TRYTON Study Supports Provisional Approach for Treating Side Branch Bifurcation Lesions

February 9, 2015—Philippe Généreux, MD, et al published results from the TRYTON study in the Journal of the American College of Cardiology (JACC; 2015;65:533–543). TRYTON is a prospective, single-blind, randomized controlled study evaluating the safety and effectiveness of the Tryton side branch stent (Tryton Medical, Inc.) used with a drug-eluting stent to treat de novo bifurcation lesions in the main branch and side branch of native coronary arteries. 

The TRYTON bifurcation trial sought to compare treatment of de novo true bifurcation lesions using a dedicated bifurcation stent or side branch balloon angioplasty. The background of the study is that current evidence for treating bifurcation lesions—which are frequent among patients with symptomatic coronary disease treated by percutaneous coronary intervention—recommends a conservative (provisional) approach when treating the side branch.

The TRYTON investigators concluded that provisional stenting should remain the preferred strategy for treatment of non–left main true coronary bifurcation lesions. 

As summarized in JACC, the investigators randomly assigned patients with true bifurcation lesions to a main vessel stent plus provisional stenting or the bifurcation stent. The primary endpoint (powered for noninferiority) was target vessel failure (TVF; including cardiac death, target vessel myocardial infarction, and target vessel revascularization). The secondary angiographic endpoint (powered for superiority) was in-segment percent diameter stenosis of the side branch at 9 months.

The TRYTON study randomized 704 patients with bifurcation coronary lesions at 58 centers (30 from Europe and 28 from the United States). 

The investigators reported that at 9 months, TVF was 17.4% in the bifurcation stent group compared with 12.8% in the provisional group (P = .11), mainly because of a higher periprocedural myocardial infarction rate (13.6% vs 10.1%; P = .19). The TVF difference of +4.6% (two-sided 95% confidence interval, -1 to 10.3; upper limit of the one-sided 95% confidence interval, 10.3) was not within the prespecified noninferiority margin of 5.5% (P = .42 for noninferiority). 

The side branch in-segment diameter stenosis among the angiographic cohort was lower in the bifurcation stent group compared with the provisional group (31.6% vs 38.6%; P = .002 for superiority), with no difference in binary restenosis rates (diameter stenosis ≥ 50%) at 9 month follow-up (22.6% vs 26.8%; P = .44), reported the TRYTON investigators in JACC.