Incidence and risk factors for thromboembolism and major bleeding in patients with mechanical valve prosthesis: A nationwide population-based study.

BACKGROUND: Risk factors of stroke/thromboembolism (TE) and major bleeding, and incidence of these events in specific age categories in warfarin-treated patients with mechanical heart valves (MHV) are uncertain. Our objective was to calculate event rates in specific age categories and identify risk factors for adverse events.

METHODS AND RESULTS: We identified 4,810 treatment periods with MHV between January 2006 and December 2011 in the Auricula and Swedish Web system for Enhancement and Development of Evidence-based care in Heart disease Evaluated According to Recommended Therapies registries. There were 3,751 treatment periods with aortic valve replacements (AVR) and 866 with mitral valve replacements (MVR). Median follow-up time was 4.5 years (IQR, 1.5-6.0). Time in therapeutic range with warfarin for patients with AVR was 74.2% for international normalized ratio of 2.0 to 3.0, with 72% of the patients having this target range. Rate of stroke/TE for AVR and MVR was 1.3 and 1.6 per 100 patient years, respectively (P=.20). The rate of first major bleeding was 2.6 and 3.9 per 100 patient years with AVR and MVR, respectively (P<.001). By multivariate analysis for AVR, age (hazard ratio [HR], 1.02; 95% confidence interval [CI], 1.01-1.03 per year) and previous stroke (HR, 2.4; 95% CI, 1.7-3.5) emerged as independent risk factors for stroke/TE. Heart failure (HR, 0.9; 95% CI, 0.6-1.4) and atrial fibrillation (HR, 1.0; 95% CI, 0.7-1.4) were not associated to stroke/TE. For major bleeding events, age (HR, 1.02; 95% CI, 1.01-1.03 per year) and previous major bleeding (HR, 2.5; 95% CI, 1.9-3.3) emerged as independent risk factors for AVR.

CONCLUSIONS: In a nationwide cohort study with MHV and high time in therapeutic range, heart failure and atrial fibrillation did not appear as risk factors of stroke/TE.