Predictive value of dipyridamole thallium imaging in a patient with myocardial bridging but without fixed obstructive coronary artery disease.

Both dipyridamole and exercise-201Tl imaging are sensitive, specific and of prognostic value in patients with suspected coronary artery disease, following myocardial infarction, and undergoing major noncardiac surgery. Though reported sensitivities and specificities vary widely from 60% to 100%, the consensus is that both are between 80% and 90% for both dipyridamole and exercise studies (23). Moreover, when compared directly in the same study populations, the two have equal sensitivities and specificities (9,11,13,23). Transient thallium perfusion abnormalities are the most consistent predictors of adverse cardiac events and have more predictive power than clinical and angiographic parameters. Thallium reversibility may be a better predictor of adverse cardiac events than angiography since it represents more of a physiologic rather than a purely anatomic evaluation of the heart. It is difficult to make an exact comparison of some of the studies in the literature because they use different patient populations, sometimes define coronary stenosis in different ways, may have different cardiac endpoints and may not differentiate between reversible and fixed thallium perfusion defects. Exercise has the advantage of a graded examination and more experience historically and is of importance in a detailed study of cardiopulmonary hemodynamics, as in cardiac transplantation. Dipyridamole is more useful in patients who cannot achieve symptom-limited, submaximal exercise. It may also be more useful for patients who are bedridden or have peripheral vascular disease. Angina occurs less frequently with dipyridamole.(ABSTRACT TRUNCATED AT 250 WORDS)