Adenosine infusion is safe. Vasodilator and negative dromotropic side effects are generally well tolerated. Serious side effects are relatively rare, and they reverse with termination of adenosine infusion. Interpretable radionuclide studies were obtained in 98.7% of patients and aminophylline reversal was seldom required.

We conclude that 1) anomalous coronary arteries are associated with a high incidence of hypertension and valvular heart disease in the sample of patients studied; 2) there was a high incidence of palpitations, but this and the other symptoms were difficult to evaluate because of the associated disease; 3) in certain patients with anomalous origin of the left main coronary artery (LM) from the right sinus of Valsalva, myocardial perfusion is probably impaired and may be associated with serious cardiac events whether the initial course of the LM is posterior to the aorta, between the aorta and the pulmonary artery, and/or anterior to the pulmonary artery. Course of the anomalous LM coronary artery between aorta and the pulmonary artery may be associated with sudden death. Atherosclerosis of a single coronary artery proximal to its branching is an additional liability to the anomaly. Since sudden death occurs most commonly in young individuals with anomalous origin of the LM, special care should be taken to evaluate young patients with chest pain resembling angina. A maximal treadmill exercise test should be performed first, and if there is evidence of ischemia, a coronary arteriogram should be performed. Recognition of anomalous origin of coronary arteries and their course also is important in patients undergoing surgery for aortocoronary bypass or for valvular heart disease when perfusion of coronary arteries is needed.MANY VARIATIONS of the aortic origin of one or both coronary arteries exist" 2 and have been considered minor coronary anomalies without clinical significance.' With the increasing use of coronary arteriography, the anomalies are being recognized more frequently and their clinical significance is becoming better appreciated.3 8The variations in the initial course of the coronary arteries with anomalous origin are more important than the anomalous origin itself. Unrecognized coronary anomalies may lead to errors in clinical

In medically treated patients with coronary artery disease, exercise SPECT thallium imaging provides independent and incremental prognostic information even when catheterization data are available. The extent of the perfusion abnormality is the single most important prognostic predictor.