Value of Left Atrial Function on Hemodynamic Response in Patients with Mitral Stenosis: A Dobutamine Stress Echocardiographic Study

The mechanisms of different hemodynamic and clinical responses to dobutamine infusion in mitral stenosis are not clearly established. The aim of this study was to evaluate the relation between left atrial (LA) function and hemodynamic response in patients with mitral stenosis to dobutamine infusion and to explain this response related to this parameter. Forty-two consecutive moderately symptomatic patients (33 women, 9 men; mean age 46 ±9, range from 26 to 66), New York Heart Association (NYHA) class II with mitral stenosis (mean mitral valve area 1.7 ±0.1cm2) were evaluated with dobutamine stress echocardiography. Hemodynamic measurements were obtained at rest and peak dobutamine infusion. LA fractional shortening at rest was used as an index of global LA function. Twelve patients with hemodynamically serious mitral stenosis consisted of Group II (pulmonary artery pressure >60mmHg, transmitral mean gradient >15 mmHg during dobutamine infusion). The remaining 30 patients whose hemodynamic data did not reach the same level formed of group I. LA fractional shortening was significantly lower in group II compared to group I (19 ±3 vs 32 ±5 %, p<0.0001). In addition, left atrial dimension was significantly larger in group II (43 ±5 mm in group I vs. 50 ±2mm in group II, p<0.0001). While baseline hemodynamic parameters and mitral valve characteristics were not different in both groups, an increase in mean transmitral gradient (8 ±3 vs 5 ±2 mmHg, p<0.0001) and pulmonary artery systolic pressure (24 ±3 vs 16 ±8 mmHg, p= 0.007) were significantly greater in group II compared to group I during dobutamine infusion. Left atrial fractional shortening was negatively related to the increase in transmitral mean gradient (r:-0.58, p<0.01). We that hemodynamic response during dobutamine stress echocardiography correlated with LA fractional shortening in patients with mitral stenosis. In some patients with mitral stenosis patients, manifest elevation in hemodynamic parameters may depend on impaired left atrial function accompanying left atrial enlargement.