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Everolimus-eluting stents (EES) yield superior long-term outcomes for the treatment of ST-elevation myocardial infarction (STEMI) when compared to bare-metal stents (BMS), according to 5-year results of the EXAMINATION trial.

The study showed a relative 20% reduction in combined risk of all-cause death, myocardial infarction, and revascularization (21% versus 26% for their BMS counterparts, HR 0.80, 95% confidence interval 0.65-0.98).

EES also reduced 5-year all-cause mortality (9% versus 12% for BMS recipients, P=0.047), noncardiac mortality (2% versus 4%, P=0.027), and target lesion revascularization (4% versus 7%, P=0.012).

"The results of this landmark analysis showed the absence of very late (>1 year) hazards and a benefit of EES compared with BMS over time," , of University Hospital Clinic in Barcelona, Spain, and colleagues reported in the Jan. 23 issue of The Lancet.

When the results were initially presented at the European Society of Cardiology meeting in 2015, Sabaté pointed out in a press release that it was "the first time since primary percutaneous coronary intervention (PCI) demonstrated superiority over thrombolysis that a device (stent) has shown clinical benefit beyond restenosis prevention in a randomised well powered trial in STEMI."

"The benefit of EES in STEMI at long term is reassuring and confirms the use of second-generation stents as the current gold standard treatment in this clinical context," his group concluded in The Lancet.

"Newer drug-eluting stents with thromboresistance properties rightly remain the gold standard in patients with STEMI undergoing PCI, and the most credible benchmark for future trials of metallic or bioresorbable coronary devices," agreed , of Ferrarotto Hospital in Catania, Italy.

In an accompanying editorial, Capodanno noted that EXAMINATION did not produce such favorable results for EES at 1 or 2 years.

"A potential explanation for the lack of benefit was the smaller than anticipated event rate, resulting in low statistical power," he speculated.

The authors wrote that "differences in the patient-oriented endpoint might accrue over a longer period than previously thought, as shown by the results in this study. We found no differences in this endpoint for up to 2 years, but significant differences were noted at 5 years."

EXAMINATION, a multi-center trial performed in Europe, included 1,498 patients who were randomized to receive either EES or BMS before receiving at least 1 year of dual antiplatelet therapy.

The two cohorts shared similar rates of cardiac death (6% for EES versus 7% for BMS, P=0.37), myocardial infarction (5% versus 4%, P=0.35), and definite stent thrombosis (2% versus 2%, P=0.25).

"Overall, the treatment benefit of EES for target lesion revascularisation substantially accrued over the first 12 months but remained sustained over time, which is reassuring because of the absence of a restenosis late catch-up phenomenon," wrote Capodanno.

He added that because "the reduction in definite stent thrombosis initially reported at 1 year (P=0.0183) and 2 years (P=0.03) was no longer significant at 5 years (P=0.25)," the researchers may be looking at "the effect of chance or withdrawal of protection because of cessation of dual antiplatelet therapy."

Sabaté and colleagues acknowledged that "the reduction in all-cause and non-cardiac mortality rates cannot be directly explained." They hypothesized that lesser rates of early stent thrombosis and repeated revascularization "might have improved preservation of the left ventricle ejection fraction, leading to improved long-term outcomes and reduced need for readmission to hospital" -- a major source of infections, which were second only to cancer in causing noncardiac deaths.

The "unanswered questions about the mortality benefit of EES in EXAMINATION emphasise the challenge of event adjudication in clinical trials, and advocate for inclusion of additional specialists other than cardiologists in arbitrating non-cardiac mortality," Capodanno wrote.

The authors warned that "although trial participants might adequately represent the real-world population admitted with STEMI," excluded participants signal that "there are still some patients to whom the reported results do not apply."

In any case, "these results will bring a sigh of relief for physicians who were afraid of a late increase in thrombotic events with newer durable polymer drug-eluting stents in patients with STEMI, as with earlier-generation devices," Capodanno concluded.

From the American Heart Association: