Myocardial imaging with thallium 201 at rest and during exercise. Comparison with coronary arteriography and resting and stress electrocardiography

Abstract

Myocardial imaging with i.v. thallium-201 (201Tl) was performed at rest and following maximal treadmill exercise in 101 patients with suspected coronary artery disease. Results were interpreted from Polaroid scintiphotos by 3 independent observers with complete interobserver agreement in 79%. Of 25 patients with no or insignificant coronary artery disease (<50% diameter stenosis), 1 (4%) had a resting 201Tl image defect, 1 (4%) had an exercise 201Tl defect, none had an ECG Q wave, and 4 (16%) had exercise ST-segment depression. Among 76 patients with coronary artery disease (≥50% diameter stenosis), 58 (76%) had a defect on either the rest or exercise 201Tl image. The proportion of patients with an exercise image defect (50/76, 66%) was greater than the proportion with exercise ST depression alone (34/76, 45%; P < 0.02). Overall, 69 of the 76 (91%) patients with coronary artery disease had either a positive rest or exercise myocardial image and/or a positive rest (ECG Q waves) or exercise (ST depression) electrocardiogram. This exceeded the proportion with only rest or exercise electrocardiographic abnormalities (50/76, 65%; P < 0.001). The authors conclude that rest and exercise myocardial imaging with 201Tl is easily accomplished with readily available imaging equipment. The image data enhanced the diagnostic sensitivity of stress electrocardiography, and provided spatial identification of the abnormal segment(s) of myocardium.