Ethnic differences in clinical outcomes following major bleeding in atrial fibrillation patients: a report from two prospective regional registries in Europe and Asia

Aims To investigate differences in clinical presentation and prognosis between East Asians and Europeans with atrial fibrillation (AF) who have experienced major bleeding (MB).Methods and results We analysed two prospective registries enrolling AF patients from the Asian-Pacific Heart Rhythm Society (APHRS) and EURObservational Research Programme (EORP). Ethnicity was inferred by enrolment country. Major bleeding was defined as intracranial haemorrhages or significant extracranial bleeding. Primary outcomes included all-cause mortality and major adverse cardiovascular events (MACE). Logistic regression was utilized to explore clinical characteristics associated with prior MB. Cox models were constructed to assess the risk of primary outcomes in patients with and without a history of MB. Interaction analyses were performed to investigate the differences between the two cohorts. Out of the 597 patients with prior MB (3.8% of total cohort), 221 (37.0%) were East Asian. Patients with prior MB were older, more commonly East Asians, and had a higher cardiovascular burden than those without MB. A history of MB was associated with lower use of oral anticoagulants (OAC) [odds ratio (OR) 0.44, 95% confidence interval (CI) 0.35-0.54], particularly vitamin K antagonists (OR 0.73, 95% CI 0.59-0.90). Though associations for prior MB with MACE [hazard ratio (HR) 0.98, 95% CI 0.72-1.33] and thrombo-embolic events (HR 0.87, 95% CI 0.46-1.65) were not significant in entire population, they were more pronounced in East Asians compared to Europeans (P for interaction = 0.032 and 0.004, respectively).Conclusion Following MB, East Asian patients with AF might be more susceptible to MACE and thromboembolism when compared to Europeans.In this report from two large prospective observational registries in East Asia and Europe, we defined ethnicity by enrolment country and compared clinical presentation and prognosis between East Asians and Europeans with atrial fibrillation (AF) who have experienced major bleeding (MB). Our main findings are as follows:Compared to Europeans, East Asians with AF were more prone to experience MB, and tended to be treated with rhythm control opposed to rate control strategy following MB.Impact of prior MB on subsequent risk of MACE and thromboembolism events appeared greater in East Asians compared to Europeans.