XAMI at 3 Years: Rates of Very Late Stent Thrombosis Similarly Low for EES, SES in Acute MI Patients

In long-term follow-up, a second-generation DES was found to be as safe as a first-generation device with no differences in the rates of adverse events including very late stent thrombosis, according to a study published online January 10, 2015, ahead of print in EuroInterventionTake Home: XAMI at 3 Years: Rates of Very Late Stent Thrombosis Similarly Low for EES, SES in Acute MI Patients

In the main Xience V Stent vs Cypher Stent in Primary PCI for Acute Myocardial Infarction (XAMI) trial, investigators led by Sjoerd H. Hofma, MD, PhD, of the Medical Center Leeuwarden (Leeuwarden, the Netherlands), randomized 625 patients undergoing primary PCI in a roughly 2:1 ratio to receive everolimus-eluting stents (EES; Xience V; Abbott Vascular) or sirolimus-eluting stents (SES; Cypher; Cordis). 

 More than half of patients were treated with radial access, more than 60% had thrombectomy, and the time from first medical contact to balloon inflation averaged 75 minutes. About three-quarters of patients in each group were men, and average age was roughly 62 years. There were no differences between groups with regard to smoking status, diabetes, hypertension, family history of cardiovascular disease, or renal failure.

At 1 year, EES were noninferior to SES with an absolute 3.7% reduction in MACE (cardiac death, nonfatal MI, and TVR), the primary endpoint (RR 0.52; 95% CI 0.27-1.00). Additionally, there were no differences between the 2 stent types in rates of cardiac death, TVR, or Academic Research Consortium–defined definite or probable stent thrombosis. 

The new paper by Dr. Hofma and colleagues looks at 3-year event rates in 620 XAMI patients who were alive at last follow-up. Overall, there were no differences between the EES and the SES groups for MACE, its individual components, all-cause death, or definite/probable stent thrombosis (table 1). 

Table 1. Outcomes at 3 Years

Definite stent thrombosis occurred between years 1 and 3 in 4 EES patients and 1 SES patient (1.0% vs 0.5%; P = .66) for an overall rate of 0.8% in the study population. After 1 year, the vast majority of patients in each stent group were no longer on dual antiplatelet therapy.

The most important findings are “a low cardiac event rate and no significant difference in MACE or any individual endpoint,” Dr. Hofma and colleagues say. They observe that the overall low event rates and the small sample size may have contributed to lack of statistical significance.

Additionally, they note that a comprehensive network meta-analysis of 22 trials involving over 12,000 randomized STEMI patients treated with BMS or first- or second-generation DES found that the first-generation SES performed better than either paclitaxel-eluting stents (PES) or BMS, with a reduction in cardiac death/MI and TVR. For EES, however, data beyond 1year remain limited. “The only dedicated randomized study is the RACES-MI trial, randomizing 500 patients to EES or SES, showing no significant difference in cardiac death, MI, or TVR at 3 years,” Dr. Hofma and colleagues write.

Concern Over Very Late Stent Thrombosis Eased?

The rate of very late stent thrombosis in XAMI is comparable to that of the HORIZONS-AMI trial, which reported a rate of 0.9% for BMS between 1 and 3 years, the study authors note. The SCAAR registry also reported similar rates of very late stent thrombosis for second-generation DES and BMS. But both SCAAR and RACES-MI found an increased risk of very late stent thrombosis with older DES, which was not seen in XAMI. 

Dr. Hofma and colleagues theorize that “higher [GPI] and thrombectomy use in XAMI may have decreased remnant thrombus, possibly reducing early and late stent malapposition. This might play a role in [very late stent thrombosis] and could be more important in thick-strut stents like SES.”

They add that while “fear of increased very late stent thrombosis has limited the use of DES in [MI] patients in recent years,” these 3-year data along with results from other trials “show that the use of second-generation DES, like EES in [acute] MI patients, is highly effective and safe up to at least 3 years of follow-up.”


Source:
Hofma SH, Smits PC, Brouwer J, et al. Long-term follow-up of second-generation everolimus-eluting stents versus first-generation sirolimus-eluting stents in acute myocardial infarction: three-year results of the XAMI trial. EuroIntervention. 2015;Epub ahead of print.

Disclosure:

  • Dr. Hofma reports no relevant conflicts of interest.

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