Assessment of mitral flow velocity with exercise by an index of stress-induced left ventricular ischemia in coronary artery disease

Exercise-induced myocardial ischemia results in both diastolic and systolic left ventricular (LV) dysfunction. To investigate the utility of Doppler assessment of LV diastolic function with exercise, 28 consecutive patients underwent digital stress echocardiography, including measurement of mitral flow velocity by pulsed-wave Doppler and simultaneous stress thallium imaging. The mean mitral flow velocity was measured as the integrated area under the LV diastolic inflow Doppler spectral display. The change in mean mitral flow velocity from baseline to immediate postexercise was compared among 3 patient groups: (1) patients with thallium redistribution or exercise-induced wall-motion abnormalities, or both, consistent with exercise-induced ischemia (n = 18), (2) patients with no evidence of stressinduced ischemia, with or without resting wall-motion abnormalities (n = 10), and (3) 10 control subjects of similar age with normal resting 12-lead electrocardiograms, normal resting and postexercise 2-dimensional echocardiograms and normal electrocardiographic treadmill stress testing. The percent increase in mean mitral flow velocity was 101% (± 59) for controls and 86% (± 53) for patients without stress-induced ischemia versus 33% (± 24) in patients with stress-induced ischemia (p < 0.005). An increase in mean mitral flow velocity with exercise of >50% correctly identified 9 of 10 nonischemic control patients. An increase in mean velocity of <50% predicted ischemia in 15 of 18 patients with evidence of stress-induced ischemia (p < 0.005) Thus, Doppler assessment of LV diastolic function with exercise expressed as a change in the mean velocity of mitral flow is a useful indicator of stress-induced ischemia.