OBJECTIVE This study was performed to examine the effect of dobutamine stress echocardiography on mitral regurgitation and to test the hypothesis that mitral regurgitation will increase in patients with an ischemic response. BACKGROUND New or worsening mitral regurgitation during stress testing has been proposed as a marker of ischemia. However, it is unclear whether ischemia induced by dobutamine is associated with mitral regurgitation because the hemodynamic effects of dobutamine may vary with regard to mitral regurgitation, depending on left ventricular function and maximal dose attained. METHODS Dobutamine stress echocardiography was performed in 102 consecutive patients with suspected or known coronary artery disease. Color flow Doppler was used to determine the presence and change in mitral regurgitation at baseline and peak dobutamine infusion (up to 40 micrograms/kg body weight per min). The mitral regurgitation color flow Doppler area was semiquantitatively graded as mild (< 4 cm2), moderate (4 to 8 cm2) or severe (> 8 cm2). Patients were assigned to ischemic and nonischemic groups according to the dobutamine stress echocardiographic results. RESULTS The two groups achieved the same maximal dose and demonstrated similar blood pressure and heart rate responses to dobutamine infusion. Only two patients developed new mitral regurgitation during dobutamine infusion, and both had a normal dobutamine echocardiographic result. More patients without ischemia had no mitral regurgitation compared with patients with ischemia. There was an insufficient number of patients with coronary angiographic data to determine the effects of mitral regurgitation on the sensitivity and specificity of dobutamine stress echocardiography. Of 23 patients with a rest ejection fraction < 50%, 61% had an improvement in mitral regurgitation grade compared with 25% of patients with a rest ejection fraction > or = 50% (p < 0.02). CONCLUSIONS These data indicate that although dobutamine infusion often improves mitral regurgitation in patients with left ventricular dysfunction during stress echocardiography, it does not induce or worsen mitral regurgitation in those who demonstrate an ischemic response. Future studies are necessary, with large numbers of patients, to determine the effects of mitral regurgitation on the sensitivity and specificity of dobutamine stress echocardiography.