Stress/rest myocardial perfusion SPET in evaluation of the hemodynamic significance of a fistula between the anterior descending branch of the left coronary and the left pulmonary arteries.

This paper describes the use of Stress/Rest Tc-99m Sestamibi (MIBI) Single Photon Emission Tomography (SPET) to evaluate the hemodynamic significance of an unusual fistula between the descending anterior branch of the left coronary artery and the left pulmonary artery. Coronary arteriography in a patient with myocardial infarction of the inferior wall revealed subocclusive (greater than 90%) stenosis of the right coronary and an abnormal branch proceeding from the intermediate section of the left anterior descending (LAD) artery to the left pulmonary artery. Treatment of the stenosis by percutaneous transluminal coronary angioplasty gave a good angiographic result but failed to resolve the angina. Myocardial Stress/Rest Tc-99m MIBI SPET disclosed an irreversible defect corresponding to the previous infarction. The anterior wall and apex were marked by a reversible defect due to a flow steal via the abnormal branch running from the intermediate section of the LAD artery to the left pulmonary artery. The examination was thus able to reveal perfusion defects in two different sites and of different size and gravity. Its findings and the coronary angiography data showed that these defects were caused by different coronary disorders (atherosclerosis of the right coronary artery and a coronary arteriovenous fistula of the LAD artery). It also demonstrated the functional importance of the LAD to the left pulmonary artery coronary fistula.