[The role of coronary reserve in diagnosis of hemodynamically significant stenoses in anterior descending and right coronary arteries: transthoracic ultrasound study].

Analysis of possibilities of transthoracic echocardiography (TTEchoCG) diagnosis of hemodynamically significant stenoses of anterior descending and right coronary arteries (ADCA and RCA) based on Doppler assessment of coronary reserve (CR) was carried out in 73 patients with cardiac pain syndrome (mean age 48+/-7 years, 60 men, 13 women). As a referent method we used coronary angiography. Coronary blood flow at baseline and during administration of a vasodilator (dipyridamole up to 0.84 mg/kg) was assessed by broadband ultrasound transducer in the mode of noncontrast tissue second harmonic imaging in distal segments of ADCA and posterior interventricular artery (PIVA). CR was calculated as ratio of peak hyperemic to baseline diastolic coronary blood flow velocity. CR <2.0 was diagnosed as lowered. We found that TTEchoCG was simple noninvasive method of assessment of CR in distal thirds of ADCA and PIVA, which can be fulfilled in 90 and 86%of patients, respectively. We also revealed that hemodynamically significant stenoses of ADCA and PIVA caused CR lowering distally to zone of stenosis and that degree of CR lowering depended on severity of vascular narrowing. We found that CR<2.0 in distal third of ADCA was a predictor of its >50% narrowing with sensitivity 78%, specificity 85%, positive predictive value (PPV) 67%, and negative predictive value (NPV) 90%. In the presence of >70% ADCA stenosis sensitivity and NPV of the parameter reached 100%. We revealed that CR<2.0 in PIVA served as a marker of >50% RCA stenosis with sensitivity 88%, specificity 86%, PPV 68%, and NPV 95%. In the presence of >70% RCA stenosis sensitivity and NPV of the parameter rose up to 92 and 97%, respectively.