Purpose: To compare the acute ischemic injury induced by occlusion of single coronary artery (OSCA) and stenosis of multi-coronary arteries (SMCA) using comprehensive Cardiac MRI.
Methods and Materials: We have studied 34 patients who had acute ischemic symptoms and received emergency coronary angiography and revascularization. Coronary angiogram confirmed that 15 patients had single coronary artery occlusion and 19 patients had multi-coronary artery stenosis. Cardiac MRI (CMRI) exam was performed 6-12 weeks after the coronary angiography and revascularization. CMRI protocol consisted of cine imaging of left ventricle, first-pass perfusion at rest and myocardial delayed enhancement (viability). In the patients with hypoperfused area, the signal intensity of the hypoperfused area and normal myocardium were both normalized by the blood pool signal. The normalized signal intensity was used to analyze the resulting images. The infarct size (hyper-enhanced volume) was presented as a percentage of LV mass (%LV), i.e the total number of hyperenhanced pixels divided by the total number of pixels of the LV myocardium and multiplied by 100.
Results: CMRI revealed that 11 of the 15 patients with OSCA had perfusion defect. However, only 4 of the 19 patients with SMCA had perfusion defect. The identified perfusion defects were confined to the endomyocardium of left ventricle. The signal intensity of the hypo-perfused region (1.56 ±0.89) was significantly lower than the normal myocardium (2.62 ± 1.148). The mean infarct size (28%) in the patients with OSCA was significantly larger than the mean infarct size (11%) in the patients with SMCA. Out of the 15 patients with single coronary artery occlusion, 10 patients had transmural hyper-enhancement and the remaining 5 patients had non-transmural and discrete hyper-enhancement. However, out of the 19 patients with multi-coronary artery stenosis, only 4 patients showed transmural hyper-enhancement and 15 patients had non-transmural and discrete hyper-enhancement.
Conclusion: CMRI demonstrated that the size of infarction induced by OSCA was much bigger than that induced by SMCA, which suggests that the occlusion of single coronary artery may induce severer irreversible myocardium damage than the stenosis of multiple coronary arteries. This study also demonstrated that there were larger percentage of patients with OSCA has perfusion defect than the patients with SMCA, which suggests that OSCA patients tend to have server microvascular obstruction than SMCA patients.