Percutaneous coronary intervention (PCI) remains a cornerstone therapy in the management of coronary artery disease (CAD), particularly in patients presenting with acute coronary syndromes.1, 2, 3 However, despite technical success and adherence to guideline-directed medical therapy, long-term adverse cardiovascular events (CVEs) continue to pose a substantial risk in post-PCI populations.4,5 This underscores the clinical imperative for effective tools to stratify risk and optimize secondary prevention in the chronic phase following revascularization.

Among contemporary noninvasive physiological assessment techniques, the quantitative flow ratio (QFR) has emerged as a promising alternative to fractional flow reserve (FFR), offering reliable functional evaluation of coronary lesions without the need for pressure wires or hyperemic agents.6 Favor III China demonstrated that QFR-guided PCI significantly reduces major adverse cardiovascular events (MACEs) compared to angiography-guided strategies.7 While the prognostic value of post-PCI QFR has been validated in acute settings,8 its role in long-term follow-up—particularly as a surrogate marker for functional completeness of revascularization—remains less well characterized.

Simultaneously, the triglyceride-glucose (TyG) index—a simple surrogate marker of insulin resistance derived from routine fasting lipid and glucose levels—has garnered attention for its predictive capacity in cardiovascular risk stratification.9, 10, 11 Elevated TyG values have been independently associated with higher incidence of CVEs and all-cause mortality across diverse populations.12, 13, 14 Yet, it is unclear how TyG performs in the context of post-PCI patients, especially when stratified by residual ischemia burden as assessed by QFR.

The present study aimed to (1) investigate the prognostic utility of three-vessel QFR (3V-QFR) as a marker of functional revascularization status at one-year follow-up post-PCI; (2) evaluate the association between TyG index and long-term MACEs; and (3) assess whether the predictive value of TyG is modulated by underlying QFR-defined ischemic status. We hypothesized that the TyG index would have differential prognostic value depending on whether physiological revascularization had been achieved, thus supporting a combined functional-metabolic approach to follow-up risk stratification after PCI.