The influence of collateral circulation on the detection of coronary artery stenosis by dipyridamole MIBI scintigraphy

Abstract

Dipyridamole is often used as an alternative to exercise in the detection of coronary artery disease by radionuclide techniques. For analyzing the dipyridamole-induced chest pain encountered during this test we studied a group of 47 patients who underwent MIBI SPECT imaging at rest and after the injection of up to 0.84 mg/kg dipyridamole. Coronary arteriography was available in a subgroup of 21 patients. A significant relation was found between chest pain during dipyridamole injection and ischemic electrocardiogram changes in the study group. In the subgroup of 21 patients with coronary angiography, an association was found between chest pain and the presence of collateral circulation. The MIBI perfusion defects were also more prevalent in the group with collaterals. These findings can be explained by the induction of coronary steal after dipyridamole in the group with a collateral circulation. This coronary steal causes real ischemia in the collateralized region. We conclude that in patients with known coronary artery disease, dipyridamole MIBI imaging allows for the selection of those patients with significant coronary stenosis with a collateral circulation. In this way, dipyridamole selects a group of patients who may be at lower risk in case of acute occlusion of the artery.