A Randomized Comparison of a Provisional One-Stent Versus a Dedicated Two-Stent Strategy for True Bifurcation Lesions - TRYTON Bifurcation

Oct 30, 2013
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Author/Summarized by Author:
Anthony A. Bavry, MD, MPH, FACC
Summary Reviewer:
Deepak L. Bhatt, MD, MPH, MBA, FACC
Trial Sponsor:
Tryton Medical
Date Presented:
10/30/2013
Date Published:
02/09/2015
Date Updated:
10/30/2013
Original Posted Date:
10/30/2013
References

Description:

The goal of the trial was to evaluate treatment with a 2-stent strategy compared with a 1-stent strategy for bifurcation lesions.

Contribution to the Literature: This study on bifurcation stenting, shows that a 1-stent strategy with provisional stenting of the side-branch remains the treatment of choice for bifurcation lesions.

Study Design

  • Randomized
  • Parallel

Patient Populations:

  • Patients with objective evidence of myocardial ischemia due to a bifurcation lesion
  • Main vessel required to be between 2.5 and 4.0 mm with lesion ≤28 mm
  • Side-branch required to be between 2.5 and 3.5 mm with lesion ≤5 mm

    Number of enrollees: 704
    Duration of follow-up: 1 year
    Mean patient age: 65 years
    Percentage female: 27%
    Ejection fraction: 58%

Exclusions:

  • ST-segment elevation myocardial infarction (STEMI) within 72 hours
  • Non-STEMI within 7 days
  • Hemodynamic instability
  • Creatinine >2.5 mg/dl
  • Bleeding abnormality
  • Left ventricular ejection fraction <30%
  • Left main lesion
  • Trifurcation lesion
  • Complex lesion including chronic total occlusion, heavy calcium, thrombus, TIMI 0/1 flow, or severe tortuosity

Primary Endpoints:

  • Target vessel at 9 months defined as cardiac death, target vessel MI, or target vessel revascularization

Secondary Endpoints:

  • Percent diameter stenosis of the side-branch

Drug/Procedures Used:

Patients with a bifurcation lesion were randomized to a dedicated side-branch bare-metal stent (Tryton) and a drug-eluting stent in the main vessel (2-stent strategy; n = 355) vs. a drug-eluting stent in the main vessel, plus a provisional stent in the side-branch (1-stent strategy; n = 349).

In the 2-stent strategy, the main-branch and side-branch was pre-dilated, followed by implantation of the dedicated side-branch bare-metal stent from the main-branch into the side-branch, followed by implantation of a drug-eluting stent in the main-branch. Kissing balloon dilatation was the final step.

In the 1-stent strategy, a drug-eluting stent was implanted in the main-branch and the side-branch was intervened upon (balloon or stent) only if poor flow, dissection, or severe residual stenosis. Kissing balloon dilatation was the final final step.

Principal Findings:

Overall, 704 patients were randomized. The mean age was 65 years, 27% were women, 28% had diabetes, 75% presented as stable angina, vessel location was left anterior descending artery in 75%, main vessel reference diameter was 2.9 mm, and side branch reference vessel diameter was 2.2 mm.

In the 2-stent group, an additional side-branch stent was required in 8% of patients; three patients (0.9%) proximally within the side-branch and in seven patients (2.0%) distally within the side-branch. In the 1-stent group, an additional side-branch stent was required in 28 patients (8.0%, p = 0.02 between groups). Procedure time: 70.5 minutes vs. 56.9 minutes (p < 0.001) and contrast volume: 261 vs. 223 cc (p < 0.001), respectively for 2-stent vs. 1-stent strategy.

The primary outcome of target vessel failure occurred in 17.4% of the 2-stent group vs. 12.8% of the 1-stent group (p = 0.11). This exceeded the prespecified margin of noninferiority (p for noninferiority = 0.42). Subjects with a small side-branch (<2.25 mm) did not have benefit from a 2-stent strategy (21.7% vs. 10.3%), while those with larger side-branches (≥2.25 mm) had potential benefit from this approach (11.3% vs. 15.6%, respectively for 2-stent vs. 1-stent; p for interaction = 0.006).

  • Cardiac death: 0 vs. 0, respectively, for 2-stent vs. 1-stent
  • Target vessel MI: 15.1% vs. 10.1% (p = 0.11), respectively
  • In 92% of periprocedural MIs, the creatine kinase-myocardial band was <10 x the upper limit of normal
  • Target vessel revascularization: 4.7% vs. 3.6% (p = 0.56), respectively
  • Stent thrombosis (definite/probable): 0.6% vs. 0.3% (p = 1.0), respectively
  • Side-branch percent diameter stenosis: 31.6% vs. 38.6% (p = 0.002), respectively

Interpretation:

Among patients with a bifurcation lesion, a 2-stent strategy failed to demonstrate noninferiority compared with a 1-stent strategy with provisional treatment of the side-branch. This was due to a higher frequency of periprocedural MI and target vessel revascularization in the 2-stent group vs. the 1-stent group. Angiographic side-branch percent diameter stenosis was lower in the 2-stent group; however, this did not translate into clinical benefit. Bifurcation lesions remain a challenging lesion subset and at the present time, provision stenting of a side-branch remains the preferred treatment strategy. The post-hoc finding of possible benefit from a 2-stent strategy with larger side-branches deserves further study, especially in light of the fact that only 41% of enrolled subjects met the inclusion criteria for side-branch diameter size.

References:

Généreux P, Kumsars I, Lesiak M, et al. A Randomized Trial of a Dedicated Bifurcation Stent Versus Provisional Stenting in the Treatment of Coronary Bifurcation Lesions. J Am Coll Cardiol 2015;65:533-543.

Presented by Dr. Martin B. Leon at the Transcatheter Cardiovascular Therapeutics meeting (TCT 2013), San Francisco, CA, October 30, 2013.

Keywords: Myocardial Infarction, Follow-Up Studies, Angina, Stable, Thrombosis, Drug-Eluting Stents, Creatine Kinase, MB Form, Dilatation, Constriction, Pathologic, Diabetes Mellitus


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