Anticoagulation in Atrial Fibrillation Associated with Mitral Stenosis

Rheumatic valve disease is present in 0.4 % of the word population, mainly in lowincome countries. Rheumatic mitral stenosis affects more women and between 40 to 75 % of patients may have atrial fibrillation (AF), more frequently in upper-middle income countries. This rhythm disturbance is due to increased atrial pressure, chronic inflammation, fibrosis, and left atrial enlargement. There is also an increase in the prevalence of AF with age in patients with mitral stenosis. The risk of stroke is 4 % per year. Success rates for cardioversion, Cox-Maze procedure, and catheter ablation are low. Therefore, anticoagulation with vitamin K antagonist is mandatory for Evaluated Heart valves, Rheumatic or Artificial (EHRA) classification type 1. However, this anticoagulation is used by less than 80 % of those eligible and less than 30 % have the international normalized ratio in the therapeutic range. The safety and efficacy of using rivaroxaban, a direct factor Xa inhibitor anticoagulant, were demonstrated in the RIVER trial with a sample of 1005 patients with AF and bioprosthetic mitral valve. The indication for valve replacement, that is, if severe mitral stenosis or severe mitral regurgitation, was not specified. A randomized, open-label study (DAVID-MS) is underway to compare the effectiveness and safety of dabigatran and warfarin therapy for stroke prevention in patients with AF and moderate or severe mitral stenosis. Thus, the applicability of the use of direct anticoagulants in patients with AF and mitral stenosis and also in those undergoing mitral bioprostheses surgery will be the subject of further studies. The findings may explain if specific atrial changes of mitral stenosis even after the valve replacement will influence thromboembolic events with direct anticoagulants.