A 9 months follow-up study of the Tryton Side branch Stent, a dedicated bifurcation stent, with optical coherence tomography and 3D quantitative coronary angiography

The treatment of bifurcation lesions is one of the unsolved challenges for
interventional cardiologists. Fifteen to twenty percent of the percutaneous
coronary interventions (PCI) are performed to treat bifurcation lesions.
Patients with bifurcation lesions tend to have more advanced disease and
multiple co-morbidities. Furthermore, bifurcation lesions have been associated
with lower procedural success and a poorer clinical outcome than
non-bifurcation lesions. Therefore new dedicated bifurcation stents are
designed. Some are already on the market, like the Tryton Side Branch stent.
The idea behind its specific design is that it will provide optimal scaffolding
at the carina, with well-apposed struts and also the number of the struts
limited.

This study has the following objectives:
1. To investigate whether stent (mall)apposition is predictive for strut
uncoverage.
2. To investigate the *distribution* of mallapposed struts in both Tryton as
conventional stent.
3. To investigate the correlation between OCT-derived maximal neointimal
hyperplasia thickness and 3D QCA-derived minimal lumen area.

This is a prospective observational study which evaluates stent apposition,
neointimal strut coverage and in-stent restenosis in the new Tryton Side Branch
StentTM after 9 months follow up using optical coherence tomography. All
patients with a bifurcation lesion who are treated with a Tryton Side Branch
Stent in our center are eligible for this study. All these patients are
undergoing nine month follow-up angiography, according to standard clinical
practice for patients with complex lesions. Before angiography, written
informed consent is obtained. In addition to the angiography, OCT is performed
of the stented bifurcation lesion to obtain information about stent apposition,
strut coverage and restenosis. During the angiography we obtain angiographic
views to reconstruct a 3D image of the treated bifurcation lesion.

2 guide wires are introduced: 1 in the side branch and 1 in the main vessel,
which gives a small chance of dissection, like always when guide wires are
introduced in the coronary arteries. The follow up coronary angiography is
extended with 5 minutes. So, the extra radiation burden is limited, the
fluroresence time is prolonged with only 1 minute. With the introduction of two
guidewires, there is always a minimal change for dissection or other
complications which are related to coronary catheterization. For the OCT, 16ml
of extra contrast is used for each vessel.