Review the entire study, we finally confirmed that : 1) MELD-XI score evaluated at admission were significantly higher in whom with NRP compared to normal flow group. 2) MELD-XI score is a significant independent predictor of NRP in patients with STEMI undergoing PPCI. 3) MELD-XI score had a significant predictive power for for 30-days all-cause mortality in STEMI patients after PPCI. Until then, the predictive role of MELD-XI score in terms of NRP and 30-days all cause mortality in patients with STEMI after PPCI was the first time to study.
The NRP were arising from multiple factors, while the exact mechanism is complex and still unclear. The main viewpoint including spasm or obstruction of the microcirculation, distal microvascular embolization, long ischemic duration, platelet aggregation, oxidative stress, ischemic or reperfusion injury. Studies over the years have shown that NRP remained a powerful independent predictor of early and long-term death in STEMI patients. Patients who NRP developed experiencing major adverse clinical events(MACEs) and complications more frequently than those with normal flow. Therefore, necessary assessment of NRP and short-term risks should be carried out among the patients of candidate PCI to further improve the safety of intervention.
At present, several available biomarkers and easily clinical parameters have been found clear evidence for predicting NRP[13, 14]. The bilirubin is a kind of main bile pigment in human bile and a natural metabolized product of iron porphyrin compounds. The oxidized low-density lipoprotein(oxLDL)-induced ROS production is a harmful cholesterol and a risk factor for atherosclerosis[15, 16]. Several studies demonstrate that bilirubin as a potent endogenous antioxidant to suppress the reactive oxygen species (ROS). Thus, the bilirubin could inhibit the oxidation process of low-density lipoprotein and have a important role in preventing the progression of atherosclerosis via its antioxidant activity. Endothelial dysfunction may be caused by reactive oxygen species produced by oxidative stress. Previous studies have illustrated that endothelial cell damage caused by excessive oxidative stress shown a strong association with NRP in STEMI patients[18, 19, 20]. Celik et al. examined the associations between TB level with NRP and in-hospital major adverse cardiac events. Moreover, they found a tight association between higher bilirubin level with a lower TIMI flow grade and NRP in STEMI patients. This suggests that bilirubin is key mediator to inhibit inflammatory processes especially accompanied by oxidative stress.
Creatinine is anhydride form of creatine. It is proposes as a marker of the renal function. The kidneys’ functional changes can be monitored via the estimation of serum creatinine. Higher serum creatinine at admission is a risk factors of NRP. It has already been demonstrated that mild to moderate renal impairment in STEMI patients underwent PPCI is independently associated with NRP. The exact mechanisms of renal dysfunction and NRP is including the accumulation of elevated reactive oxygen species, inflammatory process and endothelial damage. Endothelial dysfunction was significantly associated with renal dysfunction and impaired myocardial perfusion in STEMI patients. NRP is in part as a result of inflammation-induced reperfusion injury. Several studies found renal dysfunction is also an inflammatory state, while no-reflow phenomenon is associated with inflammatory activity[26–28]. There is a certain correlation between the oxidative stress and NRP, which has been confirmed in previous studys. The generation of oxidative stress also plays a significant role in renal impairment. All these condition probably involved in the development of NRP.
Recently, quite a few studies have also shown that elevated total bilirubin has a good predictive value in the prognosis of acute coronary syndrome (ACS) patients underwent PCI[30, 31]. Previous studies has shown that impaired renal function plays a important role in predicting future MACEs in patients with PCI. Vinod, P. et al shown that patients who had elevated serum creatinine at admission accompanied with increased risk of developing MACEs.
The MELD-XI is a novel and easily-accessible score. It only requires two parameter (TB, sCr) through non-invasive blood test. As a tool to assess liver and kidney function, MELD-XI not only represents the critical condition of patients with organ failure, but is also closely related to in-hospital mortality. Recently,another study demonstrated that the MELD-XI shows good predictive capacity for in-hospital and one-year mortality in older patients with STEMI undergoing PCI. However, the authors did not explore their conclusion could be extrapolated to other age strata. Our results showed patients with higher MELD-XI score have a higher rate of short-term all-cause mortality. We also found MELD-XI score, CK-MB and hs-CRP at admission in multivariate Cox regression were independent predictors for short-term prognosis. Renal and hepatic function may have high predictive power for mortality of cardiovascular disease. Patients with the no-reflow phenomenon are the highest risk subgroup of patients who with increased risks of early and congestive heart failure and of death. The NRP was consistently associated associated with poor prognosis and high mortality rate of STEMI patients after PPCI. Accordingly, our study find the MELD-XI score showed high predictive power for coronary NRP and short-term prognosis, using to early risk stratification of STEMI patients candidate PPCI.
Several important limitations must be considered in our study. First, this is a cross-sectional and retrospective single-center study does not allow causal inference, and with a small sample size, so bias could not be completely ruled out. Second, our clinical samples only from one regions of China, further external validity of results need to be measured. Third, only end-stage liver disease or on dialysis were excluded, patients with previously diagnosed mild to moderate liver and kidney disease will be retained.