In-stent restenosis (ISR) is the Achilles’ heel of percutaneous coronary intervention (PCI). A common cause of ISR is an under-expanded stent secondary to under preparation of a target vessel with circumferential deep calcification. ISR management is challenging and there are several treatment modalities currently available, including drug-eluting stents/balloons, cutting/scoring balloons, atherectomy, and intravascular brachytherapy.1-4 Orbital atherectomy (Cardiovascular Systems, Inc. [CSI]) has limited evidence in the management of ISR.5 A recent retrospective series of 41 patients with undilatable under-expanded stents demonstrated a 98% success rate for orbital atherectomy with a 5% rate of periprocedural myocardial infarction/Ellis type II coronary perforation.5 We describe a case of orbital atherectomy crown entrapment during atherectomy of multilayer in-stent restenosis, resulting in segmental stent explantation.
A 77-year-old male with history of coronary artery disease status post multiple coronary interventions to the right coronary artery (RCA) with 2 layers of stent in the proximal, mid and distal vessel, brachytherapy of the proximal RCA 26 months prior, hypertension, and diabetes mellitus (type 2) presented for left heart catheterization due to recurrent Canadian Cardiovascular Society III angina. Diagnostic angiography was performed via the right radial access (7 French sheath [Terumo], Launcher 3D right guide catheter [Medtronic]) and demonstrated severe ISR within 2 layers of stent extending from the proximal RCA to the mid-distal transition (Figure 1). Optical coherence tomography (OCT) of the RCA had been performed during a prior intervention (Figure 2). We wired the distal RCA with a ViperWire Advance Peripheral Guide Wire with Flex Tip (CSI) and performed orbital atherectomy at low speed in the proximal RCA with significant crown-vessel interaction at point A (noted on Figure 1). During orbital atherectomy, it took approximately 20 seconds to cross the “lesion”. We then performed orbital atherectomy with the same device at high speed with significant difficulty in advancing the crown past point A. At this time, the crown stalled in the right coronary artery and the crown could no longer be retracted into the guide catheter. Manual tension was applied on the equipment to free the crown from the vessel, with the resultant disengagement of the guide and wire from the RCA. At this time, we removed the CSI crown from the body, re-engaged the guide catheter, and advanced a workhorse wire into the distal RCA without difficulty. Further examination of the CSI crown revealed entrapment of the crown within a fragment of stent, with avulsed tissue (presumed neointimal proliferation material) attached (Figure 3).
The patient reported severe chest discomfort at this time. Electrocardiography did not reveal any evidence of ST changes. Angiography revealed a linear opacity in the proximal RCA at the site of crown interaction that was presumed to be the site of stent fracture/extraction (Figure 4, red arrow), without evidence of coronary perforation and preserved Thrombolysis in Myocardial Infarction (TIMI) 3 flow in the vessel. Given the absence of perforation, we predilated the ISR segment with a 3 x 20 mm non-compliant balloon at 16 atmospheres (atm) throughout. OCT using a Dragonfly catheter (Abbott Vascular) demonstrated an area of red thrombus formation at the site of stent extraction (Figure 5). Persistent ISR material was also noted to be diffusely spread throughout the proximal and mid RCA. We then proceeded with pre-dilating the vessel with a 3.5 x 10 mm Wolverine balloon (Boston Scientific) at 12 atm, followed by a 3.5 x 20 mm NC Emerge balloon (Boston Scientific) at 20 atm. Repeat OCT imaging demonstrated persistent ISR material in the mid RCA, and the vessel was subsequently dilated with a 3.5 x 15 mm NC Emerge balloon at 20 atm. We performed intravascular brachytherapy, covering the segment of ISR extending from the proximal RCA into the mid-distal transition. Final angiography demonstrated 20% residual stenosis in the vessel with TIMI-3 flow in the distal vessel, and no evidence of dissection or perforation (Figure 6). The patient had an uneventful post-procedural course and was discharged from the hospital after overnight observation.
To the best of our knowledge, this the first case of stent disruption resulting from the use of orbital atherectomy. A case has been reported previously of an unwound device as a result of stent interaction where the wire was inserted behind a stent strut.6 It was hypothesized to have occurred as a result of the inherent nature of the device, comprised of a sanding disc (made of twisted, supportive wires) and coiled wires, features that provide radial strength and elasticity. Upon stretching of the device, spaces can develop and result in stent strut and device interaction. Our case is unique, as the OCT pre-orbital atherectomy demonstrated the wire being free in the lumen of the vessel rather than behind a stent strut. Caution should be taken at high speed (120,000 revolutions per minute) and 1 mm/sec advancement rate, as this allows the crown to create a larger orbit of around 2.0 mm and increases interaction with the stent. Intravascular imaging using intravascular ultrasound or OCT is particularly helpful in assessing the lumen/stent diameters and avoiding wiring under stent struts. The main aim of using rotational/orbital atherectomy in the management of ISR is debulking the ISR, as well as the underlying calcific/fibrotic plaque. Diameters and wire position derived from intravascular imaging can assist in preventing such complications.
Disclosures: The authors report no conflicts of interest regarding the content herein.
The authors can be contacted via Jaikirshan J. Khatri, MD, at email@example.com
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