Left atrial appendage occlusion indicated by increased thrombotic risk versus increased bleeding risk: a comparison of the stroke despite anticoagulation (STR-OAC) and EWOLUTION cohorts

Abstract Background Left atrial appendage occlusion (LAAO) provides mechanical cardioembolic protection, especially attractive for atrial fibrillation (AF) patients that cannot use oral anticoagulation therapy (OAC). Patients with prior stroke despite OAC are at high risk for recurrence and may also benefit from LAAO as (adjunctive) therapy. Purpose To investigate the efficacy of LAAO in AF patients with prior stroke on OAC compared to LAAO in AF patients with a contra-indication to OAC. Methods The STR-OAC LAAO is an international collaboration combining patients that underwent successful percutaneous LAAO because of a thrombo-embolic event or LAA thrombus on OAC from multiple LAAO registries (n=439). This cohort was compared to patients from the previously published EWOLUTION registry comprising of patients that successfully underwent LAAO because of a contra-indication for long-term OAC (n=1005). Thrombotic endpoints were prespecified and (non-procedural) major bleeding was defined as BARC score>2. Annualized event rates were calculated and compared to historical data based on individual patient risk scores. Results Both cohorts were comparable in terms of age and sex (Table 1). CHA2DS2-VASc and HAS-BLED scores were higher in the STR-OAC cohort. After LAAO indicated by a thrombotic event despite OAC, 33% of patients had a planned lifelong hybrid strategy approach of concomitant LAAO and OAC. Consequently, STR-OAC patients often continued OAC (with or without antiplatelet therapy), whereas EWOLUTION patients were more frequently discharged with antiplatelet therapy only. The annualized event rate (AER) for composite thrombotic events was slightly higher in the STROAC-LAAO compared to the EWOLUTION patients (4.2% versus 2.0%), possibly due to the higher thrombotic risk of this population. Major bleeding occurred more frequently in the EWOLUTION compared to STROAC-LAAO patients (AER 2.6% versus 1.1%, Table 2). In comparison to historically expected event rates, relative risk reduction (RRR) for thrombo-embolic events was 65% in the STR-OAC cohort, and 80% in the EWOLUTION cohort (Fig. 1). Annualized major bleeding rates were reduced with 81% and 46% in the STR-OAC-LAAO and EWOLUTION cohorts, respectively. Conclusions LAAO in AF patients with a thrombotic event despite OAC provides ischemic stroke protection similar to a guideline-recommended population with high bleeding risk. RRR for thrombotic events was more pronounced in the population contra-indicated for long-term OAC, while RRR for major bleeding was more pronounced in the patients that experienced a thrombotic event on OAC. Randomized trial data could endorse thrombotic event despite OAC as an indication for LAAO.Table 1&2Figure 1