Superiority of Xience V Over Taxus in Women Sustained at 3 Years

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The superiority of everolimus-eluting stents compared with paclitaxel-eluting stents seen in the overall population of the SPIRIT III trial applies specifically to women and is sustained out to 3 years, according to a subanalysis published online January 24, 2011, ahead of print in the American Journal of Cardiology.

To examine differences in outcomes by gender, researchers led by Alexandra J. Lansky, MD, of the Yale University School of Medicine (New Haven, CT), conducted a post hoc subanalysis of the SPIRIT III (Clinical Trial of the XIENCE V Everolimus Eluting Coronary Stent System) trial.

In the main trial, which randomized 1,002 patients undergoing PCI 2 to 1 to the everolimus-eluting Xience V (n = 669, 30% women; Abbott Vascular, Santa Clara, CA) or the paclitaxel-eluting Taxus (n = 332, 34% women; Boston Scientific, Natick, MA) stent, Xience showed an edge in terms of late loss and 9-month MACE (cardiac death, MI, and TLR) as well as noninferiority with regard to target vessel failure (TVF; cardiac death, MI, or TVR).

Women Fare Worse

In the new analysis, regardless of the stent implanted, women had higher rates of MACE and TLR compared with men at 3 years. However, despite having had a higher 1-year incidence of TVF, by 3 years the rate was equivalent to that of men (table 1).

Table 1. Three-Year Outcomes by Gender

Despite having worse outcomes than men overall, in an analysis comparing the 2 stents in women alone, Xience V fared better than Taxus, as previously reported at 1 year (Lansky AJ, et al. Catheter Cardiovasc Interv. 2009;74:719-727). In the current paper, at both 2- and 3-year follow-up, women treated with the Xience V stent continued to have lower rates of MACE. And although 1-year rates of TVF were similar for the 2 stents, by years 2 and 3 an approximate 40% decrease in TVF emerged favoring Xience V (table 2).

Table 2. Two- and Three-Year Outcomes in Women by Stent

No differences in rates of stent thrombosis or bleeding complications were seen between stent arms throughout follow-up.

Asking the Right Question

The finding that women fared better with Xience V compared with Taxus, and not the fact that women had poorer outcomes than men, is the real take-away message from this analysis, according to Bonnie Weiner, MD, of the University of Massachusetts Medical School (Worcester, MA).

“This trial did what I think is the right analysis. It compared the results of the 2 stents in women themselves and not just against outcomes in men,” Dr. Weiner said in a telephone interview with TCTMD.

“That is a much more powerful statement in the sense of us trying to [understand] whether we should be tailoring therapies differently for women because [treatments may] have a different effect,” she said.

Underpowered Study

The researchers point out that because the study is a post hoc subset analysis, its results must be viewed as only hypothesis generating. They add that the trial was not powered to measure less frequent events such as stent thrombosis, and the results can only be applied to the patient population specified in the trial protocol.

Dr. Weiner agreed. “Although important, this trial really was not powered to show some of the differences between these treatments,” she said. “[Also,] we have to recognize that this is a first-generation stent vs. a more current stent platform.”

In addition, it is unclear whether the observed clinical differences are due to women’s biology or to a differential effect of the stent drugs, Dr. Weiner said, adding, “Until we see comparable devices and studies that are powered to show some of the differences described, it really should not change clinical practice just yet.”

Future trials need to be designed, performed and powered to determine the best therapy for women, she said.

“We need to start looking at some other biologic factors that may be different in women vs. men, including responses to antiplatelet or anticoagulant therapies, age-related changes in hormones, menopausal status, etc.,” Dr. Weiner said. “There is a whole series of things that [researchers] do not measure as part of these trials to try to explain why women respond differently to the same therapies.”

Study Details

Coronary lesions were 28 mm or less in length with a reference vessel diameter of 2.5 to 3.75 mm. All patients received daily dual antiplatelet therapy.

Women were older and had higher rates of hypertension and diabetes than men; however, they had lower rates of prior MI and cardiac interventions. In addition, women had smaller vessel diameters and lower percent diameter stenosis than men. The number of stents per patient and stent length per lesion were similar between men and women.

Note: Coauthor Gregg W. Stone, MD, is a faculty member of the Cardiovascular Research Foundation, which owns and operates TCTMD.

 

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Source:
Ng VG, Lansky AJ, Hermiller JB, et al. Three-year results of safety and efficacy of the everolimus-eluting coronary stent in women (from the SPIRIT III randomized clinical trial). Am J Cardiol. 2011:Epub ahead of print.

 

 

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