[Diagnostic value of exercise tomoscintigraphy with thallium 201 in patients with complete left branch block]

Eighteen patients with rate-dependent (n = 5) or chronic (n = 13) left bundle branch block underwent thallium 201 exercise SPECT and selective coronary arteriography. 15 patients showed significant septal or anteroseptal perfusion defects on the exercise scintigrams, but in only 4 of them did the coronary disease involve the left anterior descending artery (LAD) (n = 3) or the left main coronary artery (n = 1). Among patients with normal scintigrams, one had right coronary artery stenosis. Test performance in detecting individual coronary artery stenosis greater than 70 p. 100 was: sensitivity 80 p. 100 (4/5) and specificity 15 p. 100. In patients with left bundle branch block, T1 201 SPECT was indeterminate for LAD disease due to reversible septal perfusion defect. We conclude that the usefulness of stress thallium 201 SPECT in patients with left bundle branch block is very limited.