Feasibility of Orbital Atherectomy System in Calcified Bifurcation Lesion

Coronary artery bifurcation lesion is a common lesion subset in PCI accounting for 15-20% of
the total number of interventions (1). Treatment of coronary artery bifurcation lesions
represents a challenging area in interventional cardiology (2). When compared with
non-bifurcation interventions, bifurcation interventions have a lower rate of procedural
success, higher procedural costs, longer hospitalization and a higher clinical and
angiographic restenosis (3). Factors contributing to this adverse outcome include limitations
of angiography in assessment of side-branch (SB) disease severity and the lack of established
angiographic predictors of SB patency and lumen compromise. Better understanding of the
underlying plaque morphology and plaque composition may facilitate more effective treatment
of bifurcation lesions.

Heavy calcification within coronary atherosclerotic plaque adversely influences both clinical
and procedural success after percutaneous coronary interventions (PCI) (4,5). The use of
drug-eluting stent (DES) in calcified lesions poses special challenges. Atherectomy can
facilitate successful stent delivery and expansion in calcified lesions. Orbital atherectomy
(OA) is the newly FDA approved device for treatment of severely calcified coronary lesions
which works on the principle of elliptical burr movement. The ORBIT I and II clinical trials
evaluated the safety of OA in de novo calcified coronary lesions and demonstrated that
complication rate was comparable to historical controls of rotational atherectomy (6).

Intravascular imaging has provided new understanding of mechanisms associated with SB
compromise following bifurcation PCI (7-9). Plaque shift has been traditionally considered as
the principal mechanism for side-branch compromise after main vessel intervention (9),
however recent intravascular imaging studies have provided new insights by suggesting carina
shift as a major mechanism implicated in side-branch closure (7). Intravascular ultrasound
(IVUS) has been used for guidance in bifurcation lesions, aiding the visualization of plaque
morphology at the main vessel and the side-branches and helping the selection of stent size
and length as well as the selection of stenting strategy. However, due to the low spatial
resolution of IVUS, all attempts for three-dimensional visualization have only focused on
visualization of the luminal contour and not on the vessel morphology or the vessel-stent
interaction. Optical coherence tomography (OCT) has ~10 times higher resolution than IVUS
which allows precise evaluation of the microstructure of the vessel wall including lipid
pool, fibrous cap, calcification, and thrombus (10). In addition, it provides immediate
automated measurements for lumen dimensions before the treatment and precise evaluation of
strut apposition and stent expansion after stenting, which is of particular interest in
bifurcation PCI, since it's been associated with a higher number of malapposed stent struts
and more frequent stent underexpansion leading to higher incidence of stent thrombosis and
restenosis.

OCT has been shown to constitute a valuable tool for PCI guidance and also the utility of
three-dimensional (3D) renderings for assessing the mechanism of side-branch compromise
following intervention in bifurcation lesions. (11,12). The recent development of OCT with
online 3D reconstruction allows the operator to obtain a 3D visualization of the lesion and
may provide a unique tool for guidance during complex bifurcation PCI and potentially improve
stenting results (12). 3D OCT has been used to visualize jailed side branches after
implantation of bioresorbable scaffolds in the main branch and develop a new classification
system based on the number of SB compartments (13). In addition, its potential clinical
application in guiding the rewiring of the distal compartment of the SB ostium (jailed with
stent struts after MB stenting) to minimize the risk of floating struts was demonstrated.

The aim of the study is to analyze the outcomes of main vessel stenting on side branch in
calcified bifurcation lesion and identify preprocedural predictors of side branch
complication by utilizing two-dimensional (2D) and three-dimensional (3D) frequency domain
optical coherence tomography (FD-OCT). Thirty consecutive patients with calcified lesions
requiring PCI of main vessel with drug eluting stent implantation for the treatment of stable
CAD will be included in the study. All potential subjects will sign a separate Mount Sinai
surgical/procedure informed consent for their Cardiac Catheterization procedure on the day of
their hospital visit.

Patients will undergo coronary angiogram. OCT will be performed to analyze plaque morphology,
the extent and location of calcification, side branch size, angle, and ostial involvement.
Patients will undergo PCI with stent implantation according to current standards of care.
Lesion preparation including lesion pre-dilation, and use of atherectomy and protection
devices will be performed at the operator's discretion, followed by MV stenting. The operator
will also decide on length and size of the implanted stent. Procedural optimization, such as
post-dilation or additional stent implantation will be performed based only on the
angiographic findings, according to the discretion of the operator. Coronary angiogram and
another OCT pullback will be performed after PCI.

Inclusion Criteria:

- All patients over 18 years of age presenting with stable coronary artery disease.

- Angiographic lesion with severe calcification with or without side branch (SB) in whom
provisional main vessel stenting strategy is planned after reviewing angiogram will be
recruited

Exclusion Criteria:

- Patients with ostial left main artery lesions or ostial right coronary artery lesions

- Female patients with child bearing potential not taking adequate contraceptives or
currently breastfeeding

- Known allergy to acetylsalicylic acid or clopidogrel.

- Planned surgery within 12 months.

- History of bleeding diathesis

- Major surgery within 15 days

- Life expectancy < 12 months.

- Patients with kidney dysfunction (CrCl<30)