Role Of Fractional Flow Reserve (FFR) Measurement In Strategy Making For Percutaneous Coronary Intervention (PCI) In Patients With Coronary Artery Disease

BackgroundThe incidence of coronary artery disease (CAD) increased significantly during recentyears. A lot of younger patients were diagnosed as CAD which has become one of theserious threats to human health. Quantitative coronary angiography (QCA) describesseverity of coronary artery stenosis which has been considered as the "gold standard" forCAD diagnose. Although QCA gave information about the severity of coronary arterystenosis, the functional severity of coronary artery stenosis can not be predicted by QCA.QCA can not used be for evaluating myocardial ischemia assotiated coronary arterystenosis for multivessel coronary artery disease. Strategy making is not easy for coronarybifurcation lesions according to QCA.Several studies has demonstrated that coronary artery stenosis detected by QCA do nothave the linear relationship with myocardial ischemia. PCI which CAD will relieve thesymptoms of patients, reduce the incidence of adverse cardiovascular events and improvepatient outcomes. However, PCI in non-ischemic related lesions does not improve the patient’s symptoms. The incidence of cardiovascular events in those patients is similar topatients subjected to medical treatment. Therefore, previous complete revascularization(stenosis＞50%) according to QCA is not appropriate. CAD patients should receive"functional" complete revascularization (only the myocardial ischemia-related lesionsneed revascularization).Fractional flow reserve (FFR) is a technique used in coronary catheterization to measurepressure differences across a coronary artery stenosis and to determine the pressure behind(distal to) a stenosis related to the pressure before the stenosis. FFR is considered to be anepicardial coronary specific functional parameters of coronary artery disease. FFR hasbeen used to evaluate left main disease, multivessel coronary artery disease, diffuse longlesions, bifurcation lesions, and et al. For multivessel coronary artery disease, FFR canaccurately identify myocardial ischemia-related target lesions and achieve "functional"revascularization. For coronary bifurcation lesions, FFR is benificial for making strategiesto treat coronary bifurcation lesions, deciding single or double stents strategy, andevaluating whether the side branch need stenting after main vessel stenting. However, FFRis not a routine procedure in China. The relationship between FFR and QCA is not wellinvestigated in Chinese patients. The role of FFR in detecting ischemia related coronaryartery stenosis and making strategies for coronary bifurcation lesions are not wellunderstood.Objectives1. To explore the correlations between quantitative coronary angiography parameters andFFR value;2. To explore the correlation between quantitative coronary angiography (QCA)parameters and fractional flow reserve (FFR) value. To illustrate the role of FFR inguiding PCI in patients with multivessel coronary artery disease;3. To explore the effects of left anterior descending (LAD) coronary artery stentimplantation on the first diagonal (D1) coronary artery. To illustrate the role offractional flow reserve (FFR) in guiding PCI strategy in patients with coronary arterybifurcation lesions. Methods1. This study included231patients (325lesions with intermediate coronary arterystenosis) with coronary artery disease accommodated in Xijing Hospital from Mar2011to Mar2013. All of the patients received coronary angiography, QCA evaluationand FFR evaluation. Patients were divided into two groups: FFR＞0.80(n=177) orFFR≤0.80(n=148).2. This study included96patients with218coronary artery lesions. Patients were dividedinto two groups: FFR＞0.80(n=113) or FFR≤0.80(n=105).3. This study included63patients with LAD coronary artery lesions. Patients weredivided into two groups according to the FFR value of D1after LAD stentimplantation: FFR＞0.80(n=48) or FFR≤0.80(n=15).Results1. There were significant difference of percentage diameter stenosis (58.7±13.4vs68.2±11.6, P＜0.001) and percentage area stenosis(80.9±11.7vs88.4±8.0, P＜0.001)between groups. Percentage diameter stenosis and percentage area stenosis werenegatively correlated with FFR value (r=-0.352，P＜0.001，r=-0.347，P＜0.001). Theminimum luminal diameter was statistically different between groups (1.18±0.46vs0.83±0.39, P＜0.001) and positively correlated with FFR value (r=0.374，P＜0.001).Receiver operating characteristic (ROC) analysis showed that minimum luminaldiameter≥1.05mm was the best cutoff value to predict FFR＞0.80with sensitivity62.7％, specificity73.6％;2. There were significant difference of percentage diameter stenosis（59.1±13.8vs66.2±10.5, p＜0.001）and percentage area stenosis（81.4±10.9vs87.3±7.7, p＜0.001）between groups. Percentage diameter stenosis and percentage area stenosis were notcorrelated with FFR value (r=-0.286，p＜0.001，r=-0.282，p＜0.001). The minimumluminal diameter was significant different between groups（1.18±0.49vs0.86±0.36, p＜0.001）and it is also positively correlated with FFR value (r=0.364，p＜0.001). QCAdetected26patients with three vessel disease and70patients with two vessel disease. However, FFR value suggested that only10patients had three vessel disease,29patients had two vessel disease and17patients had one vessel disease. Mismatchesand reverse mismatches between diameter stenosis (QCA) and FFR value were21(9.6%) and53(24.3%) respectively. Mismatches between area stenosis (QCA) andFFR value was89(40.8%);3. There were no significant difference of LAD reference diameter (3.30±0.17vs3.34±0.27, p=0.882), LAD percentage diameter stenosis (0.89±0.10vs0.88±0.12,p=0.934）, LAD lesion length (20.5±6.4vs22.7±8.9, p=0.765), LAD FFR value beforePCI (0.65±0.11vs0.63±0.15, p=0.837), D1reference diameter (2.62±0.17vs2.63±0.19, p=0.794), D1percentage diameter stenosis after PCI (0.47±0.24vs0.58±0.20, p=0.109), D1minimum luminal diameter after PCI (1.39±0.62vs1.12±0.55, p=0.141) between groups. The D1FFR value after LAD PCI had statisticaldifference between groups (0.91±0.05vs0.69±0.04, p＜0.001). After LAD PCI, QCArevealed8cases (16.7%) of diameter stenosis≥70%in the FFR＞0.80group and10cases (66.7%) of diameter stenosis＜70%in the FFR≤0.80group.Conclusions1. Percentage diameter stenosis, percentage area stenosis and minimum luminal diameterof quantitative coronary angiography (QCA) parameters were correlated with FFRvalue. However, the sensitivity and specificity of QCA in predicting ischemia relatedlesions were not well. FFR is recommended in differentiating ischemia related lesionsfrom non-ischemia related lesions;2. FFR measurement in patients with multivesselcoronary disease significantly reducestarget lesions when compared with standard angiography-guided PCI;3. FFR measurement in patients with coronary bifurcation lesions significantly reducescomplexity of PCI procedures when compared with standard angiography-guided PCI.