| ǥ : Clinical award session
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ȣ - 480320 16 |
| The significance of collateral circulation in acute myocardial infarction assessed by cardiac MRI |
| ¹Department of Internal Medicine, College of Medicine, ² Department of Diagnostic Radiology, College of Medicine, Pusan National University Hospital |
| Yong Hyun Park¹, June Hong Kim¹, Woo Suk Ko¹, Woo Hyung Bae¹, Hyeon Gook Lee¹, Kook Jin Chun¹, Taek Jong Hong¹, Ki Seok Choo², Chang Won Kim², Yung Woo Shin¹. |
Background : The significance of angiographic collateral flow in acute myocardial infarction (AMI) remains controversial. Prognosis after AMI relates to the size of infarcted myocardium and the magnitude of microvascular obstruction (MO) which can be directly measured by contrast-enhanced MRI. So we investigated whether collateral circulation after AMI had influence on MRI findings as a surrogate of clinical prognosis of patients. Methods : Twenty-two patients with AMI who underwent coronary angiography and MRI were included in this study. Antegrade flow of infarct related artery (IRA) was less than TIMI 3 flow and collateral feeding artery flow was TIMI 3 flow in all patients. All patients were treated by percutaneous coronary intervention within 5 days after onset of AMI. MRI were performed within 7 days after the intervention. The size of infarcted myocardium determined by the area showing hyperenhancement 15 minutes after contrast injection and the magnitude of MO determined by the area showing hypoenhancement 90 to 120 seconds after contrast injection were measured by planimetry. We defined ischemic territory as the segment between extension-lines that connect center of left ventricle to each lateral end of hyperenhancement. Four shor-axis cross sections in a patient were analyzed. Results : Baseline characteristics including distribution of IRA were not statistically different between the 4 groups according to Rentrope collateral grade. Area of MO was significantly smaller in patients with better collateral flow (collateral grade 0 : 2.46±1.69 cm², 1 : 2.02±1.94 cm², 2 : 0.89±1.99 cm², 3 : 0.54±0.87 cm²respectively, p<0.05). The ratio of MO area to ischemic area was significantly lower in patients with good collateral flow (grade 2/3 vs grade 0/1 : 9±13 vs 28±17%, p<0.01). On the contrary, the ratio of infarcted area to ischemic area was not significantly different (grade 2/3 vs grade 0/1 : 60±18 vs 65±16%, p=0.23). Conclusion : The presence of angiographically detectable collaterals may have impact on protecting microvascular damage at the core of infarcted myocardium rather than limiting infarct size only, thus having influence on the prognosis of patients with AMI.
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