Diagnosis of coronary artery disease by Doppler echocardiography during dobutamine stress

This study sought to determine whether Doppler echocardiography is valuable in detecting coronary artery disease during dobutamine echocardiography (DE) in patients with normal resting wall motion. The accuracy of DE depends on the clarity of images and the experience of interpretators. Doppler echocardiography is suspected to be able to overcome these weak points. Doppler echocardiography was performed during dobutamine stress in 42 patients with coronary artery disease and in 38 subjects with normal coronary arteries. We focused on the changes of the Doppler-derived left ventricular isovolumic relaxation time (IVRT) and the corrected IVRT, which is the IVRT corrected for heart rate. These isovolumic relaxation variables shortened with the initial increment of dobutamine dosage and markedly prolonged during myocardial ischemia. The Δcorrected IVRT, defined as the difference between the corrected IVRT at low-dose dobutamine stress (10 μg/kg/min) and at peak stress, was found to be the most powerful indicator of ischemia. The sensitivity and specificity of DE was 85% and 89%, respectively. For the purpose of a high sensitivity (90%) in identifying coronary artery disease, a Δcorrected IVRT of more than 12 msec was used without a significant reduction in specificity (84%) as compared to DE. This Doppler-derived corrected IVRT offers high sensitivity in detecting coronary artery disease and can improve diagnostic accuracy in conjunction with DE.