Relationship between the triglyceride-glucose index and coronary vascular function in patients with suspected...

Insulin resistance (IR) elevates the risk of coronary artery disease (CAD). The triglyceride-glucose (TyG) index is a reliable substitute indicator for IR. Computed tomography-derived fractional flow reserve (CT-FFR) and coronary flow reserve (CFR) effectively assess coronary vascular function. This study aimed to investigate the relationship between the TyG index and coronary vascular function assessed by CT-FFR and CFR in suspected CAD patients.

We enrolled 293 patients who underwent single-photon emission computed tomography (SPECT) along with coronary computed tomography angiography (CCTA), and analyzed the relationships among the CT-FFR, myocardial blood flow (MBF), CFR, and the TyG index.

Among the patients, those with a higher TyG index exhibited a relatively lower CT-FFR (0.80 vs. 0.85; P=0.02), rest-MBF (0.80 vs. 0.83; P=0.01), stress-MBF (1.92 vs. 2.26; P=0.01), and CFR (2.49 vs. 2.72; P=0.42). The TyG index was weakly and negatively correlated with the left ventricular (LV) CFR (r=-0.153; P=0.009). Among the patients without obstructive CAD, those with a high TyG index had a significantly lower CFR than those with a low TyG index (2.54 vs. 2.95; P=0.01), but no such significant difference was found in relation to the CT-FFR (0.91 vs. 0.93; P=0.72). Of the 879 vessels examined, 448 (51%) exhibited a reduced CFR. Compared with the vessels with a normal CFR, those with a decreased CFR exhibited a significantly increased obstructive CAD rate (40% vs. 29%; P<0.001), a lower CT-FFR (0.90 vs. 0.93; P<0.001), and a higher TyG index (8.81 vs. 8.67; P<0.001). In the vessels without obstructive CAD, the TyG index was higher in those with a reduced CFR compared with those with a normal CFR (8.80 vs. 8.59; P<0.001). The patient-level analysis revealed that male sex, the TyG index, obstructive CAD, and the CT-FFR were independently associated with the LV-CFR. The TyG index remained associated with the LV-CFR after adjustment for conventional risk factors. The TyG index remained independently associated with a reduced CFR in the patients without obstructive CAD.

The TyG index was independently associated with coronary vascular function, including both epicardial artery and microcirculatory function. The patients without obstructive CAD and those with a decreased CFR exhibited an increased TyG index, indicating a relationship between the TyG index and microcirculatory dysfunction. The TyG index, as a marker of metabolic health, was also related to microvascular injury. Our results provide insights into the association between the TyG index and coronary vascular function, which may inform clinical risk assessment.