Complementary role of Doppler derived coronary flow reserve and left ventricular deformation parameters in detecting myocardial ischemia during dobutamine stress echocardiography

Background. Coronary flow reserve permits the physiological assessment of coronary stenosis and could be complementary to the wall motion information derived from qualitative and quantitative dobutamine stress echocardiography. The aim of this study was to evaluate whether assessment of coronary flow velocity (CFV) and coronary flow reserve (CFR) in left anterior descending coronary artery (LAD) by transthoracic Doppler echocardiography (TTDE) adds diagnostic information to both conventional 2D and strain-based dobutamine stress echocardiography (DSE). Methods. Thirty-six patients underwent DSE and subsequent coronary angiography. Wall motion score index (WMSI) was assessed with a 16-segment model. Regional WMSI in the LAD territory was determined at baseline and at peak stress in each patient. Systolic (Sw), early (Ew) and late (Aw) diastolic myocardial velocities were recorded at rest and during low and peak dobutamine doses in apical 4-chamber, 3-chamber and 2-chamber views. Strain rate (SR) and strain ( ) parameters were measured during systole, early diastole and late diastole in the same views. Velocity and strain traces were processed from the same wall site. CFV recording in the distal LAD was obtained by TTDE during DSE. CFR was calculated as the ratio of mean diastolic velocity at peak dobutamine to baseline mean diastolic velocity. Results. CFV was successfully recorded in 32 patients (89%) at baseline and during dobutamine infusion. CFR was significantly lower in patients with positive DSE compared to patients with negative DSE. Significant LAD stenosis (>50%) was identified in 24 patients. Peak CFR was 2.3 0.7 in the study population and 3.2 0.8 in patients without LAD stenosis (p<0.001). Sensitivity and specificity of abnormal CFR (<2) to detect LAD stenosis were 88% and 64%, respectively. WMSI had a sensitivity and specificity of 65% and 86%. Strain parameters had a sensitivity and specificity of 73% and 87%. In a regression multivariate analysis an abnormal CFR provided independent information compared to WMSI and SR (chi2 Model=32.45, incremental p value=0.0002). Conclusions. Thus, an abnormal CFR by TTDE adds diagnostic value to both conventional 2D and strain-based dobutamine stress echocardiography in detecting myocardial ischemia.