Collateral Circulation and 99m Tc - MIBI Heart SPECT in Patients with Totally Coronary Occlusion

Son, Kyung Hwan; Kim, Kown Sam; Lee, Moo Yel; Lee, Won Ho; Kim, Deog Yoon; Kang, Heung Sun; Choe, Chung Whee; Kim, Myung Sik; Song, Jung Sang; Bae, Jong Hwa

Abstract

OBJECTIVES
The role of coronary collateral circulation in protecting myocardium after the occlusion of a supplying artery has long been debated. Recent date show that the coronary collateral circulation may partially prevent ischemia and preserve myocardial contractile function. The purpose of this study was to evaluate the relation between the grades of collateral circulation and perfusion scores of 99mTc-Heart SPECT in patients with totally coronary occlusion.
METHODS
We studied 44 patients with totally coronary occlusion who had been hospitalized at Kyung Hee University hospital between October, 1989 and May, 1994, Patients were classified into two groups; Group 1: patients with angina pectoris (n=21), Group 2: patients with myocardial infarction (n=23). Angiographic collateral circulation was graded from 0 to 3: 0=none, 1=filling of side branch only, 2=partial filling of the epicardial segment, 3=complete filling of epicardial segment. The perfusion score of dipyridamole stress 99mTc-MIBI Heart SPCET was analyzed with angiographic findings. Resting and stress echocardiography were analyzed to identify left ventricular wall motion abnormalities.
RESULTS
1) When LAD was totally occluded, there were hishevcrgree of collateral circulations from RCA in group 1 and group 2. When RCA was totally occluded, there was higherdesree of collateral circulation from LAD in group 1 and group 2. 2) The degree of collateral development was higher in group 1 than in group 2 (2.5+/-0.7 vs. 1.8+/-1.0, p<0.05). 3) In 99mTc-MIBI Heart SPECT, there was no significant difference of perfusion score at stress but perfusion score was significantly higher in group I than in group 2 at rest. 4) In 99mTc-MIBI Heart SPCET, there was no difference of perfusion score between totally coronary occlusion territories in group 1 and more than 50% coronary artery stenotic territories in group 1 and group 2. 5) In stress echocardiography, ten of the 13 patients showed normal LV wall motion at rest, but 9 of these 10 patients showed LV wall motion abnormalities at stress in group l. In group 2, all 10 patients showed LV wall motion abnormalities at rest and 3 of these patients showed more aggravation of LV wall motion abnormalities.
CONCLUSION
Collateral circulation in angina patients can prevent myocardial ischemia and preserve myocardial function at rest, but not at exercise. Collateral circulation in patients with myocardial infarction cannot preserve myocardial function at rest. and exercise. Dipyridamole stress 99mTc-MIBI Heart SPECT is one of the indirect quantification methods to evaluate collateral development and coronary flow reserve.