Application Of Fractional Flow Reserve In Chronic Total Occlusion

Objective:1.To investigate the degree of distal myocardial ischemia and collateral circulation function in patients with chronic total occlusion(CTO)by measuring the fractional flow reserve(FFR);2.To investigate the changes of the FFR of predominant donor vessel(FFRdon)before and after percutaneous coronary intervention(PCI)in patients with CTO;3.To investigate the value of FFR after original CTO vessel revascularization;4.To compare the changes of left ventricular ejection fraction(LVEF)in echocardiography before and after CTO.Method:Twenty-three CTO patients who met the inclusion criteria from November 2017 to October 2018 in the Department of Cardiology of Sichuan People's Hospital agreed to undergo FFR examination were finally collected.After collecting basic clinical data,percutaneous coronary intervention and FFR measurements were performed in patients with chronic total occlusion.All patients were given 200 ?g glyceryl trinitrate to prevent coronary spasm before PCI.The maximum hyperemia was induced by infusion of adenosine triphosphate disodium(ATP)at a rate of 140 ?g/kg/min through the left median elbow vein after the FFR value was stable.The FFR values of the predominant donor vessels(anterior descending,circumflex and right coronary artery)before and after CTO-PCI were measured routinely.When the guide wire arrives at the distal end of the occlusive segment through the occlusive lesion or the collateral branch in the opposite direction,the microcatheter is followed up and the pressure guide wire is exchanged to the distal end of CTO to measure the FFRcoll of the distal vessels of CTO.After stent implantation,the FFR of the distal part of the original CTO lesion is measured again through the forward guide catheter.The changes of hemodynamics and heart rate were also recorded during FFR measurement.In addition,the LVEF values of patients were recorded before CTO-PCI and 3 months after CTO-PCI.Major adverse cardiovascular events(MACE)were recorded within 3 months.Results:19 patients successfully completed CTO revascularization,FFR measurement and follow-up of 3 months after operation.FFR was significantly higher than FFRcoll(0.91±0.03 VS 0.37±0.09,P<0.001).FFRdon after operation was higher than FFRdon before operation(0.88±0.03 VS 0.86±0.05,P<0.001).FFRcoll was positively correlated with collateral Rentrop grading(r=0.844,P <0.001).FFRcoll was negatively correlated with CCS grading of angina(r=-0.854,P<0.001).There was a significant negative correlation between collateral Rentrop classification and CCS classification(r=-0.772,P<0.001).FFR was negatively correlated with FFRcoll(r=-0.460,P=0.046).Mean angina pectoris CCS grade after CTO-PCI was significantly lower than that before operation(P<0.001).The level of LVEF after operation was higher than that before operation(54.53±6.69 VS 48.89±10.60,P<0.001).Conclusion:1.Even with good collateral circulation,the myocardium of distal occlusion is still in ischemic state.2.After CTO-PCI,the FFRdon value of the predominant donor vessels was higher than that before operation.3.FFR of the original CTO lesion increased significantly after CTO-PCI,and no obvious ischemic changes were observed.4.The LVEF of three months after CTO-PCI was higher than that of preoperative LVEF.