Abstract DP115: Atrial Fibrillation may be Pathogenic in Half of Patients with Cryptogenic Stroke or TIA: The ANTARCTICA Individual Patient Data Meta-analysis

Background: Insertable cardiac monitoring (ICM) detects atrial fibrillation (AF) in substantial proportions of cryptogenic stroke, non-cryptogenic ischemic stroke without known AF, and non-stroke patients who are at risk of underlying AF. Given differences in patient characteristics across studies, there may be differences in AF detection rates on ICM across these subgroups that have not been identified. We investigate whether AF detection rates on ICM are higher in cryptogenic stroke or TIA (C-IS/TIA) patients compared to individuals with non-cryptogenic stroke or without stroke when accounting for differences in study populations. Methods: This is an individual-participant data (IPD) meta-analysis of prospective studies and randomized controlled trials (RCTs) of ICM in C-IS/TIA, non-cryptogenic ischemic stroke, and non-stroke patients. Multi-level multivariable logistic regression models were used to test whether C-IS/TIA is associated with increased AF detection relative to other categories. We performed multiple imputation to derive values for variables with <20% missing data and Rubin’s rules to estimate adjusted odds ratios (aOR) by combining 100 post-imputation datasets. The primary outcome was detection of AF. The attributable risk was derived by application of Bayes Theorem. Results: Two RCTs and 12 prospective studies were included with a total of 1562 C-IS/TIA patients and 474 non C-IS/TIA. In adjusted multi-level logistic regression analyses, AF detection was higher in C-IS/TIA patients (aOR 1.90; 95%CI 1.18-3.06, p=0.009), indicating that 47% of AF detected in C-IS/TIA may be pathogenic. Limiting the comparator group to ischemic stroke or history of stroke yielded similar results (aOR 2.83 95% CI 1.47-5.44, p = 0.002). Days to AF detection was significantly shorter in C-IS/TIA patients (median 65 vs. 169, p<0.001). Conclusion: In this IPD meta-analysis of patients undergoing ICM, AF detection was higher in C-IS/TIA patients, with shorter time to AF detection compared to non-cryptogenic/non-stroke individuals. These findings suggest that nearly 50% of the AF detected in patients with C-IS/TIA may be pathogenic.