS ischemic stroke improves detection rates and reduces the time to AF diagnosis. Summary of review. A comprehensive search of PubMed, Embase, and Cochrane CENTRAL was conducted from inception to June 2025, without language restrictions. References of retrieved articles and relevant reviews were manually searched. We included observational studies or randomized trials reporting ICM use in patients with ESUS or cryptogenic stroke/TIA, providing data on AF detection rates and/or timing metrics (stroke-to-ICM interval, ICM-to-AF interval). Two reviewers independently screened studies and extracted data. Disagreements were resolved by consensus or third-party adjudication. Data were extracted following PRISMA guidelines. Study-level AF detection rates were modelled using logit-transformed proportions and pooled using random-effects models (REML). Mixed-effects meta-regressions assessed the effect of timing (stroke-to-ICM interval) on AF detection and diagnostic delay, adjusting for ICM monitoring duration. The primary outcomes were pooled AF detection rate and mean time from ICM implantation to AF diagnosis. Timing of implantation was assessed as a continuous and categorical (early, intermediate, delayed) variable. Forty-seven studies (N = 6,918 patients) were included. The pooled AF detection rate was 27.3% (95% CI: 24.6–30.2%), with substantial heterogeneity (I² = 80.8%). Early ICM implantation (<31.5 days from index event) was associated with a higher AF detection rate compared to delayed implantation (30.0% vs. 23.7%; p = 0.0017), independent of monitoring duration. Stratified meta-regression confirmed that delayed implantation was associated with lower AF detection even after adjusting for ICM duration.For each additional day of delay in ICM implantation, the time from the index event to AF diagnosis increased by an additional 0.32 days on average, even after accounting for monitoring duration (p = 0.0007). Conclusions. These findings suggest that earlier ICM implantation enhances AF detection after ESUS or cryptogenic stroke and shortens diagnostic delay. Optimizing timing of post-stroke monitoring may improve patient selection for anticoagulation and reduce recurrent stroke risk. CRD 420251064227.