SPIRIT III: Evaluation of the XIENCE V Everolimus-Eluting Stent -- Clinical, Angiographic, and IVUS Results

Luis Gruberg, MD, FACC

Disclosures

April 27, 2007

  Presenter: Gregg W. Stone, MD (Columbia University Medical Center, New York, NY), on Behalf of the SPIRIT III Investigators

The XIENCE V drug-eluting stent system (Abbott, Abbott Park, Illinois) releases everolimus from a thin cobalt-chromium stent strut covered by a durable biocompatible fluoropolymer. The SPIRIT II trial found that the XIENCE V stent had a significantly lower late loss compared with the TAXUS paclitaxel-eluting stent (Boston Scientific, Natick, Massachusetts).

The SPIRIT III trial was designed as the US pivotal approval study for the XIENCE V stent.

Study Design

A total of 1002 patients were enrolled at 65 centers in the United States. Patients with a reference vessel diameter ≥ 2.5 mm and ≤ 3.75 mm and a lesion length ≤ 28 mm were randomized in a 2:1 fashion to either the XIENCE V stent (n = 669) or the TAXUS stent (n = 333). Patients were treated with dual antiplatelet therapy for at least 6 months. The study was designed to show noninferiority and superiority. Angiographic follow-up was obtained in 77% of patients.

Primary endpoint: In-segment late loss at 8 months.

Secondary endpoints: Ischemia-driven target vessel failure defined as cardiac death, myocardial infarction, and vessel revascularization at 9 months.

Results

Baseline clinical characteristics are shown in Table 1 , and baseline lesion characteristics are shown in Table 2 .

The primary endpoint of the study -- late loss at 8-month angiographic follow-up -- was 0.28 ± 0.48 mm in the TAXUS arm and 0.14 ± 0.41 mm in the XIENCE V stent, which met both the noninferiority (P < .0001) and superiority (P = .004) endpoints. Binary restenosis rates were lower in the XIENCE V stent group, although the difference did not achieve statistical significance (Figure).

Figure.

SPIRIT III: binary restenosis at 8-month follow-up.

At 9-month clinical follow-up, the rates of target vessel failure, each of its individual components, and the rate of major adverse cardiac events were lower in patients treated with the XIENCE V stent ( Table 3 ). Stent thrombosis at 270 days was rare in both groups, and the rate of all-cause mortality was also low ( Table 3 ).

Conclusions

  1. The everolimus-eluting XIENCE V stent was both noninferior and superior to the TAXUS paclitaxel-eluting stent in reducing in-segment late loss (primary endpoint).

  2. The XIENCE V stent significantly reduced in-stent late loss at 8 months and reduced angiographic follow-up diameter stenosis with a strong trend toward lower binary restenosis.

  3. The XIENCE V stent demonstrated noninferior rates of target vessel failure at 9 months, with a significant 44% reduction in major adverse cardiovascular events. It also showed a strong trend toward reduced ischemia-driven target lesion revascularization, with a significant reduction in any target lesion revascularization.

Viewpoint

The results of SPIRIT III, which will be used to seek US market approval of the XIENCE V stent showed that the stent has minimal late loss, which was reflected by the low rates of restenosis and target lesion revascularization. Unfortunately, a large number of patients did not undergo angiographic follow-up. The clinical outcome of patients was very good, although the study was not powered to detect a significant difference in these endpoints. The low rates of stent thrombosis will need to be addressed during the long-term follow-up of these patients.

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