Effects of balloon mitral valvuloplasty on systemic and regional left atrial levels of prothrombin fragment 1+2 in mitral stenosis.

A proportion of mitral stenosis patients with left atrial spontaneous echo contrast but without thrombus exhibit a regional hypercoagulable state, characterized by increased left atrial levels, but normal venous levels, of prothrombin fragment 1+2 (F1+2), a marker of thrombin generation. Valve dilatation by balloon mitral valvuloplasty has beneficial effects on left atrial spontaneous echo contrast, but its effect on left atrial thrombin generation is unknown. We examined the effects of balloon mitral valvuloplasty on venous and left atrial levels of F1+2 in 37 patients with mitral stenosis, divided into those with normal (group 1; n=22) and those with increased (group 2; n=15) regional left atrial thrombin generation, as described previously. The mitral valve area increased by a similar degree after the valvuloplasty procedure in the two groups. In group 1, the venous (P<0.005) and left atrial (P<0.0005) levels of F1+2 increased similarly after valvuloplasty, and as a result the left-atrial-venous F1+2 difference was unchanged. The venous F1+2 level also increased after valvuloplasty in group 2 (P<0.005); however, in contrast with group 1, the left atrial level decreased (P<0.03) and as a result the left-atrial-venous difference fell (P<0.05). These results show that balloon mitral valvuloplasty results in an immediate increase in thrombin generation, but a decrease in the left-atrial-venous F1+2 difference, in patients with increased left atrial thrombin generation. The divergent changes in venous and left atrial levels of F1+2 further highlight the limitations of assessing regional changes in coagulation activity by measuring venous levels of coagulation markers.