Abstract
BACKGROUND: The prognostic value of coronary artery bypass grafting (CABG) may be suboptimal when guided solely by anatomical stenosis severity. Quantitative flow ratio (QFR), a computational angiography-derived hemodynamic assessment tool, offers functional insights; however, its prognostic interplay with lesion localization [proximal vs. mid-to-distal left anterior descending artery (LAD)] remains unclear. This study evaluates the impact of QFR-guided revascularization, stratified by LAD lesion location, on midterm clinical outcomes. METHODS: A retrospective cohort of 481 patients undergoing left internal mammary artery (LIMA) to LAD grafting (2019-2023) was analyzed. Lesions were classified as proximal (Site 1) or mid-to-distal (Site 2) LAD and stratified by QFR thresholds (High: ≥0.80; Low: <0.80). The primary endpoint was 5-year major adverse cardiovascular and cerebrovascular events (MACCEs), assessed using Kaplan-Meier survival analysis and Cox regression. RESULTS: High QFR patients (n = 139) exhibited lower diabetes (28.1% vs. 40.6%, p = 0.013), smoking rates (27.3% vs. 38.6%, p = 0.025), and 3-vessel disease (48.9% vs. 74.6%, p < 0.0001) compared to low QFR (n = 342). Proximal lesions with high QFR had markedly higher MACCEs risk (HR = 1.91, 95% CI: 1.18-3.10; Log-rank P = 0.0075), whereas mid-to-distal lesions showed no QFR-driven prognostic differences (p = 0.46). Lesion location alone did not independently influence survival (Log-rank P = 0.8). CONCLUSION: QFR-guided risk stratification is most prognostically impactful for proximal LAD lesions, where hemodynamic significance plays a critical role in clinical outcomes. In contrast, mid-to-distal lesions exhibit limited QFR utility, emphasizing anatomical-functional synergy in CABG planning. Despite comparable survival across lesion sites, proximal low QFR lesions warrant intensified surveillance.