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TRYTON: Bifurcation stenting did not meet primary noninferiority endpoint
Bifurcation stenting is not associated with worse outcomes, but it did not meet the primary noninferiority endpoint of the TRYTON trial.
Target vessel failure rates were similar among patients with bifurcation lesions in the side branch who were treated with dedicated bifurcation stenting and those treated with a main vessel stent plus provisional stenting, but bifurcation stenting did not meet the prespecified noninferiority margin, Philippe Généreux, MD, and colleagues found.
The researchers noted that the most recent evidence indicates that a conservative approach is the optimal strategy for treating de novo bifurcation lesions in the side branch. In the current prospective, single blind, randomized controlled trial, researchers aimed to compare outcomes associated with a dedicated bifurcation stent (Tryton Side Branch Stent, Tryton Medical) with those reported in side branch balloon angioplasty in a cohort of 704 patients culled from 58 centers in Europe and the United States.
Eligible participants were randomly assigned to a bifurcation stent or a main vessel stent plus provisional stenting.
Target vessel failure (TVF) — including cardiac death, target vessel MI and target vessel revascularization — served as the primary outcome measure, powered for noninferiority. In-segment percent diameter stenosis of the side branch at 9 months served as the secondary angiographic outcome measure, powered for superiority.
Results indicated a TVF rate of 17.4% in the bifurcation group and 12.8% in the main vessel plus provisional stenting group (P = .11). Généreux, from Columbia University Medical Center/New York Presbyterian Hospital and the Cardiovascular Research Foundation, and colleagues attributed this increase to more frequent periprocedural MI in the bifurcation group (13.6% vs. 10.1%; P = .19).
The difference in TVF outcomes was +4.6% (2-sided 95% CI, –1 to 10.3; upper limit of the 1-sided 95% CI, 10.3), according to the findings. This failed to reach the 5.5% noninferiority margin that had been prespecified in the study protocols (P = .42 for noninferiority).
Bifurcation stenting yielded a side branch in-segment diameter stenosis rate of 31.6% vs. 38.6% in the provisional group (P = .002 for superiority). Binary restenosis, defined as at least 50% diameter stenosis, at 9 months was 22.6% in the bifurcation arm and 26.8% in the provisional arm (P = .44).
At 9 months, stent thrombosis rates were 0.6% in the bifurcation group vs. 0.3% in the provisional group, whereas mortality rates were 1.2% in both groups (P = 1 for both).
Similar outcomes were reported in participants from the United States and those from Europe.
“On the basis of failure to achieve the noninferiority primary clinical endpoint, provisional stenting should remain the preferred strategy in the treatment of non–left main true coronary bifurcation lesions,” the researchers concluded.
In an accompanying editorial, John A. Bittl, MD, of Munroe Regional Medical Center in Ocala, Florida, wrote that, “On the basis of these results, the flexibility of the provisional T-stent strategy or T-stenting 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 or previous approaches using culotte, crush, or reverse-crush with multiple stents.”
Bittl wrote that a guide size of 6F is recommended for the interventions described in the study. “This allows both the [main branch] and the [side branch] to be wired and fully dilated, if necessary, before jailing the [side branch] wire behind the [main branch] stent,” he wrote. “If the [side branch] requires treatment for flow-limiting dissection or abnormal fractional flow reserve, the distal strut should be chosen for recrossing.
“New approaches that combine drug-eluting technology with flexibility in sizing and conformation—and a minimalist philosophy—are needed to improve the outcomes for bifurcation lesions,” Bittl wrote.
Disclosure: The study was funded by Tryton Medical. Généreux reports receiving speaker fees from Abbott Vascular and consulting for Cardiovascular Systems Inc. Bittl reports no relevant financial disclosures.