The Relationship Between Left Atrial Mechanical Function and Functional Capacity in Mitral Stenosis

In this study, left atrial functions of patients with rheumatic mitral stenosis and sinus rhythm, which was determined by transthorasic echocardiography, was compared with those of healhty subjects and the association of left atrial functions with functional capacity was investigated in subgroup analyses. Material and Method: 32 patients with isolated rheumatic mitral stenosis (median age was 39.1 +/- 11) (group 1) and 20 patients in the control group (median age was 37 +/- 8,2) (group 2) were enrolled to study. The average mitral valve area of patients was 1.1 +/- 0,3 cm2. When patients were divided according to New York Heart Association (NYHA) classification; 16 patients were NYHA 2 (Grup A) and 16 patients were NYHA 3 (Grup B). Left atrium diameters, left atrium volume, left atrium fractional area change and left atrium ejection fractions of patients in these groups were calculated. Results: Left atrium ejection fraction (LAEF) and left atrium fractional area change (LAFAC) that were determined echocardiographycally were significantly lower in patients with mitral stenosis (32 +/- 5, 44 +/- 3; p<0.001-25 +/- 11.32 +/- 6; p< 0.02). When patients were divided according to New York Heart Association ( NYHA) classification; 16 patients were NYHA 2 (Grup A) and 16 patients were NYHA 3 (Grup B). There were not any asymptomatic patients and no patients were NYHA 4. The clinical and echocardiographic data of patients are shown in table 2. Despite of similar mitral valve area and average mitral gradient, systolic pulmonary artery pressure was found to be higher in symptomatic group. But there was no difference between left atrial functions of the two groups. Discussion: In this study we have shown that left atrial functions determined echocardiographically can decline in patients with mitral stenosis but the correlation with symptomatology is poor. These findings suggest that there is such a mechanism like Frank Starling in the left atrium. The mild increase in preload (volume and pressure) provides the contiuation of left atrial functions while the additional increase in preload causes destruction of correspondance of contraction between left atrial myofibrils and thus left atrial disfunction occurs. For this reason the value of left atrial ejection as a parameter reflecting clinical sypmtomatology is decreased.