The key role of inflammation in diseases development has attracted more attention, and the studies on inflammatory indices have been highlighted in recent years. At present, hs-CRP and CRP are widely used as indicators of inflammation. Although both the two indices are actually measured with C-reactive protein, the clinical significance of CRP and hs-CRP is not exactly the same[17, 18]. CRP has good performance in the diagnosis of infectious and connective tissue diseases, whereas, hs-CRP, due to its higher sensitivity, precision and reproducibility, seems better for diagnosis of cardio-and cerebrovascular disease[14, 18–20]. Contrary to other specific inflammatory factors or markers, the hs-CRP and serum albumin are easily measured in clinics, and are widely used in many primary hospitals, with a high penetration rate, stable results and easy to observation. Through the combination of the two indicators above, HCAR has the advantages of simplicity, low-cost and high reliability. On the basis of making full use of the existing biochemical examination, HCAR can help to excavate more detailed diagnosis and treatment information, provide reference for clinical diagnosis and treatment, and effectively save costs, which is potentially valuable in clinical application.
Previous studies have suggested that coronary atherosclerosis is a multistep and chronic inflammatory process. Inflammation plays a key role in the formation, development and rupture of atherosclerotic plaques. In 2019, Zhuang conducted a randomized clinical trial, enrolling 3802 subjects followed up for 5.01 years, and it was found that hs-CRP was positively associated with the incidence of coronary heart disease in the general population. In 2014, Daniel's study identified hs-CRP as an independent predictive factor of 30-day mortality in STEMI patients. Serum albumin level can reflect the nutritional status of patients and predict prognosis of cancer, infection and critical patients. A low albumin level indicates poor prognosis of patients. Therefore, by combining hs-CRP and albumin, the predictive value of HCAR has gained increasing attention of researchers. Wang et al. have shown that HCAR is closely related to the incidence of short-term adverse cardiovascular events in patients with acute coronary syndrome, and could provide help to risk stratification. However, the clinical value of HCAR in AMI patients has not been reported, especially in patients with chronic kidney disease.
Using scatter diagrams and correlation analysis, this study showed that HCAR was significantly and positively correlated with inflammatory indices, leukocyte count and hs-CRP, in AMI patients with CKD undergoing CAG. Thus, HCAR is a useful indicator closely related to hs-CRP, which could also reflect inflammation. Besides, HCAR was positively correlated with NT proBNP, CK MB, TnI, AST and ALT, and negatively correlated with LVEF and eGFR (P < 0.05). These findings indicate that HCAR is significantly associated with cardiac, renal and hepatic functions. Thus, in patients with AMI combined with CKD, HCAR may reflect the severity of myocardial infarction, as well as cardiac and renal function.
The current study also showed that in AMI patients with CKD undergoing CAG, HCAR has a good value in predicting mortality. The diagnostic efficiency is the highest when HCAR is 0.24, with a sensitivity of 66.2% and specificity of 52.0%. Therefore, in this study, the patients were divided into two groups with the HCAR value of 0.24 as the cut-off value. Consistent with the above correlation analysis, the group with a higher HCAR was negatively correlated with eGFR, and positively correlated with NT-proBNP, CK MB, TnI, ALT and AST, which further confirmed that HCAR has certain advantages in reflecting the severity of myocardial infarction, as well as cardiac and renal function. Especially, a negative correlation between HCAR level and mortality was observed, suggesting that HCAR may predict prognosis of the patients. Further analysis of survival rates of patients showed that the survival time of patients in the group with a lower HCAR was significantly longer than that in the group with a higher HCAR. Hence, a comprehensive analysis of mortality risk factors was conducted. The Cox survival analysis indicated that higher HCAR level, older age and higher NT-proBNP were independent predictors of 2-year mortality of AMI patients with CKD undergoing CAG.
Also, there was a negative correlation between HCAR and eGFR (P < 0.05). The predictive value of HCAR in CKD patients was also investigated. The results showed that HCAR had a good diagnostic value in predicting the severity of CKD. HCAR was most efficient in the diagnosis of CKD staging when HCAR was 0.17, with a sensitivity of 77.6% and specificity of 39.7%. These results indicate that HCAR is clinically valuable in evaluating the renal function of AMI patients with CKD undergoing CAG.
However, this study also has some limitations. Firstly, this was a retrospective and single-center study with a limited sample size. Thus, a prospective, multicenter and randomized controlled trial is required to corroborate our findings. Secondly, this study only focused on value of HCAR in predicting the 2-year mortality of AMI patients with CKD undergoing CAG. Further studies need to be conducted on MACE, CKD progression and mortality in 5years or even longer time. Thirdly, this study only evaluated the association of HCAR level with prognosis of the patients upon admission, lacking the data reflecting changes over time. In the future, more information should be collected to gain more insight into the diagnostic value of HCAR.
In conclusion, this study indicates that HCAR may comprehensively reflect the condition of AMI patients with CKD undergoing CAG. HCAR could not only reflect the degree of inflammation, but also predict the severity of myocardial infarction, renal function, liver function and prognosis. With its advantages of simplicity, cost-effectiveness, and reliability, HCAR is potentially applied clinically in the future.