Transthoracic echocardiography (TTE) has been described as an accurate technique for noninvasive evaluation of coronary flow reserve (CFR) of the left anterior descending artery (LAD) and posterior descending artery (PDA). Aim of this study was to find out whether serial measurement of CFR in LAD and PDA using TTE allows detection of stenosis elimination after intracoronary intervention and is a marker of successful procedure.
Methods: The study group comprised 14 patients with single-vessel coronary disease (stenosis 82+/-14%) of the LAD (9 patients) or right coronary artery (RCA, 5 patients) scheduled for stent implantation. All patients underwent dipyridamole stress echo with CFR evaluation of either distal LAD or PDA 1 day before and 6-9 days after successful stent implantation. CFR was calculated as the ratio of hyperemic to basal peak diastolic velocity. A CFR value of <2.0 was considered abnormal.
Results: Adequate Doppler signals to measure CFR were obtained in 13 patients (93%). Abnormal pre-procedure CFR value was revealed in 12 assessed patients (92%). Significant increase of CFR due to a decrease of coronary flow velocity at rest and its more pronounced hyperemic rise was found in all patients after stent implantation (CFR: 1.28+/-0.52 before and 2.53+/-0.37 after stenting; p<0.001). Using a cut-off value of CFR more or equal 2.0 to identify absence of significant coronary artery disease, TTE detected successful stent implantation with a sensitivity of 91.7% and specificity of 100% for both LAD and RCA. CFR was still abnormal in only 1 patient with pre-procedure>90% LAD stenosis.
Conclusion: TTE is a feasible technique for serial CFR evaluation in LAD and PDA. Cut-off CFR value more or equal 2.0 is a sensitive and specific criterion of successful stent implantation in LAD and RCA.
Keywords: left anterior descending artery; percutaneous coronary intervention; right coronary artery; transthoracic coronary flow reserve.