[Evaluation of hemodynamic significance of arteriovenous coronary fistulas: diagnostic integration of coronary angiography and stress/rest myocardial scintigraphy].

PURPOSE: We report on the importance of the integration of data obtained from digital coronary angiography and stress/rest 99mTc sestamibi myocardial perfusion single photon emission tomography in evaluating the hemodynamic significance of coronary arteriovenous fistulae.

MATERIAL AND METHODS: Coronary fistulae were detected with coronary angiography in 9 patients. All patients underwent clinical examination, transthoracic echocardiography, stress electrocardiogram and stress/rest 99mTc sestamibi myocardial perfusion single photon emission tomography.

RESULTS: Stress/rest 99mTc sestamibi myocardial perfusion single photon emission tomography and stress electrocardiogram showed stress-induced myocardial ischemia in 2 patients. The first patient with familial predisposition and risk factors for ischemic heart disease presented a mesocardic heart murmur on clinical examination. At stress ECG (125 Watt, 153 b/m' max frequency 93%, arterial pressure 230 mmHg, max frequency pressure product 35,200) ischemic alterations were recorded at the first minute of the second stage of the Bruce protocol. Coronary angiography detected a circumflex artery fistula in the coronary sinus. Stress/rest 99mTc sestamibi myocardial perfusion single photon emission tomography for the evaluation of stress/rest perfusion detected a reversible perfusion defect of the proximal portion of the posterolateral and lateral walls, thus confirming the hemodynamic importance of the flow through the fistula during stress cycloergometric testing. In the second patient familial predisposition to ischemic heart disease and previous inferior wall myocardial infarction and non-significant stress ECG, coronary angiography identified a subocclusive stenosis of the right coronary artery and an anomaly between the anterior interventricular artery and the left pulmonary artery. The presence of the contrast medium in the left pulmonary artery identified a flow from the left ventricle to the left pulmonary artery. Good angiographic results were obtained after percutaneous coronary angiography of the right coronary artery stenosis. Due to the onset of angina stress/rest 99mTc sestamibi myocardial perfusion single photon emission tomography was performed to evaluate stress/rest perfusion (75 Watt, 125 b/m', 88% max frequency, arterial pressure 200 mmHg, double max product 25,000 with ST depression of 1.5 mm in V1-V4) and identified an irreversible perfusion defect due to infarction and a reversible perfusion defect of the anterior wall and apex due to ischemia caused by the anomalous flow through the coronary fistula. The correspondence between the site of the coronary artery where the fistula originates, identified by coronary angiography, and the reversible perfusion defects, identified by stress/rest 99mTc sestamibi myocardial perfusion single photon emission tomography, indicates that the anomalous flow through the fistula may cause myocardial ischemia. The irreversible perfusion defects of the inferior wall are the result of right coronary artery subocclusive stenosis.

CONCLUSIONS: Coronary fistulae cause myocardial ischemia only in a small number of patients. Data obtained from single photon emission tomography in evaluating stress/rest myocardial perfusion, correlated with data from coronary angiography, have shown that changes in patients with terminal coronary anomalies may be due to different coronary diseases: ischemia to anomalous flow through the fistula and myocardial infarction to subocclusive right coronary artery stenosis. Stress/rest 99mTc sestamibi single photon emission tomography for the evaluation of myocardial perfusion is a reliable means of assessing the functional importance of the terminal coronary anomalies detected by coronary angiography. Evaluation of the hemodynamic importance of the coronary fistulae is indispensable in programming corrective surgery.