ADDITIONAL VALUE OF TL-201 SPECT TO A CONVENTIONAL EXERCISE TEST FOR THE IDENTIFICATION OF SEVERE CORONARY LESIONS AFTER AN EPISODE OF UNSTABLE CORONARY-ARTERY DISEASE

The additional value of thallium-201 SPECT to a conventional exercise test for the identification of patients with severe coronary lesions w as evaluated in 170 men, one month after an episode of unstable corona ry artery disease. Severe coronary lesions at coronary angiography - d efined as three vessel disease, left main stenosis or proximal left an terior descending artery stenosis as part of two vessel disease - were observed in 45.9%. In the SPECT image, the left ventricular myocardiu m was divided into nine segments and each segment was classified as ei ther normal (=0), reduced uptake (=1) or uptake defect (=2). The sum o f gradings in all segments post-exercise was denoted ''SPECT score''. The patients were divided into nine different groups regarding ST-depr ession during exercise (no ST-depression, ST-depression in 1-2 leads o r greater than or equal to 3 leads) and ''SPECT score'' (no SPECT scor e, 1-3 scores or greater than or equal to 4 scores). Severe coronary l esions were, in 68% identified by SPECT score greater than or equal to 4 and in 65% by ST-depression in greater than or equal to 1 lead at e xercise test. The specificity for identification of severe coronary le sions was, for both tests, 65%. SPECT score greater than or equal to 4 and/or ST-depression in greater than or equal to 3 leads identified 8 2% of the patients with severe coronary lesions with a specificity of 63%. Furthermore, SPECT score greater than or equal to 3 identified mo re patients with isolated proximal left anterior descending artery ste nosis than ST-depression alone at exercise test.