TRYTON Trial Shows Preference Toward Provisional Stenting in Coronary Bifurcation Lesions
In the treatment of non-left true coronary bifurcation lesions, provisional stenting should remain the preferred strategy, according to the results of the TRYTON trial, published Feb. 9 in the Journal of the American College of Cardiology.
Through a prospective, randomized, controlled clinical trial at 58 sites (30 in Europe and 28 in the U.S.), researchers examined 704 patients with bifurcation coronary lesions at baseline and at follow-up after nine months. Patients were randomized into two groups: one received a main vessel stent plus provisional stenting (n=349), while the other received the Tryton Side Branch Stent (n=355), a bifurcation 2-stent strategy used in the treatment of de Novo bifurcation lesions. The primary endpoint for the study was the rate of target vessel failure (TVF) (cardiac death or target vessel myocardial infarction [MI]) and clinically-driven target vessel revascularization. Researchers also evaluated “the side branch in-segment percent diameter stenosis of the bifurcation stent compared with the side branch balloon angioplasty at nine months” as the secondary endpoint.
The results of the trial showed that while reduced stenosis of the side branch of the lesion was seen with the bifurcation stent, that stent did not meet the non-inferiority TVF endpoint when compared with the provisional stent. At follow-up TVF was 17.4 percent in the Tryton group, compared to 12.8 percent in the provisional group, which did not meet the pre-specified non-inferiority margin of 5.5 percent. The researchers note that the difference in primary endpoints is most likely a result of the higher rate of peri-procedural MIs after the bifurcation stent implantation. Researchers, therefore, indicated that provisional stenting should be the preferred primary strategy in the treatment of complex bifurcation lesions.
In a post-hoc evaluation of the inter-core lab variability in quantitative coronary angiography (QCA) analysis of bifurcation lesions also published Feb. 9 in JACC: Interventions, researchers compared the Tryton Side Branch Stent with balloon angioplasty as a side branch treatment. In the original study, the side branch in-segment diameter stenosis was 31.6 percent in the bifurcation stent group, compared to 38.6 percent in the provisional group. Researchers performed the QCA on a sub-cohort of the original TRYTON trial (n=326) at the nine-month follow-up and found that after re-analysis, “the bias of the in-segment percent diameter stenosis of the side branch was reduced to 1.8 percent … [and] there was no longer a difference between both treatment groups.” The authors of the study “emphasize the importance of using the same QCA methodology among different core labs worldwide.”
In an editorial comment, John A. Bittl, MD, FACC, states that on the basis of the TRYTON Trial results, “the flexibility of the provisional stent strategy…with a small protrusion into the main branch in the majority of bifurcation lesions will likely predominate in current practice over an approach using dedicated bifurcation stents…”
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