Effect of high-sensitivity C-reactive protein on the relationship between haemoglobin A1c and cardiovascular events in patients with acute coronary syndrome undergoing percutaneous coronary intervention: a cohort study

BACKGROUND: There are different opinions on haemoglobin A1c (HbA1c) in predicting cardiovascular events after percutaneous coronary intervention (PCI). Some factors may affect the ability of HbA1c to predict cardiovascular events, resulting in this inconsistency. Inflammation is a direct and whole-process participant in atherosclerosis. However, no one has studied the effect of inflammation on the correlation between HbA1c and cardiovascular events. Therefore, we aimed to test the hypothesis that high-sensitivity C-reactive protein (hsCRP) modulates HbA1c-related cardiovascular events in patients with the acute coronary syndrome (ACS) undergoing PCI. METHODS: This was a retrospective cohort study. We enrolled patients with ACS who were hospitalized for PCI and followed up for 24 months. The primary outcome was the composite of major adverse cardiovascular and cerebrovascular events (MACCEs), including all-cause death, nonfatal myocardial infarction, nonfatal stroke, and unplanned repeat revascularization. We stratified the overall population by HbA1c tertiles and hsCRP median. The relationship between HbA1c, hsCRP, and cardiovascular events was analysed by the Cox proportional hazard regression model. RESULTS: A total of 2,023 patients were enrolled in this study (age: 59.7±10.03 years old, 78.1% male patients). After the 24-month follow-up, 152 (7.51%) events occurred. Patients with hsCRP >1.21 mg/L had an increased cardiovascular risk compared with patients with hsCRP ≤1.21 mg/L [hazard ratio (HR) 1.58, 95% confidence interval (CI): 1.12–2.24, P=0.010]. We did not observe a significant correlation between HbA1c and cardiovascular events. Furthermore, we stratified patients by hsCRP ≤1.21 or >1.21 mg/L and found that the correlation between HbA1c and cardiovascular events was only significant in patients with hsCRP ≤1.21 mg/L (tertile 2 vs. tertile 1: HR 1.76, 95% CI: 0.79–3.90, P=0.165, tertile 3 vs. tertile 1: HR 3.03, 95% CI: 1.50–6.12, P=0.002; P=0.008 for trend) but not in patients with hsCRP >1.21 mg/L. CONCLUSIONS: This study showed that hsCRP may affect the relationship between HbA1c and the risk of cardiovascular events in patients with ACS after PCI. This finding suggests that the risk of cardiovascular events may be underestimated when only HbA1c is used as a predictor of cardiovascular risk. HbA1c has a better predictive value in the absence or low levels of inflammation states represented by hsCRP as a predictor of cardiovascular events.