ASSESSMENT OF ANATOMIC AND PHYSIOLOGICAL SEVERITY OF SINGLE-VESSEL CORONARY-ARTERY LESIONS BY DIPYRIDAMOLE-ECHOCARDIOGRAPHY - COMPARISON WITH POSITRON EMISSION TOMOGRAPHY AND QUANTITATIVE ARTERIOGRAPHY

Background The aim of this study was to compare the results of dipyrid amole-echocardiography test (DET: two-dimensional echo monitoring duri ng dipyridamole infusion up to 0.84 mg/kg over a period of 10 minutes) with both anatomic and physiological parameters of coronary artery di sease severity, assessed by computer-assisted quantitative coronary ar teriography, and regional coronary how reserve, measured by [N-13]ammo nia ((NH3)-N-13) and dynamic positron emission tomography (PET), respe ctively. Methods and Results We studied 31 patients with a history of chest pain and neither previous myocardial infarction nor resting wall motion abnormalities. Eighteen patients had single-vessel disease (>5 0% stenosis of one major coronary vessel), and 13 had normal coronary arteries. The criterion for DET positivity was the appearance of a new transient regional wall motion abnormality. In patients with a positi ve DET, two parameters were evaluated: the dipyridamole time tie, the time from the beginning of drug infusion to the development of obvious dyssynergy) and the wall motion score index (WMSI, a semiquantitative integrated estimation of extent and severity of the stress-induced dy ssynergy). WMSI was derived by summation of individual segment scores divided by the number of segments interpreted. Quantification of regio nal myocardial blood flow was obtained by PET measurements of (NH3)-N- 13 arterial input function and left ventricular myocardial tissue conc entration both at control and after dipyridamole (0.56 mg/kg over 4 mi nutes). Maximal regional blood flow after dipyridamole in the region s upplied by the stenotic vessel was significantly lower in the 11 patie nts with coronary artery disease and positive DET than in the 7 patien ts with coronary artery disease and negative DET (1.08+/-0.33 versus 1 .98+/-0.37 mL.min(-1).g(-1), P<.01). In patients with a positive DET, regional coronary flow reserve correlated well with dipyridamole time (r=.87, P<.01) but not with peak WMSI (r=.25, P=NS). Patients with dip yridamole-induced akinesia or dyskinesia (n=6) had a greater reduction in regional coronary flow reserve than did those showing hypokinesia (n=5): 1.38+/-0.51 versus 2.17+/-0.42, P<.05. Percent area reduction w as more severe in patients with DET positivity than in those with DET negativity (93.7+/-8.7% versus 77+/-10.3%, P<.01), and it correlated w ith regional coronary how reserve (r=.64, P<.01) and dipyridamole time (r=-.59, P<.01). Conclusions In patients with single-vessel disease, DET shows an excellent specificity but a limited sensitivity; in these patients, DET positivity is associated with a physiologically importa nt coronary stenosis. Severity of the anatomic stenosis and impairment in regional flow reserve are greater when the dipyridamole-induced dy ssynergy appears earlier during the test. Therefore, a stratification of the anatomophysiological severity of coronary artery disease can be obtained with DET, based mainly on the temporal allocation of the tra nsient dyssynergy.