Hemoglobin glycation index and prognosis after successful chronic total occlusion percutaneous coronary intervention: a retrospective cohort study

Background: Even after technically successful percutaneous coronary intervention (PCI) for chronic total occlusion (CTO), patients face persistent excess cardiovascular risk. The hemoglobin glycation index (HGI), a marker of interindividual glycation heterogeneity, has not been studied in this setting. Methods: We enrolled 1, 513 patients who had undergone successful CTO-PCI between 2011 and 2023 at Guangdong Provincial People's Hospital. HGI was computed as the difference between the measured HbA1c and the value predicted from fasting plasma glucose using a cohort-derived linear equation. The primary composite outcome included cardiovascular death, non-fatal myocardial infarction, and stroke (cardiovascular events, CVEs). Secondary outcomes were all-cause and cardiovascular death. Multivariable Cox regression and restricted cubic splines were applied to assess associations. Results: During a median 810-day follow-up, 83 (5.5%) all-cause deaths, 53 (3.5%) cardiovascular deaths, and 73 (4.8%) CVEs occurred. After full adjustment, Each 1-standard deviation increment in HGI conferred an independent hazard of 1.34 (95% CI 1.14-1.58) for all-cause mortality, 1.52 (95% CI 1.25-1.83) for cardiovascular mortality, and 1.42 (95% CI 1.15-1.61) for CVEs. Compared with the lowest tertile, patients in the highest HGI tertile exhibited a 2.41-fold (95% CI 1.37-4.25, P = 0.002), 4.13-fold (95% CI 1.91-8.94, P<0.001), and 2.73-fold (95% CI 1.47-5.07, P = 0.001) higher risk of all-cause mortality, cardiovascular mortality, and CVEs, respectively. RCS analysis revealed a linear dose-response relationship, with a secondary exploratory threshold effect identified at HGI = -0.15 for CVEs (HR 2.05, 95% CI 1.22-3.44). Conclusions: In this retrospective cohort study, elevated HGI was independently and linearly associated with heightened long-term adverse clinical outcomes after successful CTO-PCI. These findings suggest that HGI may have potential as a prognostic marker for risk stratification in this population; however, prospective validation is required before clinical application.