Incidence of thromboembolism, major bleeding and mortality in patients with mechanical heart valves

Abstract

Background: Previous studies have reported rather low incidences regarding thromboembolism (TE) and bleeding in patients with mechanical heart valves (MHV), during oral anticoagulation treatment with warfarin, despite wide treatment ranges of international normalized ratio (INR) and poor time in therapeutic range (TTR). Methods: We conducted a complete study of all 546 patients which were followed in two centres who have undergone MHV replacement, for thromboembolism (TE), major bleeding and mortality during 2008-2011. Results: In total there were 398, 122 and 26 patients in the aortic, mitral and the combined aortic/mitral valve groups respectively. The mean (±SD) age were 68 (14), 69 (15) and 66 (17) respectively. A total of 56 TEs were documented in all patients, resulting in an incidence of 2.86 per 100 patient-year. The aortic valve patients had 37 TEs (2.56 per 100 patient-year), and mitral valve patients 17 TEs (4.01 per 100 patient-year). A total of 80 major bleedings were documented (4.09 per 100 patient-year). The aortic valve group had 60 (4.16 per 100 patient-year) and the mitral 19 (4.45 per 100 patient-year). TTR (INR 2-4) in centre 1 was 91.8% and 76.4% in centre 2 (INR 2-3). By multivariate analyses, significant predictors of TE were heart failure (Odds ratio [OR]: 2,17; 95% confidence interval [CI]: 1.17-4.02; p=0.01) and vascular disease (OR: 3.22; 95% CI: 1.05-9.85; p=0.04). Predictors of bleeding were previous hemorrhage (OR: 3.1; 95% CI: 1.64-5.89; p=0.001) and age > 75 (OR: 1.7; 95% CI: 1.01-2.8; p=0.047). 75 patients died during the follow up (3.83 per 100 patient-year), resulting in a standardized mortality ratio of 3.0 (CI: 2.4-3.8; p<0.001) compared to the general population of centre 1. Conclusion: The incidence of TE, major bleeding and total mortality in this study exceed previous reports despite high TTR and give additional risk estimates for clinical decision making.