Two Studies Examine Two-Stent Strategy vs. Provisional Stenting in Coronary Bifurcation Lesions

San Francisco, CA—In the NORDIC-BALTIC BIFURCATION IV trial, a two-stent technique showed 6-month rates of MACE comparable to those achieved with provisional stenting. However, in the Tryton Bifurcation study, the two-stent strategy failed to meet the noninferiority endpoint of target vessel failure at 9 months when compared with a single-stent strategy.

The two studies were presented in a late breaking clinical trial session Wednesday at TCT 2013.

For the NORDIC-BALTIC BIFURCATION IV study, Indulis Kumsars, MD, of the Paul Stradins Clinical University Hospital, Latvia, and colleagues randomly assigned 450 patients with either stable or unstable angina or non-STEMI with bifurcation stenoses involving both the main vessel (≥3.0 mm) and side branch (≥2.75 mm) to either provisional stenting (n=221) or a mandatory two-stent technique (n=229). For the study arm, culotte stenting was recommended with t-stenting and mini-crush allowed.

At 6 months, the primary outcome of MACE did not differ significantly between the cohorts (see Figure 1, page 37), nor did any of the individual components. There were no instances of cardiac death in either group.

Procedural and fluoroscopy times were longer and contrast volume was greater for the two-stent technique (P<.0001 for all), but CK-MB release was similar for both procedures. Lesion characteristics were similar between the study arms with the exceptions of longer main vessel reference diameters in the provisional stenting group (P=.04) and longer side-branch lesion lengths in the two-stent group (P<.0001). Only 3.7% of patients assigned to provisional stenting crossed over to side-branch stenting.

“Longer and more complex procedures in the two-stent group did not translate into more procedural MIs,” Kumsars said, adding that longer-term follow-up will help to determine recommendations for an optimal strategy in this lesion subset.

TCT Course Director Gregg W. Stone, MD, of Columbia University Medical Center, New York, N.Y., commented that the study had an “interesting primary endpoint at 6 months, which is kind of in the middle of the clinical restenosis time period. It looks like those curves might be separating.”

Kumsars replied that the angiographic substudy will be completed at 8 months and clinical follow-up will continue through 5 years.

“I’m not sure that I would have interpreted the conclusion in the same way,” said TCT Course Director Martin B. Leon, MD, of Columbia University Medical Center, New York, N.Y. He was surprised by both a “very disciplined” and low crossover rate and the fact that there was no difference in biomarker release between the two arms.

“I don’t know that I would interpret this as being a negative trial for two stents. I’m actually encouraged,” Leon concluded. “I anxiously await the angiographic results.”

Primary noninferiority endpoint not met in Tryton 

For the Tryton Bifurcation trial, Leon and colleagues randomly assigned 704 patients with true coronary bifurcation lesions at 58 international sites to a two-stent strategy (Tryton Medical; n=355) or the accepted provisional single-stent strategy (n=349).

At 9 months, the primary noninferiority endpoint of target vessel failure (composite of cardiac death, target vessel MI or target vessel revascularization) was not met (see Figure 2).

The two-stent approach did, however, meet the secondary superiority endpoint of improvement in percent diameter stenosis of the side branch at 9 months compared with provisional stenting (31.6% vs. 38.6%; P=.002).

In a post-hoc subgroup analysis of the intended study population, the two-stent strategy demonstrated improved clinical and angiographic outcomes in side branches >2.25 mm (41% of enrolled patients), outperforming the provisional arm in TVF (11.3% vs. 15.6%) and in reduction of percent in-segment diameter stenosis (30.4% vs. 40.6%; P=.004).

Of note, the study used the Medina classification for coronary bifurcation lesions. For both groups, more than 99% were interpreted as true bifurcations. When subjected to core lab assessment, the number of true bifurcations dropped to 89.9% in the two-stent arm and 86.2% in the provisional arm.

NORDIC-BALTIC BIFURCATION IV was funded by unrestricted research grants from Abbott Vascular and Cordis.

Kumsars reports no relevant conflicts of interest.

Leon reports receiving grant support/consultant fees and having equity relationships with several pharmaceutical and device manufacturers. 

Stone reports receiving consultant fees and having equity relationships with several pharmaceutical and device manufacturers.