Reversal of increased diastolic stiffness in mitral stenosis after successful balloon valvuloplasty

Background and aim of the study: Abnormal passive elastic properties have b een reported in patients with severe mitral stenosis and have been attribut ed to either: (i) chamber atrophy due to unloading; (ii) myocardial fibrosi s; (iii) right and left ventricular (LV) interaction; or (iv) internal rest rictions due to the rigid mitral valve apparatus. The study aim was to eval uate the effect of percutaneous mitral balloon valvuloplasty (PMV) on passi ve elastic properties in 19 patients with severe mitral stenosis. Ten patie nts with normal coronary arteries and LV function served as controls. Methods: LV high-fidelity pressure measurements and simultaneous biplane LV angiograms were obtained before and after PMV (n = 11). The constant of ch amber stiffness (b; ml(-1)) was calculated from the diastolic pressure-volu me relationship and the constant of myocardial stiffness (beta) from the di astolic stress-strain relationship. The time constant of relaxation (T; ms) was calculated from the LV pressure decay during isovolumic relaxation. Re gional ejection fraction (radial axis system) was determined in six regions of the right anterior oblique (RAO) and left anterior oblique (LAO) angiog raphic projections. Results: Mitral valve area was increased from 1.0 to 2. 2 cm(2) after PMV, whereas diastolic pressure gradient was reduced from 14 to 4 mmHg. Global LV ejection fraction (EF) was slightly reduced (57% versu s 63%; p<0.05) before valvuloplasty and normalized thereafter. Regional EF increased significantly (p<0.05) in the posterolateral region of the LAO pr ojection after intervention. Myocardial stiffness was increased before, and decreased significantly after balloon valvuloplasty (from 16 to 11; p<0.05 ). The rate of relaxation and chamber stiffness remained unchanged. Conclusions: Myocardial stiffness is increased in patients with mitral sten osis, but normalized after successful PMV. The improvement in passive elast ic properties after valvuloplasty can be explained by the mobilization of t he subvalvular apparatus with an improvement in regional LV function.