The measurement of collateral flow reserve (CFR; the hyperemic/baseline collateral flow velocity ratio) in patients with chronic total coronary occlusion requires invasive and expensive techniques. Noninvasive transthoracic coronary Doppler echocardiography may be an alternative option. Fifty-one patients with chronic total coronary occlusion were evaluated by transthoracic coronary Doppler echocardiography and venous adenosine infusion to measure CFR in occluded coronary arteries (the left anterior descending artery in 44 patients and the artery supplying the posterior descending artery in 7 patients). CFR data were plotted against 3 angiographic parameters: (1) grade of the epicardial filling of the occluded artery (1 ؍ absent, 2 ؍ partial, 3 ؍ complete), (2) stenosis of the donor artery, and ( Recently, transthoracic coronary Doppler echocardiography (TDE) has been introduced and validated for the noninvasive prediction of coronary artery disease, 1-4 the assessment of coronary recanalization in acute myocardial infarction, 5 and the evaluation of therapeutic coronary interventions. 6 -8 TDE can also predict left anterior descending (LAD) coronary occlusion on the basis of reversed flow in the epicardial artery 9 and in its perforating branches. 10 We undertook this study to (1) assess the feasibility of TDE to noninvasively measure coronary flow reserve of the collateral-dependent circulation distal to the occluding lesion and (2) determine the relation of collateral flow reserve (CFR) to the angiographic collateral anatomy and flow.
MethodsStudy population: We enrolled 56 consecutive patients (46 men, 10 women, mean age 59 Ϯ 9 years, range 43 to 75) with chronic total occlusion of the LAD (44 patients) and of the artery supplying the posterior descending coronary artery (PD; 12 patients). Inclusion criteria were (1) Thrombolysis In Myocardial Infarction anterograde coronary flow grade 0, (2) normal global and regional left ventricular function at rest (wall motion score index ϭ 1), and (3) the absence of Q-wave myocardial infarction. Patients with contraindications to adenosine administration were excluded. All patients were in sinus rhythm and fasting state and provided written informed consent. All coronary active medications were withdrawn the day before the Doppler study. Figure 1 shows the clinical model that we used: occluded coronary artery (either the LAD or the artery supplying the PD), visible collaterals toward the occluded artery, and good left ventricular function.TDE: TDE was performed as previously described in a modified 2-chamber view, 4,6 using Sequoia C256 and C512 ultrasound systems (Siemens-Acuson, Mountain View, California). The LAD was scanned by a dedicated 7-MHz transducer (3.5 MHz in color Doppler ultrasound) along the anterior interventricular groove, 6 and the PD was scanned using a standard 3.5-MHz transducer (2 MHz in color Doppler ultrasound). 4 The best long-axis view in color Doppler imaging was obtained to optimize the angle be-