Prevalence of clinically significant bradyarrhythmias in patients implanted with loop recorders for cryptogenic stroke: a manifestation of atrial cardiomyopathy?

Background: Cryptogenic stroke is often associated with atrial fibrillation (AF), but may also reflect a broader atrial pathology such as atrial cardiomyopathy (AtCM). While implantable loop recorders (ILRs) are used primarily to detect AF in these patients, the burden of bradyarrhythmias is not well established. Objective: To evaluate the prevalence and clinical significance of bradyarrhythmias in patients implanted with ILRs after cryptogenic stroke or TIA, compared to a matched control population with ILRs for other indications. Methods: We retrospectively analyzed 225 patients receiving ILRs for cryptogenic stroke/TIA (n=139) or other indications excluding syncope (n=86). Bradyarrhythmias were classified according to ESC 2021 guidelines. A 1:1 propensity score matching (PSM) was performed based on major covariates. The primary endpoint was the time to first detection of clinically significant SND. Results: During a median follow-up of 23 months, SND occurred more frequently in the cryptogenic stroke group than in controls (18.7% vs 4.7%, p=0.003). After PSM (n=114), SND remained significantly more prevalent in stroke patients (22.8% vs 8.8%, p=0.04). Univariate analysis identified cryptogenic stroke/TIA (OR 3.14, 95% CI 1.02-9.64, p=0.045), hypertension, and increased indexed left atrial volume as independent predictors of SND. Kaplan-Meier analysis showed a significantly lower event-free survival for SND in the cryptogenic stroke group (log-rank p=0.034). Conclusion: Cryptogenic stroke patients show a significantly higher and earlier incidence of clinically relevant SND compared to matched controls, which may suggest an underlying atrial remodeling process consistent with atrial cardiomyopathy. These findings underscore the importance of comprehensive arrhythmic monitoring beyond AF in this population.