[Mechanisms of impaired coronary flow reserve in patients with aortic stenosis: transthoracic Doppler echocardiographic study].

OBJECTIVES: Development of left ventricular hypertrophy in severe aortic stenosis is associated with coronary microcirculatory dysfunction, as demonstrated by impaired coronary flow reserve. Recently, coronary flow reserve can be assessed noninvasively by transthoracic Doppler echocardiography (TTDE). This study assessed the relationship between coronary flow reserve obtained by TTDE and the hemodynamic parameters and left ventricular mass index in patients with aortic stenosis. METHODS: Consecutive 29 patients (15 men, 14 women, mean age 72 +/- 11 years) with isolated mild to severe aortic stenosis were studied using TTDE to assess coronary flow reserve. Peak transvalvular pressure gradient across the aortic valve (peak AVG) and aortic valve area were measured by TTDE. Left ventricular mass index was measured by echocardiography. RESULTS: There were significant correlations between coronary flow reserve and peak AVG (r = -0.570, p = 0.001), left ventricular mass index (r = -0.620, p < 0.001), aortic valve area (r = 0.740, p < 0.001), and left ventricular rate pressure product (r = -0.660, p < 0.001). Multiple regression analysis showed that aortic valve area and peak AVG were independent factors for coronary flow reserve (p < 0.001, p = 0.048). CONCLUSIONS: Impairment of coronary flow reserve in patients with aortic stenosis is related to aortic valve area and peak AVG, rather than the degree of left ventricular hypertrophy.