Measurement of coronary flow velocity reserve in the posterior descending coronary artery by contrast-enhanced transthoracic doppler echocardiography

Abstract

Background Although the measurement of coronary flow velocity (CFV) reserve (CFVR) in the left anterior descending coronary artery (LAD) by transthoracic Doppler echocardiography has been established, its success rate in the posterior descending coronary artery (PD) is still limited. Objective This study reports the feasibility and diagnostic accuracy of measuring CFVR in the PD by transthoracic Doppler echocardiography. Methods CFVR in both the distal LAD and the PD was measured in 151 consecutive patients before coronary angiography. PD flow was investigated under the guidance of a nondirectional Doppler color flow map with harmonic imaging in the modified apical 2-chamber view. Intravenous contrast agent, Levovist, was injected to enhance the CFV envelope at baseline and during hyperemia. Results CFVR was obtained in 145 patients in the LAD and 126 patients in the PD ( P < .001). The success rate of CFVR measurement in the PD was significantly higher in the last 50 patients (88%) than it was in the first 50 patients (72%) ( P < .05). CFVR in the PD was significantly lower for patients with significant stenosis of the artery supplying the PD than it was in those without stenosis (1.58 ± 0.59 vs 2.45 ± 0.72, P < .001). CFVR in the distal LAD was 1.40 ± 0.62 in patients with significant LAD stenosis and 2.45 ± 0.80 in those without stenosis ( P < .001). If a cut-off value of CFVR < 2 was used, sensitivity, specificity, and accuracy for the diagnosis of significant (>50%) stenosis of the artery supplying the PD were 84%, 83%, and 83%, respectively, whereas for the LAD they were 91%, 75%, and 80%, respectively. Conclusions Noninvasive measurement of CFVR in the PD could be obtained in the majority of unselected patients using a nondirectional Doppler color flow map and contrast-enhanced harmonic imaging. The diagnostic accuracy of CFVR in the PD is similar to that of the LAD and, hence, has a potential clinical use.