First Results Presented From Pivotal US Study of the Tryton Side Branch Stent

October 30, 2013—Tryton Medical, Inc. (Durham, NC) announced that the first results from the TRYTON pivotal investigational device exemption (IDE) coronary bifurcation trial of the Tryton side branch stent, a dedicated bifurcation device, were presented during a late-breaking clinical trial session at the TCT 2013: Transcatheter Cardiovascular Therapeutics conference in San Francisco, California. The TRYTON pivotal trial is being conducted under an IDE from the US Food and Drug Administration.

TRYTON is an international, randomized study that compares the Tryton side branch stent to conventional provisional treatment (balloon angioplasty) in the side branch, with both study groups receiving a standard drug-eluting stent (DES) in the main vessel. The study enrolled 704 patients at 67 centers in North America and 11 countries throughout Europe and Israel. The study employed core lab 3D and planar angiographic analysis, as well as intravenous ultrasound analysis.

According to the company, the study found that both the Tryton strategy and the provisional strategy appeared to be safe, with rare clinical postprocedure myocardial infarctions, low rates of stent thrombosis, and no cardiac death. Both the Tryton and provisional arms of the study had low 9-month clinically driven target vessel revascularization (TVR; 4.7% vs 3.6%).

The Tryton device compared to the provisional arm of the study did not meet the noninferiority clinical endpoint of target vessel failure (TVF; 17.4% vs 12.8%); this was largely because of periprocedural CK-MB elevations. Additionally, 60% of the side branch vessels treated were smaller than the intended study population of side branch vessels of ≥ 2.25 mm diameter by qualitative comparative analysis. In this trial, TVF is a composite of cardiac death, target vessel myocardial infarction, and clinically driven TVR.

Tryton compared to provisional treatment demonstrated superiority in reducing percent diameter side branch stenosis (31.6% vs 38.6%; P = .002), which was the powered secondary endpoint.

A post hoc subgroup analysis of the intended study population demonstrated Tryton outperformed the provisional arm of the study in TVF (11.3% vs 15.6%) as well as reduced percent diameter stenosis (30.4% vs 40.6%; P = .004). “The post hoc analysis strongly supports a benefit for the Tryton stent in the intended population. The results are hypothesis generating, to be supported by further analysis,” stated Donald E. Cutlip, MD, in Tryton's press release. Dr. Cutlip is Executive Director of Clinical Investigations at Harvard Clinical Research Institute.

Martin B. Leon, MD, serves as principal investigator of the TRYTON pivotal IDE study. In the company's announcement, Dr. Leon commented, “The pivotal IDE trial is a first of its kind, landmark study that has provided high-quality data and will inform the treatment of bifurcation disease worldwide for years to come. Tryton represents an important option when treating complex bifurcations. I congratulate the study investigators and thank them for their work.” Dr. Leon is Professor of Medicine and Director of the Center for Interventional Vascular Therapy at Columbia University Medical Center and Founder and Chairman Emeritus of the Cardiovascular Research Foundation.

Maciej Lesiak, MD, added, “The findings from the TRYTON IDE trial confirm my personal experience with the Tryton stent over the past 5 years. The Tryton stent enables me to treat high-risk bifurcation lesions in a controlled fashion with superb result. When I'm treating patients with complex bifurcations, the Tryton stent is the preferred treatment option.” Dr. Lesiak, who is Chief of the Catheterization Laboratory at the Karol Marcinkowski University of Medical Sciences in Poznan, Poland, enrolled 37 patients in the Tryton pivotal IDE trial.

According to the company, the Tryton side branch stent system uses the company's Tri-Zone technology to offer a dedicated strategy for treating bifurcation lesions. Tryton's cobalt chromium stent is deployed in the side branch artery using a standard, single-wire, balloon-expandable stent delivery system. A conventional drug-eluting stent is then placed in the main vessel. The stent system has received CE Mark approval and is commercially available in Europe, Russia, and the Middle East. It is approved in the United States for investigational use only.

The company noted that the Tryton stent is supported by clinical evidence in more than 1,000 patients. Published data in a patient-pooled analysis from more than 900 patients treated with the Tryton stent in more than eight European postmarketing registries demonstrated low target lesion revascularization rates of 2.9% at 6 months and 4% at 1 year, and a 0.5% thrombosis rate at 1 year, advised Tryton Medical.