It is well known that inflammatory response plays an important role in thrombosis caused by atherosclerotic plaques[16–18]. A large number of studies have shown that inflammation plays an important role in the pathogenesis of STEMI[19], of which lymphocyte has been shown to play a major role in all stages of the atherogenic process[20], that is, lymphocyte impedes the progression of atherosclerosis[21]. At the same time, studies have also shown that inflammation is the main culprit of myocardial ischemia-reperfusion injury in STEMI patients[6, 7]. In STEMI patients, reduced lymphocyte counts were positively associated with the development of MACE[8] and heart failure[22], as well as with poor prognosis [23]. A number of studies related to the prognosis of STEMI patients have shown that a variety of lymphocyte-based inflammatory indicators (such as NLR, PLR, etc.) have a good predictive value for the prognosis of STEMI patients[24–27], among which, a study on in-hospital mortality of STEMI patients found that lymphocyte has a certain predictive value. Its optimal diagnostic value was 1.77mmol/L, sensitivity was 64.4%, and specificity was 50.8%, which was similar to the results of this study[27]. In our study, lymphocyte in the MACE group was significantly lower than that in the non-MACE group, and lymphocyte had a certain predictive value for the occurrence of MACE in hospital, which was consistent with the results of previous studies.
GGT is an important marker of oxidative stress, and the study of Framingham et al. was one of the first epidemiological studies to investigate the relationship between GGT and cardiovascular disease risk, and reported that GGT is a promising marker of cardiovascular disease[28]. Further studies[29–31] have found that serum GGT levels can be used as a biomarker to predict the severity of stenosis in patients with coronary artery disease. A recently published meta-analysis [32] showed that elevated serum GGT levels may be an independent predictor of cardiovascular and all-cause mortality in patients with Coronary heart disease (CHD), and the measurement of GGT can improve the prediction of cardiovascular and all-cause mortality in patients with CHD. A number of studies have proved that GGT level is correlated with the incidence of MACE in STEMI patients undergoing emergency PCI during hospitalization[33], that is, the higher the GGT level, the higher the incidence of MACE in hospital. In addition, studies have shown that GGT can predict the prognosis of STEMI patients within 1 year, and its optimal cut-off value is 29.38U/L, sensitivity is 78.12%, and specificity is 84.15%, which is similar to the results of this study[34]. It seems that GGT levels are associated not only with the development of atherosclerosis, but also with STEMI-related mortality, and GGT has some predictive value in the prognosis of STEMI patients. In this study, the GGT level of patients in the MACE group with poor prognosis was significantly higher than that in the non-MACE group, which is consistent with the conclusions of previous studies. Meanwhile, GGT has certain predictive value for MACE during hospitalization of STEMI patients undergoing emergency PCI.
Many studies have proved that oxidative stress and inflammation play an important role in the occurrence and development of atherosclerosis, and chronic inflammation can also trigger oxidative stress. GGT is involved in oxidative stress and inflammation, while lymphocyte plays an important role in inflammation. Previous studies have shown that increased GGT and decreased lymphocyte are better predictors of outcomes in STEMI patients. GGT/ lymphocyte ratio (GLR), which combines oxidative stress and inflammatory response pathways, seems to have a better prognostic value in STEMI patients than GGT or lymphocyte alone. Recent studies have shown that GLR can be used as a predictor of liver fibrosis, cirrhosis, hepatocellular carcinoma and intrahepatic cholangiocarcinoma[35]. However, at present, there are few studies on GLR in the cardiovascular field at home and abroad. Domestic studies have shown that GLR is related to the complexity of coronary vascular lesions [36]. Another study found that GLR is an independent predictor of MACE occurrence in patients with acute coronary syndrome within 1 year[37]. These results indicate that GLR is correlated with the degree of coronary stenosis, and has a certain predictive value for the prognosis of acute coronary syndrome. However, the prognosis of GLR and STEMI patients has not been studied. In this study, we took whether STEMI patients undergoing emergency PCI had MACE during hospitalization as the outcome, and explored whether there was a correlation and predictive value between GLR and in-hospital MACE. Therefore, we conducted multivariate Logistic regression and ROC statistical analysis, and found that high GLR level was an independent risk factor for in-hospital MACE in acute STEMI patients, and had certain predictive value. ROC analysis showed that the AUC was 76.5%, while the AUC of GGT and lymphocyte were 62.3% and 69.8%, respectively. These results indicate that GLR has better predictive value in hospital prognosis of STEMI patients, and is better than GGT and lymphocyte alone.
This study further found that acute STEMI patients with a history of hypertension who underwent emergency PCI had a higher incidence of in-hospital MACE, but there were no significant differences in gender or age. It is well known that hypertension is a risk factor for cardiovascular disease and cardiovascular-related death[38]. Relevant studies have shown that the increase of circulating neutrophil and the decrease of lymphocyte are closely related to blood pressure regulation and the occurrence of hypertension [39]. In addition, previous studies have reported that oxidative stress plays a key role in the pathogenesis of hypertension and atherosclerosis[40, 41], indicating that oxidative stress may be an independent risk factor for the development of hypertension and atherosclerosis[42], and GGT is also a marker of oxidative stress [43]. GGT may play a key role in the development of high blood pressure. This conclusion was demonstrated in another study, which showed that increased GGT levels increased the risk of hypertension, methionine, and diabetes[44]. Therefore, we speculate that the GGT level in hypertensive patients is higher than that in non-hypertensive patients, and the lymphocyte level is lower than that in non-hypertensive patients. The GLR formula is GGT/ lymphocyte. It has been concluded in this paper that GLR level is correlated with the incidence of in-hospital MACE in STEMI patients after emergency PCI. Meanwhile, increased GLR level increases the risk of hypertension, and hypertension also increases the risk of cardiovascular death. Therefore, increased GLR level in hypertensive patients is more prone to cardiovascular adverse events. It may be because GLR jointly promotes the inflammatory response and oxidative stress process, which is more likely to aggravate the occurrence of MACE.
In summary, GLR is an independent risk factor for the occurrence of in-hospital MACE in acute STEMI patients undergoing emergency PCI, especially in patients with a history of hypertension. Meanwhile, GLR has a good predictive value for the occurrence of in-hospital poor prognosis in acute STEMI patients after emergency PCI. GGT and lymphocyte are easy to obtain and low cost, so it is worth further research to further identify STEMI patients who are at high risk of adverse prognosis. Finally, this study is only a retrospective, single-center study with a small sample size, and the performance and accuracy of the prediction may be affected. Therefore, this finding should be further validated in a multicenter, large sample prospective study.