CRT: Xience proves safe, effective in small vessels too

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WASHINGTON, D.C.—Everolimus-eluting stents (Xience V, Abbott) at one-year demonstrated safety and effectiveness in a high-risk, real-world small-vessel population, based the post-approval XIENCE V USA study, presented Feb. 28 at the annual Cardiovascular Research Technologies (CRT) conference, where the study was chosen as one of the Best Abstracts.

Improved safety and efficacy of Xience have been previously demonstrated in selected low-risk small-vessel populations in the randomized SPIRIT trials, according to study presenter James B. Hermiller, MD, from St. Vincent Heart Center of Indiana, Indianapolis. “However, these trials included limited data on clinical outcomes in high-risk patients with small-vessel lesions, while small-vessel lesions comprise 30 to 60 percent of PCI procedures in current interventional practices and represent a challenging lesion subset,” he said.

For this study, Hermiller and colleagues sought to evaluate one-year clinical outcomes of more complex XIENCE V USA real-world, small-vessel patients treated with Xience.

Overall, XIENCE V USA is a large, prospective, multicenter, post-approval study designed to examine the safety and effectiveness of Xience in an all-inclusive, consecutive patient population from real-world clinical settings. According to Hermiller, there are no inclusionary or exclusionary criteria beyond informed consent and the use of the stent.

For the study, the primary and co-primary endpoints are:
  • ARC definite/probable stent thrombosis at one year; and
  • The composite rate of cardiac death and MI at one year.

An independent Clinical Events Committee adjudicated all clinical endpoint events (including stent thrombosis, death, MI and revascularization).

Of the total of 4,774 patients included in the small vessel subgroup of XIENCE V USA, 1,869 patients were in the small-vessel cohort with at least one 2.5 mm stent (3,018 lesions) and 2,905 patients were in the non-small-vessel cohort without one 2.5 mm stent (3,602 lesions). Of note, approximately 74 percent of the lesions were treated with one 2.5 mm stent in the small-vessel cohort.

In the small-vessel group, there were more women, more diabetics, more primary PCI, more multivessel disease and a greater history of prior CABG— presenting “an overall sicker group,” said Hermiller. Also, in terms of lesion characteristics, there was more restenosis in the small-vessel group (7.8 vs. 11.3 percent), along with a greater number of chronic total occlusion lesions (3.2 vs. 1.6 percent) and more complex lesions.

For procedural characteristics, the small-vessel cohort had a greater number of lesions (1.6 vs. 1.2), a great number of stents per lesion (1.2 vs. 1.1) and fewer direct stentings (36 vs. 42.2 percent)—the latter of which Hermiller suggests is most likely reflective of the more complex disease state of the small-vessel cohort.

In this large, prospective, real-world study, one-year clinical outcomes from patients implanted with at least one 2.5 mm Xience demonstrated:
  • Stent thrombosis: 1.11 percent (ARC definite/probable), compared with 0.64 percent in the non-small-vessel cohort, which “didn’t reach statistical significance, probably due to power issues.” The rate curve separated at one month and stayed fairly equally separate out to one year.
  • Cardiac death and MI: 6.7 percent, compared with 5.9 percent in the non-small-vessel group (per ARC MI definition; 3.7 percent compared to 2.9 percent in the non-small-vessel group (per WHO MI definition).
  • Target lesion failure: 9 percent, compared with 7.8 percent in the non-small-vessel group (per ARC MI definition; 7.3 percent, compared to 6 percent in the non-small-vessel group (per WHO MI definition)—representing a statistically significant difference.

Despite higher prevalence of risk factors and more complex lesions in the small-vessel cohort, these event rates were comparable in both cohorts, explained Hermiller.

Although a marginally higher target lesion revascularization rate was observed in the small-vessel cohort, the rates remained low in both groups (5.1 vs. 3.9 percent).

These “encouraging results” demonstrate safety and effectiveness of Xience in the high-risk real-world small-vessel population, he concluded.