AIM To analyze the relationship between collateral pressure index of coronary chronic total occlusion (CTO) and distal myocardial perfusion of occlusion and to investigate the effect of different perfusion levels of occluded distal end on myocardial perfusion recovery and cardiac functions after CTO revascularization.
METHODS Patients who had been diagnosed with coronary chronic total occlusion by coronary angiography were enrolled from 2018-1-1 to 2018-10-30 in Xijing Hospital. Myocardial contrast echocardiography (MCE) was performed before revascularization to evaluate myocardial perfusion by some parameters, including peak intensity A, blood flow velocity β and myocardial blood flow A×β. After CTO revascularization, coronary wedge pressure (Pw) was measured by a temperature-pressure guide wire and collateral pressure index (CPI) was calculated from Pw. Patients were divided into two groups according to CPI≥2.5 or CPI<2.5 and the difference of A, β and A×β were compared between the two groups. In addition, according to semi-quantitative analysis of MCE, perfusion-defects group and perfusion-delay group were divided by myocardial perfusion levels of distal occlusion and the difference of recovery of perfusion and cardiac function after CTO revascularization was analyzed between the two groups.
RESULTS There was no difference in myocardial perfusion levels of distal occlusion between CPI<0.25 group and CPI>0.25 group. A(4.88±0.64)dB, (5.78±0.82)dB, P<0.01 and β (14.08±2.41)s, (16.17±2.24)s, P<0.01 in perfusion-defects group were significantly lower than those in perfusion-delay group. No significant difference was found in β and A×β between perfusion-defects group and perfusion-delay group at 1 day and 1 month post CTO-PCI. A in perfusion-defects group was lower than that in perfusion-delay group at both 1 day (6.14±0.82)dB, (6.91±0.93)dB, P = 0.01 and 1 month post CTO-PCI (7.71±1.07)dB, (8.52±1.02)dB, P<0.05. Before CTO-PCI, the ejection fraction in perfusion-defects group was lower than that in perfusion-delay group (0.45±0.07), (0.49±0.04), P<0.05. One month after CTO-PCI, the ejection fraction in perfusion-delay group was higher than that before PCI (0.50±0.03), (0.49±0.04), P<0.05. However, compared with the ejection fraction before PCI, no significant difference was found in perfusion-defects group 1 month post CTO-PCI (0.45±0.07), (0.45±0.06), P = 0.54.
CONCLUSION Collateral pressure index cannot predict distal myocardial perfusion of CTO before CTO revascularization. After CTO revascularization, the recovery of myocardial perfusion is not affected by collateral pressure index. The recovery of cardiac functions and distal myocardial perfusion of CTO are subject to the level of original myocardial perfusion of the CTO territory.
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