RELATIONSHIP OF TL-201 CLEARANCE ON EXERCISE STRESS MYOCARDIAL SCINTIGRAPHY TO CORONARY FLOW RESERVE IN PATIENTS WITH CORONARY-ARTERY DISEASE

Objective We evaluated thallium-201 (Th-201) clearance measurement dur ing exercise myocardial scintigraphy in patients with coronary artery disease, for the assessment of coronary circulatory function and diagn osis. Design The clearance rate of Th-201 was compared with the corona ry flow reserve measured by Doppler coronary flow velocimetry. Methods We selected 20 patients who had chronic stable angina with single-ves sel coronary artery disease of the left anterior descending artery (LA D) and underwent percutaneous transluminal coronary angioplasty (PTCA) , Ten control patients had atypical chest pain but no detectable heart disease, Regional net clearance of Th-201 was measured from the early and delayed bull's-eye images of Th-201 exercise stress single photon emission tomography (SPECT), Using a Doppler catheter, we also measur ed coronary flow reserve of the LAD, which was obtained by the intraco ronary administration of papaverine. Results The net Th-201 clearance in the anterior wall myocardium in the patients with coronary artery d isease before PTCA was significantly less than that in the controls, A t follow-up angiography after successful PTCA, it increased, The coron ary flow reserve before PTCA was also lower than that in the controls. It was increased immediately after PTCA, and was more markedly increa sed at the follow-up angiography. Before PTCA, regional net clearance in the anterior myocardium was correlated with the coronary flow reser ve of the LAD, The ratio for the net clearance of the anterior myocard ium at follow-up angiography to that before PTCA was also correlated w ith the ratio for coronary flow reserve. Conclusions In patients with coronary artery disease, the regional Th-201 clearance in the ischaemi c area measured by exercise Th-201 SPECT is correlated with the corona ry flow reserve of the affected artery, Moreover, the increase in the clearance rate after PTCA is also correlated with that in the coronary flow reserve. Thus the measurement of regional Th-201 clearance might be a useful non-invasive method of estimating of the coronary flow re serve.