This study was designed to compare the 12-month clinical outcomes among ZES, SES, and PES in acute MI patients with CKD. Multivariate analyses and Cox regression models showed that ZES was associated with a higher incidence of MACE than SES, and a higher rate of TLR than SES and PES.
In patients with acute MI, primary PCI with stent implantation is considered to be the gold standard in treatment for acute MI [1
]. Although PCI with stent implantation is performed in increasing numbers of patients, in-stent restenosis is an important complication. Studies of patients with acute MI treated with BMS have reported the incidence of repeated revascularization to be about 10% [2
]. Most suggested that DES was associated with a lower restenosis and TLR rate compared with BMS [2
]. The data reported here support the use of DES in acute MI since the TLR rate for all types of DES was 2.1%.
CKD patients are known to be a high-risk population for coronary artery disease. Cardiovascular events, especially related to coronary artery disease, remain the main cause of mortality among patients with CKD [9
]. Furthermore, the presence of CKD increases the risk of mortality after PCI even before end-stage renal disease and dialysis dependency have developed [20
]. In support of this, an eGFR < 30 mL/min/1.73 m2
in the current study was a significant independent predictor of MACE, MI, or death after 12 months.
A concern following DES implantation in acute MI patients is that vessel healing at the primary pathological site is delayed compared with in stable angina patients, which results in an increased risk of thrombotic complications [5
]. ZES, which is second-generation DES and is based on a different type of polymer, is closer to BMS than first-generation DES. ZES implantation is associated with less inflammation and greater endothelialization [8
], and preserved endothelial vasomotor response compared with first-generation DES [7
]. The clinical outcomes of ZES treatment in acute MI patients are not significantly different than those of first-generation DES [21
], and the use of ZES results in a lower risk of stent thrombosis [21
]. In patients with CKD, DES significantly reduces clinical, angiographic restenosis compared with BMS [11
], but there is no data comparing the different types of DES. In this study, we have determined that ZES promotes vessel healing and endothelial function compared to first-generation DES in acute MI. However, excessive neointimal proliferation might increase the TLR rate of ZES patients compared with first-generation DES. When taken together, particularly in acute MI patients who have CKD as comorbid disease, the disadvantages of ZES may outweigh the advantages. In fact, the present data demonstrate that the higher incidence of MACE in the ZES group, as compared with the SES and PES groups, is due mainly to a higher incidence of TLR and not to death or MI. However, TLR rates were around 2% and much lower than before, even though ZES was statistically inferior to the other stents in terms of TLR. Thus, the biological applicability of this result remains to be established.
This is the first study based on observational registry data. We used Cox regression analysis to correct for confounding factors, but the results may be influenced by the nonrandomized assignment. Additionally, this registry does not record information concerning hemodialysis, so it was not possible to separate hemodialysis from non-hemodialysis patients. Recent studies have also shown that DES may be associated with increased rates of stent thrombosis, as compared with BMS [24
]. Unfortunately, in this registry, data concerning the rates of stent thrombosis were not available. As a consequence, it was not possible to assess one of the most important safety markers. Finally, we compared both first- and second-generation DES. However, the ZES in this study was not the Endeavor Resolute Stent (Medtronic Vascular) but the Endeavor Sprint Stent (Medtronic Vascular). Since some studies have already demonstrated that new-generation DES might be safer and more effective than earlier-generation types, further evaluations of new-generation DES are urgently needed.
In conclusion, our data suggest that ZES is inferior to SES and PES in terms of 12-month TLR, and has a higher incidence of MACE. The latter is due mainly to the higher TLR rate compared with SES in acute MI patients with CKD.