TDI-STI-based dobutamine stress echocardiography and Doppler-derived coronary flow reserve in ischemic heart disease

Purpose. 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. Forty-five patients underwent DSE and subsequent coronary angiography. 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 and strain rate (SR) and strain (e) parameters were obtained at rest and during low and peak dobutamine doses in apical 4-chamber, 3-chamber and 2-chamber views by Tissue Doppler Imaging (TDI) and Speckle Tracking Imaging (STI). CFR in the distal LAD was calculated as the ratio of mean diastolic velocity at peak dobutamine to baseline mean diastolic velocity. Results. CFV was successfully recorded in 41 patients (91%). Peak CFR was 2.2±0.9 in the study population and 3.3±0.6 in patients without LAD stenosis (p< 0.001). Sensitivity and specificity of abnormal CFR (< 2) to detect LAD stenosis were 88% and 66%, respectively. WMSI had a sensitivity and specificity of 63% and 87%. TDI and STI strain parameters had a sensitivity and specificity of 72% and 88% and 74% and 89%, respectively. In a regression multivariate analysis an abnormal CFR provided independent information compared to WMSI and SR (χ2 Model=33.17, incremental p value=0.0002). Conclusions. Abnormal CFR by TTDE adds diagnostic value to both conventional 2D and strain-based dobutamine stress echocardiography in detecting myocardial ischemia