Superiority of dipyridamole over exercise testing when exercise thallium imaging is limited by angina.

The extent of jeopardized myocardium can be underestimated on stress thallium myocardial perfusion images when exercise tolerance is limited by angina pectoris. A patient's tolerance for pain can influence the degree of myocardial ischemia observed on myocardial perfusion images during effort angina. A case is reported of a patient with angina pectoris showing mild ischemia limited to one myocardial segment on exercise thallium images, but severe and extensive reversible perfusion defects during dipyridamole-thallium imaging, and a 70% stenosis of the left main coronary artery on coronary angiography.