Trial examines the Tryton stent for use in patients with large side branches

A prospective study found that the use of the Tryton side branch stent in patients undergoing PCI was effective in treating coronary artery bifurcations involving large side branches.

The stent is not yet FDA-approved, but Tryton Medical said the company submitted the results of this study and a previous randomized trial to the FDA as part of the company’s premarket approval application.

Lead researcher Philippe Généreux, MD, of the Cardiovascular Research Foundation and NewYork-Presbyterian Hospital/Columbia University Medical Center, and colleagues published their results online in the Journal of the American College of Cardiology: Cardiovascular Interventions on July 4.

The researchers noted that up to 20 percent of coronary lesions treated with PCI are considered as bifurcation lesions. They added that previous research showed that treating bifurcation lesions with PCI was associated with a lower procedural success rate and a higher risk for adverse cardiac events.

Tryton’s randomized trial did not meet its primary endpoint and showed that its bare-metal stent was inferior to balloon angioplasty alone in treating de novo true bifurcation lesions. The researchers said the results were mainly due to an increased incidence of periprocedural MI in the Tryton stent group.

A post-hoc analysis of patients with a side branch diameter of 2.25 mm or more found that patients in the Tryton stent group had better angiographic results and a numeric reduction in target vessel revascularization.

For this analysis, Tryton worked with the FDA to design a study to confirm the results of the randomized study among patients with a side branch diameter of 2.25 mm and confirm the ability of physicians to enroll appropriate patients.

The study included 133 patients with true bifurcation lesions who were treated with Tryton’s bare-metal cobalt chromium thin-strutted side branch stent, which is mounted on a standard stent delivery balloon. All but one patient had a side branch diameter of 2.25 mm. The patients enrolled from July 2014 to July 2015 at 13 sites in the U.S. and 15 sites in Europe.

At baseline, the clinical and angiographic characteristics were similar in this study compared with the previous randomized trial.

Of the patients, 10.5 percent had periprocedural MI, which was numerically lower than in the randomized trial. No patients died during the procedure or within 30 days of the procedure, and the study met its noninferiority primary endpoint.

The researchers cited a few limitations of the study, including that it did not have a randomized design, although they had the same inclusion and exclusion criteria as the previous randomized trial. They also only enrolled patients with lesions that were less than 5 mm and diameter stenoses greater than 50 percent, which could have limited its generalizability to other patient groups.

Further, they did not evaluate the Tryton stent’s cost-effectiveness and did not compare whether the bare metal version of the stent was superior to a drug-eluting version of the Tryton stent. Still, they were confident in their findings.

“In light of the higher procedural success rate, improved acute angiographic results, and higher rate of side branch patency at 9-months compared to provisional stenting, the Tryton Confirmatory Study and the Tryton [randomized trial] support the use of the dedicated bifurcation Tryton stent,” Martin B. Leon, the study’s principal investigator, said in a news release.