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A platinum chromium everolimus-eluting stent (EES) is noninferior to a cobalt chromium zotarolimus-eluting stent (ZES) at 1 year in patients undergoing percutaneous coronary intervention (PCI), according to an all-comers study published in the July 1, 2014 issue of the Journal of the American College of Cardiology.  

Similar Rates of Adverse Outcomes

At 12 months, the primary endpoint of target lesion failure (TLF; composite of cardiac death, target vessel-related MI, and TLR) occurred at a similar rate in both stent groups. Patient-oriented clinical outcomes (all-cause death, all-cause MI, and any repeat revascularization) and individual rates of cardiac death, target vessel-related MI, and TLR were also comparable (table 1). 

Table 1. Twelve-Month Events

 Additional analyses found consistent rates of the primary outcome across different subgroups, with the exception of reference vessel diameter (HR 1.58; 95% CI 0.85-2.97; P = .030 for vessels > 2.75 mm vs ≤ 2.75 mm).

ARC-defined definite and probable stent thrombosis occurred in 0.4% of EES patients and 0.7% of ZES patients at 1 year (P = .229). Rates of definite, probable, and possible stent thrombosis and acute, subacute, or late stent thrombosis were also comparable. Additionally, there were no significant interactions between the allocated stent and the allocated antiplatelet therapy regimen with regard to any clinical endpoint including TLF. 

EES demonstrated noninferiority to ZES with an absolute risk difference in TLF of 0% (P = .0247). Neither stent was found to be superior for that endpoint (P = .983). 

Where baseline angiographic data were available and readable (2,471 EES patients and 1,240 ZES patients), longitudinal stent deformation was detected in 7 patients (0.21%) in the EES group but not in the ZES group. Complications occurred while advancing the adjunctive balloon catheter or while withdrawing the trapped intravascular ultrasound catheter, guidewire, or stent, leading to deep engagement of the guiding catheter. In all cases, the proximal part of the stent was affected and the device was substantially shortened. None of these cases, however, led to adverse clinical events. 

‘Keep an Eye Out’ for Stent Deformation

In the roughly 15 months since the results of HOST-ASSURE were presented at the American College of Cardiology’s Scientific Session 2013, the Promus Element and Resolute stents have garnered wide use. In an email, Stephen G. Ellis, MD, of the Cleveland Clinic (Cleveland, OH), told TCTMD that during the first quarter of 2014, Resolute had 30%, Promus had 36%, and the Xience series [Abbott Vascular; Santa Clara, CA] had 34% of the US market share. They all have “very similar track records, although the PLATINUM trial suggested Promus [Element is] slightly better than Xience V,” he explained, noting that the latter device matched Resolute in 2 randomized trials. 

 Dimitrios Karmpaliotis, MD, PhD, of Columbia University Medical Center (New York, NY), told TCTMD in a telephone interview, “For the vast majority of cases these stents can be used interchangeably.”

 The newer platinum-based EES were developed to address structural limitations including strength, recoil, and radio-opacity of the older cobalt chromium-based devices, according to the authors. They point out that longitudinal stent deformation with the EES was a rare occurrence in this study, which is in contrast to at least 2 previous studies that implicated the platinum chromium-based platform as a potential risk factor.   

 Dr. Karmpaliotis added that “though there were no adverse events associated with the stent deformation [at 12 months], we should keep an eye out for this and follow these patients.”

 To correct this issue, in the latest iteration of the Promus stent—the Promus Premier—Boston Scientific “reinforced the ends of the stents to lessen the risk of longitudinal stent compression,” Dr. Ellis reported.

 Low Event Rates Render Results Underpowered    

 An important limitation of this study—noted by the authors and echoed by Dr. Karmpaliotis—is that it was potentially underpowered due to having a lower than expected TLF rate.   

 “This study is underpowered to detect small differences,” Dr. Karmpaliotis said. “However, the event rate was extremely low and this is reassuring for every day practice. Whether the low event rate found in this population applies to every geographic area in the world or all patient populations with different antiplatelet regimens is an open question.”  

 Source: 
Park KW, Kang SH, Kang HJ, et al. A randomized comparison of platinum chromium-based everolimus-eluting stents versus cobalt chromium-based zotarolimus-eluting stents in all-comers receiving percutaneous coronary intervention: HOST-ASSURE (Harmonizing Optimal Strategy for Treatment of Coronary Artery Stenosis–Safety & Effectiveness of Drug-Eluting Stents & Anti-platelet Regimen), a randomized, controlled, noninferiority trial. J Am Coll Cardiol. 2014;63:2805-2816. 

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