Differential Prognostic Value of Angiography-Derived Microcirculatory Resistance for Coronary Artery Bypass Grafting of Intermediate Coronary Stenosis

BACKGROUND For patients with intermediate coronary stenoses, the prognostic value of coronary artery bypass grafting (CABG) remains controversial. The prognostic impact of CABG may be different according to Murray law-based quantitative flow ratio (μQFR) and angiography-derived microcirculatory resistance (AMR) in patients with intermediate coronary stenoses. METHODS AND RESULTS Clinical data of 1411 cases who were diagnosed with multivessel coronary artery disease and had coronary artery intermediate stenoses (50% to 70% by visual assessment) between January 2013 and January 2020 were collected. Patients were categorized into CABG and defer groups based on the decision to bypass intermediate stenoses. These patients were further divided into different subgroups based on μQFR and AMR. The primary outcome was the major adverse cardiac and cerebrovascular events (MACCE), defined as a composite of cardiac death, target vessel myocardial infarction, target vessel revascularization and stroke. Multivariable analysis showed AMR (HR = 1.68, 95% CI 1.18-4.14, P = 0.008) was independent factor associated with MACCE in all patients. On receiver-operating characteristic (ROC) curve analysis, the estimated area under the curve was 0.75 (95% CI: 0.72-0.79) for MACCE. Using the maximum Youden’s index, the optimal cutoff value for AMR to predict MACCE was 2.50 mmHg*s/cm. In defer group, MACCE was significantly lower in patients with both μQFR > 0.80 and AMR < 2.50 mmHg*s/cm as compared with patients with μQFR > 0.80 (13.2% vs 22.0%, P = 0.031) or AMR < 2.50 mmHg*s/cm (13.2% vs 23.6%, P = 0.012) alone. Compared with patients with both normal μQFR and AMR, patients with both abnormal μQFR and AMR carried the highest risk for MACCE (HR = 3.46, 95% CI 2.10-5.71, P < 0.001). CABG was associated with a lower risk of MACCE compared with the deferral strategy when both μQFR and AMR were abnormal. In contrast, at normal μQFR and AMR, patients in both CABG and defer groups had similar MACCE outcomes. CONCLUSIONS In patients with intermediate coronary stenoses, the prognostic value of treatment strategy differed according to μQFR and AMR, with a significant interaction. The combination of μQFR and AMR can help stratify risk and guide treatment strategies for patients with intermediate coronary stenoses.