Tryton stent safe, but failed to meet primary endpoint

SAN FRANCISCO — A two-stent strategy using the Tryton bare metal stent in coronary bifurcation lesions failed to demonstrate noninferiority to conventional single stenting. However, both approaches appeared to be safe, according to results from the Tryton Birfucation trial.

For the multicenter, international trial, researchers randomly assigned 704 patients with true coronary bifurcation lesions to receive a drug-eluting stent in the main vessel with either a provisional side branch stent (n=349) or the Tryton stent (Tryton Medical Inc.; n=355).

The primary endpoint was a composite of target vessel failure (TVF) including cardiac death, target vessel MI, defined as periprocedural CK-MB elevations greater than three times the normal value, or ischemia-driven target vessel revascularization (TVR) at 9 months post-procedure. A secondary endpoint of side branch in-segment percentage diameter stenosis at 9 months was assessed in a subgroup of 374 patients who received angiographic follow-up.

Martin B. Leon

TVF occurred in 12.8% of patients in the provisional arm and 17.4% of those in the Tryton arm (P=.108). Periprocedural CK-MB elevation was observed in 10.7% of patients in the provisional arm vs. 15.1% of the Tryton arm (P=.109) and clinically driven TVR occurred in 3.6% vs. 4.7% of the provisional and Tryton arms, respectively (P=.564). No cardiac death occurred in either group.

The Tryton stent appeared to improve side branch in-segment percentage diameter stenosis compared with the provisional strategy at 9-month follow-up (31.6% vs. 38.6%; P=.002).

Additionally, in a post-hoc analysis, the Tryton stent demonstrated improved angiographic outcomes in side branches ≥2.25 mm. Side branch in-segment percentage diameter stenosis in the Tryton arm vs. the provisional arm was 30.4% vs. 40.6% (P=.004), with numerically less binary restenosis (22.2% vs. 32.1%; P=.26).

“This is the first major randomized trial with a dedicated bifurcation stent,” researcher Martin B. Leon, MD, professor of medicine at Columbia University College of Physicians and Surgeons and director of the Center for Interventional Vascular Therapy at New York-Presbyterian Hospital/Columbia University Medical Center, said at a press conference. “It’s also the largest randomized trial that’s been done in the field of true bifurcation coronary lesions.

“The Tryton two-stent strategy in true bifurcations … did not meet the noninferiority clinical endpoint as chosen,” Leon said. “However, both strategies were safe; there were rare clinically significant MIs and stent thrombosis rates overall were only 0.4% in this study, and both had low 9-month clinically driven TVR. DES in the main vessel performed well in both arms, [and] Tryton improved side branch percentage diameter stenosis at follow-up.”

For more information:

Leon MB. Plenary session VII: Late breaking clinical trials II. Presented at: TCT 2013; Oct. 27-Nov. 1, 2013, San Francisco.

Disclosure: Tryton Medical Inc. funded the trial. Leon reports receiving research support from Abbott, Boston Scientific and Medtronic.