DETERMINANTS OF DEPRESSED LEFT-VENTRICULAR EJECTION FRACTION IN PURE MITRAL-STENOSIS WITH PRESERVED SINUS RHYTHM

Background and aim of the study: Although depressed left ventricular e jection fraction is present in a considerable proportion of subjects w ith pure mitral stenosis (MS), its mechanisms are not clearly identifi ed. The purpose of this study was to identify determinants of depresse d ejection fraction in young patients with isolated mitral stenosis in sinus rhythm. Methods: We retrospectively analyzed 320 records of pat ients with MS (mitral valve area equal to or less than 2.0 cm(2)) who underwent invasive diagnostic procedure in our center. Of these 39 sub jects aged 20-40 years with isolated MS in sinus rhythm were selected for the final analysis. Results: An ejection fraction not exceeding 50 % was found in 12 patients (group A). When comparing group A to the re mainder (group B), group A patients had lower left ventricular end-dia stolic volume indices (60.5 +/- 21.6 ml/m(2) vs. 76.1 +/- 16.1 ml/m(2) , p = 0. 02) and stroke volume indices (28.0 +/- 10.4 vs. 47.9 +/- 12. 0, p < 0. 001). No significant differences between the groups in patie nts' age, end-systolic volume index, mitral valve area, mean transmitr al gradient, left-sided cardiac pressures, pulmonary wedge pressure, s ystemic vascular resistance, and cardiac output were found. Indices of left ventricular isovolumic contraction and relaxation as well as end -systolic indices of left ventricular function were also comparable. G roup A had significantly higher pulmonary rhythm. vascular resistance, pulmonary artery pressures, and higher heart rate. An approximate ind ex of left ventricular compliance was significantly lower in group A w ith similar left ventricular minimal and end-diastolic pressures. Conc lusions: Depressed ejection fraction in pure mitral stenosis with pres erved sinus rhythm seems attributable to left ventricular underfilling that appears to be precipitated by other factors in addition to a nar rowed mitral orifice, e.g. decreased passive left ventricular complian ce and/or altered interventricular interactions.