Coronary flow velocity reserve in three major coronary arteries by transthoracic echocardiography for the functional assessment of coronary artery disease: a comparison with fractional flow reserve

Abstract

Coronary flow velocity reserve (CFVR) measurement in three major coronary arteries by transthoracic echocardiography is a promising and non-invasive method for detecting myocardial ischaemia. Its value when compared with fractional flow reserve (FFR) is unknown. Our aim was to determine the diagnostic accuracy of CFVR in three major coronary arteries for detecting ischaemia compared with FFR. This is a prospective study in 172 vessels of 140 patients with at least one ≥50% stenosis in a major epicardial artery as determined by visual assessment on computed tomography coronary angiography. We performed CFVR measurement by transthoracic echocardiography within 48 h before coronary angiography and FFR measurement. The cut-off value of CFVR was estimated by the receiver operating characteristic (ROC) curve based on that of FFR ≤0.75. The CFVR was 1.86 ± 0.36 in coronary arteries with FFR ≤0.75 (n = 79) and 2.54 ± 0.48 in those with FFR >0.75 (n = 93, P < 0.0001). CFVR with cut-off of 2.2, determined by the ROC curve, was 85% sensitive and 79% specific in predicting the stenotic condition of the coronary artery with FFR ≤0.75 in three major vessels. In each vessel, the sensitivity and specificity were 85 and 78% (left anterior descending coronary artery), 94 and 83% (right coronary artery), and 88 and 88% (left circumflex coronary artery). CFVR was indirect proportional to FFR (r = 0.56, P < 0.0001) and to per cent diameter stenosis (r = 0.26, P = 0.0008). The non-invasive CFVR measurement could be a reliable stenosis-specific method for determining the haemodynamic significance of three major coronary arteries.