October 7, 2014

Atherectomy for Peripheral Artery Disease

Endovascular atherectomy has been used for treatment of peripheral artery disease for more than two decades. In that time, there has been a steady rollout

of devices, each equipped with a sexy new moniker.

Atherectomy: Exploring the Evidence

Despite much investment and marketing by a handful of manufacturers, atherectomy has yet to find an evidence-based niche. Though widely accepted for
debulking of calcified lesions to allow full stent expansion, there is considerable debate over the long term patency afforded by a strategy of standalone
atherectomy. Promising competing technologies, such as fracture resistant stents and drug-eluting balloons, have stolen much of the limelight. This is
despite the built-in appeal of performing a procedure where the atheroma is actually removed from the patient, as opposed to pancaked to the vessel’s
intimal surface.

Economic factors may also drive atherectomy use, with reimbursement being substantially higher for femoropopliteal atherectomy ($632.49) than stenting
($518.17), per facility prices on www.cms.gov (accessed July 12, 2013). Though personnel and equipment costs are higher
with atherectomy than stenting, there is still an institutional financial incentive that cannot be ignored (http://www.ncbi.nlm.nih.gov/pubmed/18296016).

Atherectomy lends itself particularly well to common femoral, ostial superficial femoral and popliteal artery intervention, where stenting is unattractive,
especially in patients that are high risk for endarterectomy. Investigations of the use of atherectomy in conjunction with drug-eluting balloons for
lesions across joints are currently underway (http://www.ncbi.nlm.nih.gov/pubmed/23147770).

What, then, could explain the hesitancy to adopt a role for atherectomy? Compared with angioplasty and stenting, atherectomies are longer, more costly and
labor intensive. Given the greater number of moving parts (specialized guidewires, embolic protection etc) involved in the procedure, demonstrating
equivalence of atherectomy to angioplasty or stenting may not be sufficient to justify use. Though there are numerous single center registries reporting
limb salvage rates with atherectomy alone comparable to angioplasty or stenting (75-90%), only three randomized trials have been published:

Shammas et al (2011) compared a strategy of directional atherectomy with adjunctive angioplasty to angioplasty alone in infrainguinal disease ( http://www.ncbi.nlm.nih.gov/pubmed/21757372). At one year, there was no difference in target
lesion revascularization, though atherectomy reduced the need for bailout stenting.

The CALCIUM 360 pilot trial (2012) compared orbital atherectomy plus angioplasty to angioplasty alone in patients with critical limb ischemia ( http://www.ncbi.nlm.nih.gov/pubmed/22891826). Atherectomy was associated with greater procedural
success, less stent utilization and lower target vessel revascularization, though p-values did not reach statistical significance.

Twelve month results of COMPLIANCE 360 show similar rates of target revascularization (and again, lower stent use) with balloon only versus orbital
atherectomy in the femoropopliteal segment ( http://content.onlinejacc.org/article.aspx?articleid=1206286).

These trials have been criticized for qualifying the use of stents as a treatment failure. A stent-avoidant strategy has never been shown to result in
favorable outcomes. In fact, drug-eluting stents may end up as the gold standard for endovascular therapy in the superficial femoral artery. The questions
that need to be addressed in future trials are whether atherectomy with provisional stent placement beats a stenting only strategy and which debulking
device yields the best long term patency. The three categories of atherectomy tools currently approved by the FDA are described below, with examples of
devices from each group.

Directional Atherectomy

Many operators are already familiar with the TurboHawk device (Covidien, Mansfield, MA), which excises bulky, calcified plaque using four contoured blades
and an integrated flushable collection system (http://www.turbohawkdevice.com/About). Recently featured
in the DEFINITIVE LE registry presented by Lawrence Garcia at the VIVA conference in 2012, a multicenter study of 800 subjects with claudication or
critical limb ischemia, TurboHawk atherectomy was established as a safe, effective therapy with one-year patency rates comparable to drug-eluting stents
and balloons (75.4% for SFA, 77.1% for popliteal and 89.6% for infra-popliteal, with lesion lengths of 8.1 cm, 6 cm and 5.5 cm, respectively) (

http://www.turbohawkdevice.com/content/downloads/DEF_LE_12_Mo_VIVA_Garcia_28SEP12.pdf

). Limb salvage at one year in the 201-patient critical limb ischemia subset was an impressive 95%. There were acceptably low rates of distal embolization
(3.8%), flow-limiting dissection (2.3%) or perforation (5.3%).

