Time-varying differences in stroke recurrence risk between types of atrial fibrillation based on screening methods and timing of detection.

Introduction: Atrial fibrillation (AF) burden progresses with time. Among ischemic stroke (IS) patients, AF can be detected at different burden progression stages based on the timing and screening method. We hypothesized that AF detected after IS on 12-lead ECGs (ECG-AF) and via 14-day-Holter prolonged cardiac monitoring (AFDAS) are linked to lower IS recurrence risk than AF known before stroke occurrence (KAF) because of being at an earlier progression stage than KAF. Additionally, we posited that IS recurrence risk differences between AF types vary over time due to their differential progression stages.

Patients and methods: Retrospective observational cohort study including IS/TIA patients with KAF, ECG-AF, and AFDAS [2018-2021]. Adjusted hazard ratios (aHR) were estimated using multivariable cause-specific Cox proportional-hazard models to compare IS recurrence between ECG-AF versus KAF and AFDAS versus KAF. Proportional hazards assumptions were tested to assess whether IS recurrence risk differences were time-varying.

Results: Of 758 AF patients (385 KAF, 236 ECG-AF, 137 AFDAS), 603 received anticoagulation and 59 experienced a recurrent IS after 1441 patient-years of follow-up. No IS recurrence risk differences were observed at the end of follow-up between ECG-AF and KAF (aHR 0.67, 95% CI 0.36-1.26), although ECG-AF showed lower risk only within the first year (aHR 0.15; 95% CI 0.04-0.56). AFDAS exhibited a lower IS recurrence risk than KAF (aHR 0.22, 95% CI 0.08-0.63), without time-varying differences.

Discussion: Differences in IS recurrence risk between ECG-AF and KAF varied over time. However, AFDAS showed a consistently lower IS risk than KAF throughout the entire study period.