Supplementary Material for: Long-term Outcome of Patients with Atrial Fibrillation and High Risk of Stroke treated with Oral Anticoagulation or Left Atrial Appendage-Occlusion – A Cardinality Matched Analysis

Introduction: Atrial fibrillation (AF) poses a significant risk of stroke. Left atrial appendage occlusion (LAAO) is an alternative for patients with contraindications to oral anticoagulation (OAC) or with high risk of bleeding. This study aims to compare the outcomes of LAAO versus conventional stroke prevention in high-risk AF-patients. Methods: This secondary analysis incorporates data from the prospective Swiss-AF and Beat-AF cohorts, and the Zurich LAAO Registry. Cardinality matching was performed to create two comparable cohorts: conventional treatment (92% OAC) and LAAO. The primary endpoint was a composite of stroke, cardiovascular (CV) death, and clinically relevant bleeding. Kaplan-Meier method with competing risk analysis was used. Results: Each group included 468 patients (age 76.4 [70.5, 82.0] years, 33% female). The LAAO group exhibited higher baseline bleeding risk (HAS BLED 2.0 [1.0 to 3.0] versus 3.0 [3.0 to 4.0]; p<0.001). Median follow-up time: 6.0 [4.7 to 7.0] years in conventional treatment group and 4.0 [1.5 to 6.1] in LAAO group. No significant difference in the primary composite endpoint (HR 0.87, 95% CI: 0.72 to 1.06, p=0.18), stroke risk (HR 1.14, 95% CI: 0.66 to 1.97, p=0.64), or CV mortality (HR 1.08, 95% CI: 0.82 to 1.42, p=0.60) was observed between groups. LAAO correlated with a significantly lower risk of clinically relevant bleeding (HR 0.61, 95% CI: 0.47 to 0.80, p<0.001). Conclusion: In this cardinality matched analysis with long-term follow-up, LAAO showed similar stroke and CV death rates but lower clinically relevant bleeding risk compared to conventional therapy in high-risk AF-patients.