Left ventricular ejection performance and systolic muscle function in patients with mitral stenosis

Abstract

The status of systolic left ventricular (LV) performance in patients with isolated mitral stenosis (MS) is controversial. Potential alterations in LV architecture as well as loading conditions may have complex effects on LV ejection performance and muscle function. Therefore, we determined hemodynamic and angiographic LV ejection indexes (ejection fraction [EF], velocity of circumferential fiber shortening [Vcf] and stroke work index [SWI]), the level of preload (end-diastolic volume index [EDVI]), afterload (end-systolic wall stress [ESS]), and an index of LV contractile function thought to be independent of loading conditions (end-systolic wall stress/end-systolic volume index [ESS/ESVI]) in nine normal subjects and 16 patients with isolated MS. Although the EF in patients with MS (0.59 ± 0.03) was not statistically different from that in normal subjects (0.66 ± 0.04) (mean ± SEM), 31% of MS patients had an EF < 0.50. Vcf was lower in MS patients than in normal subjects (1.01 0.06 vs 1.32 ± 0.10 sec-1, p < 0.01), as were SWI (45.0 ± 2.9 vs 69.1 ± 3.9 g-m/m2 p < 0.001) and EDVI (71.3 ± 5.2 vs 93.0 ± 3.9 ml/m2 p < 0.005). End-systolic volume index (ESVI) was similar in MS patients and normal subjects (29.5 ± 3.6 vs 33.0 ± 3.6 ml/m2), whereas stroke volume index (SVI) was lower in MS patients (41.8 ± 2.8 vs 61.6 ± 4.4 ml/m2 p < 0.001). On the basis of ejection performance, MS patients were divided into two groups. Patients with normal ejection performance (MS(NEP)) had EF > 0.50 and Vcf > 1.00 sec-1. Patients with reduced ejection performance (MS(NEP) had EF < 0.50 or Vcf < 1.00 sec-1. Ms(REP) patients had higher ESS (157 ± 19 dyn · 103/cm2) than MS(NEP) (107 ± 11 dyn · 103/cm2) (p < 0.025), yet EDVI was similar in MS(REP) (70.6 ± 7.8 ml/m2) and MS(NEP) (72.0 ± 7.3 ml/m2). ESS/ESVI in MS patients was not different from that in normal subjects (5.3 ± 0.5 vs 5.2 ± 0.8 dyn · 103·m2/cm5). Even four of five MS patients with EF < 0.50 and all six MS patients with Vcf < 1.00 sec-1 had a normal ESS/ESVI. We conclude that MS patients as a group have reduced ejection performance and reduced preload. The reduction in ejection performance is due to increased afterload without adequate Frank-Starling compensation. LV muscle function, however, is normal in most MS(REP) patients.