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From Affiliated Egyptian Universities and Cardiology Centers

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Background: Previous studies that investigated the effects of coronary collateral circulation on myocardial perfusion were compromised by inclusion of patients with multivessel coronary artery disease, incomplete occlusion, prior myocardial infarction, or a combination of these.
Methods: In this study we will investigate the relationship between angiographic collateral circulation and myocardial perfusion in patients with total occlusion of a single coronary artery, in the absence of myocardial infarction or significant stenosis in the other coronary arteries supplying the same myocardial territory.
Results: Forty patients underwent stress myocardial single photon emission computed tomography within 90 days of angiography. Collateral circulation was present in 24 patients (Group A) and absent in 16 patients (Group B). Reversible perfusion defects were present in 22 (91.7%) patients in group A and in 12 (75%) in group B, comparison between both groups came back statistically insignificant (p-value=NS). Group A included 4 (18.2%) patients with a small size defect (<5%), 9 (40.9%) patients with a moderate perfusion defect (5-10%) and 9 (40.9%) patients with a large perfusion defect (>10%); while group B had 2 (16.6%) patients with small perfusion defect, 5 (41.6%) patients with a moderate perfusion defect and also 5 (41.6%) patients with a large perfusion defect, comparison between both groups came back statistically insignificant (p-value=NS). The mean exercise time for patients in group A was 6.9±0.92 minutes and their mean achieved peak METs was 7.35±0.35 METs. On the other hand; the mean exercise time for patients in group B was 6.9±0.83 minutes and their mean peak METs was 7.23±0.25 METs. Comparison between both groups also appeared to be statistically insignificant (p-value=NS).
Conclusions: In patients with a single-vessel total coronary occlusion and without myocardial infarction, stress-induced myocardial ischemia is almost always present, irrespective of presence or absence of angiographic collaterals. These data suggest that coronary collaterals do not appear to protect against stress-induced perfusion defects. Nevertheless collaterals in our study did not have any positive impact on the functional capacity of patients, predicted by the analysis of exercise duration and achieved peak METs.
Keywords: Coronary artery total occlusion, Collateral circulation, Myocardial perfusion, CTO.
(Heart Mirror J 2009; 3(2): 80-85)