Risk of thromboembolic and bleeding events in patients with atrial fibrillation after valvular intervention in either aortic or mitral position

Abstract

Abstract Background The optimal oral anticoagulant treatment (OAC) for patients with atrial fibrillation (AF) undergoing valvular intervention is uncertain. Mitral valve prostheses are believed to be more thrombogenic than the aortic due to lower flow velocity across the valves. The only randomized controlled trial of AF patients with biological valve prostheses included only patients receiving mitral valve prostheses (1). It is unclear if these findings could be extrapolated to patients receiving aortic valve prostheses. Purpose To describe baseline characteristics and comorbidities of patients receiving biological valve prostheses in aortic or mitral valve position and to investigate possible associations between valve position and the incidence of cardiovascular (CV) death, ischemic stroke or systemic embolism and major bleeding. Methods All patients in Sweden undergoing open heart surgery with aortic or mitral valve replacement with biological prostheses between 2010-2016 with known AF were included. The study cohort was identified in the SWEDEHEART registry. Information on comorbidities, drug exposure and occurrence of outcome events was collected from SWEDEHEART and other national registries. Association between the position of valve prosthesis (mitral and aortic) and incidence of outcome events was investigated using Cox regression analysis. Multivariable adjustments were made for comorbidities. Results In total, 2359 patients with AF underwent aortic (n=2103) or mitral (n=256) valve replacement. The median age was 75 and 73 years, respectively. Hypertension, diabetes mellitus and previous TIA were more common in the aortic valve group, whereas heart failure and previous major bleeding was more frequently observed in the mitral group. In both groups, about 50% of the patients were not on OAC treatment at time of discharge from valve intervention, despite that the mean CHA2DS-VASc score was 3.3 and 3.2, respectively. Mitral valve prostheses were associated with similar risk of CV death (hazard ratio (HR) 1.09; 95% confidence interval (CI), 0.77 – 1.56), ischemic stroke and systemic embolism (HR 1.27; 95% CI, 0.85-1.92) compared to aortic valve prostheses. In contrast, receiving mitral valve prosthesis was associated with lower risk of major bleeding compared to aortic prosthesis (HR 0.58; 95% CI 0.38 – 0.88). Conclusion(s) The study indicated similar risk of CV death, ischemic stroke and systemic embolism among patients with AF undergoing valve replacement with biological prostheses in either aortic or mitral position. Mitral valve replacement was associated with lower risk of major bleeding.