Clinical Vignette #1

An 81-year-old wheelchair bound gentleman with a history of debilitating stroke, diabetes and hypertension presented with right foot gangrene. There were
dry punctate lesions on all five digits and the first metatarsal. The ankle vessels were not compressible and right toe brachial index was 0.39. Diagnostic
angiography was performed (Fig 1) and the lesion in the right popliteal artery crossed with a 0.035 inch stiff angled Glidewire (Terumo, Somerset, NJ)
supported by a Quick-Cross catheter (Spectranetics, Colorado Springs, CO). TurboHawk atherectomy was performed over a 0.014 inch Grand Slam wire (Abbott
Vascular, Abbott Park, IL); see Fig 2 and 3.

 

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Figure 1.
Right popliteal artery occlusion.

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Figure 2.
TurboHawk atherectomy in the right popliteal artery.

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Figure 3.
Post atherectomy angiogram of the right popliteal artery.

Rotational Atherectomy

The Diamondback orbital atherectomy system (CSI, St Paul, MN) uses an abrasive crown spinning eccentrically around a dedicated guidewire to produce
differential sanding of calcium while sparing the softer vessel wall ( http://www.csi360.com/diamondback360). The device is ideally suited to treating heavily calcified,
angulated lesions and has three different crowns available for select applications. The all-comers CONFIRM registry, containing 3,135 patients undergoing
orbital atherectomy, reported complications of slow flow (4.4%), embolism (2.2%) and spasm (6.3%) were less common when shorter spin times and smaller
crown sizes were used (http://www.ncbi.nlm.nih.gov/pubmed/23737432).

Clinical Vignette #2

A 58-year-old woman with a history of diabetes, cerebrovascular disease and ischemic cardiomyopathy presented with an ulcer on the left great toe. Left
ankle brachial index was 0.58 and pulses were absent in the posterior tibial and monophasic in the dorsalis pedis arteries. Diagnostic angiography was
performed (Fig 4, 5) and the lesion in the SFA was crossed with a 0.014 inch PT2 moderate support wire (Boston Scientific, Quincy, MA) supported by a
Quick-Cross catheter. Following dilatation with a 4×120 mm balloon, Diamondback atherectomy was performed in three runs with a 2.25 mm burr. Self-expanding
stents (6×150 mm and 6×80 mm) were placed and post-dilated (6×100 mm); see Fig 6 and 7. Distal atheroembolization (Fig 8) was treated with intra-arterial
alteplase (Fig 9).

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Figure 4.
Proximal left superficial femoral artery occlusion.

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Figure 5.
Reconstitution at the adductor hiatus, with patent left popliteal artery.

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Figure 6.
Post atherectomy and stenting in the left superficial femoral artery.

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Figure 7.
Post atherectomy result in the distal left superficial femoral artery.

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Figure 8.
Atheroemboli in the left tibioperoneal trunk.

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Figure 9.
Left tibioperoneal trunk post lytics.

Excimer Laser Atherectomy

Though atheroablative laser technology has been used in the peripheral arteries for well over a decade, many operators are less familiar with current
iterations like the CVX-300 (Spectranetics, Colorado Springs, CO). Registry data is relatively scant compared to other modalities. However, results of the
EXCITE ISR trial, designed to show a potential novel role for laser in treatment of restenosis, are eagerly anticipated (http://www.spectranetics.com/patients/pad-peripheral-artery-disease/clinical-trial-enrollment). As angioplasty is obligatory after laser atherectomy, there is a possible niche for this device in combination with drug-eluting balloons below the
knee.

Conclusion

Procedural cost, operator unfamiliarity and a lack of randomized comparisons with newer modalities (i.e. stenting) have hindered the widespread use of atherectomy. Many labs keep an atherectomy device on the shelf for tackling lesions that are not dilatable, and it can be an elegant solution when seeking to avoid stent placement in the common femoral or popliteal arteries. Importantly, endovascular atherectomy has not been compared to open endarterectomy in these vessels (CFA, popliteal artery). Registry studies have established the safety and efficacy of atherectomy, but carefully constructed trials will be needed to elucidate where these devices stand amongst the other new players vying for a spot in the peripheral interventionalist’s armamentarium.