Significance of perfusion studies in the detection of transient myocardial ischemia.

In summary, myocardial thallium-201 imaging appears to be superior to exercise electrocardiography alone for detection of myocardial ischemia in patients with underlying coronary artery disease and chest pain. Risk stratification and prognostication can also be undertaken utilizing symptom limited stress scintigraphy in patients with stable chest pain syndromes or in conjunction with submaximal exercise thallium-201 scintigraphy after uncomplicated myocardial infarction. Patients with normal perfusion patterns or a single persistent defect have less likelihood of experiencing a subsequent cardiac event compared with patients with high risk scans demonstrating multiple defects in more than one vascular region or redistribution, or both. Thallium-201 imaging can be undertaken in the resting state in patients with unstable angina to detect "resting ischemia" or reversible vasospasm. Finally, the limitations of exercise or rest thallium-201 scintigraphy are discussed.