Determinants of left ventricular function in isolated rheumatic mitral stenosis.

Left ventricular end-diastolic volume (preload), peak systolic wall stress (afterload), instant Emax (contractility index = peak systolic left ventricular pressure/end-systolic volume), left ventricular mass, left ventricular ejection fraction (LVEF) alone and normalised for mass index, were studied in 30 patients with isolated rheumatic mitral stenosis (group 1) and compared with 24 normal individuals (group II) who served as control. Preload was not different in the two groups (p = NS), afterload was increased in group I (p = 0.01), while LVEF, Emax, left ventricular mass and mass normalised LVEF were reduced in mitral stenosis as compared to normal control (p less than 0.01- less than 0.001). Comparison of patients with reduced ejection performance (LVEF less than 50%, n = 9, group IA) with those having normal LVEF (n = 21 group IB) revealed increased left ventricular end-diastolic volume and reduced left ventricular mass, mass normalised ejection fraction and Emax (in IA p less than 0.05). Peak systolic wall stress was comparable in these two subgroups. This study shows that the major determinant of left ventricular dysfunction in isolated rheumatic mitral stenosis is impaired contractility and not the loading factors.