Abstract: Peripheral arterial disease (PAD) is a clinical manifestation of systemic atherosclerosis and is associated with significant morbidity and mortality. The physiological force and shear stress from angioplasty and stenting have made PAD treatment challenging. Atherectomy devices have continued to emerge as a major therapy in the management of peripheral vascular disease. This article presents a review of the current literature for the atherectomy devices used in PAD.
J INVASIVE CARDIOL 2017;29(4):135-144.
Key words: atherosclerosis, atherectomy, peripheral vascular disease
Peripheral arterial disease (PAD) is a clinical manifestation of systemic atherosclerosis and is associated with significant morbidity and mortality. An estimated 12 to 15 million Americans suffer from PAD.1 Many can present with symptoms ranging from mild pain on exertion to rest pain, progressive ulceration, frank tissue loss, or gangrene. Therapy is dictated by the stage and severity of disease, and may include medical therapy, percutaneous endovascular interventions, open surgical bypass procedures,2 or any combination of the above.
PAD varies in nature, severity, distribution, anatomy, and biophysics. Despite the advances in our understanding of this complex disease, a durable treatment strategy and “gold standard” for all comers is still lacking.3-5 Specifically for the lower limb, stents have overall better durability compared with simple balloon angioplasty in PAD, but for longer lesions (more than 10 cm) and heavily calcified lesions in the superficial femoral artery (SFA) no single device has evolved as the default gold standard.6
Stents or permanent devices over joint spaces and other highly constrained segments have the risk of stent cell/strut fracture and ultimately may lead to stent failure. These challenges make the prospect of not leaving behind permanent implants in the vessel potentially a more attractive therapeutic option. Atherectomy has emerged as a viable option for the treatment of PAD in the infrainguinal space.
Definition of atherectomy. Atherectomy refers to the endovascular removal of atheromatous tissue by cutting, shaving, drilling, or pulverization by sanding, resulting in enlargement of the treated lumen. Atherectomy devices are classified into the following four categories based upon the mechanism of action: excisional or directional atherectomy (DA); orbital atherectomy (OA); atheroablative atherectomy; and rotational atherectomy.
DA refers to the active removal of plaque from arterial walls in a controlled and directional fashion whereby the plaque removed is directly captured in the nose cone or other receptacle. In the United States, Medtronic/Covidien offers the SilverHawk, TurboHawk, HawkOne, and optical coherence tomography (OCT)-guided Avinger-Pantheris DA devices, which are currently Food and Drug Administration (FDA)-approved for use in PAD.
The SilverHawk, approved by the FDA in 2003, is a new-generation device with a conical cutter that engages plaque, and spins at 8000-16,000 rpm. The original SilverHawk device has one conical blade in the cutter, and has been developed into various forms of different catheters: TurboHawk, which now has four inner blades/bars thus allowing more engagement and plaque removal per pass; RockHawk, which possesses an extra burr on the rotating blade to treat heavily calcified lesions; and HawkOne, which has 50% higher cutter speed and ability to treat both soft and calcified plaque. The blade is housed in the device, which engages the plaque at variable heights via a hinge system that deflects the rotating blade away from the center of the vessel toward the target plaque. There are 17 different catheters available in the SilverHawk family and a specific catheter can be employed depending on the vessel size (1.5-7 mm) and lesion length, make-up, or composition (Table 1).
Most of the catheters are designated by two or three letters. The first letter refers to vessel size (ie, L = large; M = medium; S = small; E = extra small); the second letter refers to the length of nose cone (ie, S = standard length; X = extended length); and the third letter refers to the variation in the design (ie, M = presence of microefficient compression [MEC] technology; and C = special modification for use in calcified lesions). These catheters require different sheath sizes (Table 1) and a non-specialized 0.014˝ guidewire (usually extra-support wire). Some of the newer TurboHawk devices have a longer nose cone with MEC technology. MEC technology provides laser-cut microholes in the wall of the storage segment of the nose cone. These microholes release fluid and retain the tissue, which leads to an increased tissue capturing capacity. This technology increases the insertion time and decreases the number of reinsertions to empty the nose cone.
The SilverHawk device consists of two components, a low-profile catheter and a hand-held drive/control unit; both are disposable (Figure 1). The atheroma is excised longitudinally and is collected and stored in the nose cone, which is located distal to the cutter window. Depending on the length of nose cone and amount of atheroma excised, multiple passes can be made before the nose cone requires emptying, which can be monitored by the location of plunger under fluoroscopy (Figure 2).
Zeller et al have demonstrated the feasibility and safety of the new DA device in infrainguinal disease.7 Earlier reported clinical experience with SilverHawk atherectomy have shown inconsistent rates in the primary patency (PP), including the TALON (Treating Peripherals with SilverHawk: Outcomes Collection) registry. The PP varied from 54%-84% in native vessels with de novo intervention.8-12 The TALON registry, which examined SilverHawk with adjunctive angioplasty (26.7%) and stenting (6.3%), was the first large non-core lab adjudicated registry that reported PP of 80% at 1 year.9,10
DEFINITIVE-LE (Determination of Effectiveness of the SilverHawk Peripheral Plaque Excision System [SilverHawk Device] for the Treatment of Infrainguinal Vessels/Lower Extremities) was a 47-center prospective trial that investigated DA in 800 subjects (both claudicants and critical limb ischemia [CLI]) with infrainguinal disease. The 12-month overall primary patency was 78% in claudicants (95% confidence interval [CI], 74%-81%). The rate of freedom from major unplanned amputation of the target limb at 12 months in CLI subjects was 95% (CI, 90.7%-97.4%). Periprocedural adverse events included embolization (3.8%), perforation (5.3%), and abrupt closure (2.0%). The bail-out stent rate was 3.2% (Table 2).13
Safety and efficacy of DA was established in diabetics (53%) enrolled in DEFINITIVE LE.14 A comparable 12-month PP (77.0% vs 77.9%; superiority P=.98; non-inferiority P<.001) and freedom from target-lesion revascularization (TLR; 83.8% vs 87.5%; P=.19) was noted in both diabetic and non-diabetic patients, respectively. Unfortunately, the role of distal embolic protection wasn’t established. Distal embolization was noted in 30 of the 799-patient cohort (3.8%), of which only 1.6% underwent additional intervention during the primary procedure.13 DEFINITIVE Ca established both efficacy and safety of DA device along with distal embolic protection (SpiderFX) in 133 subjects with moderate to severely calcified lesions in the superficial femoral and/or popliteal arteries. The overall 30-day freedom from major adverse event (MAE) rate was 93.1%.15
The Pantheris device, FDA approved since October 2015, is a first-of-its-kind lumivascular atherectomy catheter. It is an 8 Fr-compatible device with a 130 cm working length and uses a non-dedicated 0.014˝ guidewire. It provides real-time imaging using OCT while the catheter is being used. By combining DA with real-time OCT, plaque is removed while avoiding injury to the normal arterial wall structures or deep wall structures such as adventitia, thus potentially improving safety and durability. As the evidence is growing in favor of adventitial injury as a possible risk for restenosis post DA, the inability to see the actual plaque when using two-dimensional angiography is a real concern.
The VISION (Evaluation of the Pantheris Optical Coherence Tomography Imaging Atherectomy System for Use in the Peripheral Vasculature) trial was a prospective, single-arm, non-randomized, global, investigational device exemption (IDE) trial. The primary cohort included 130 patients (164 lesions; mean age, 67 years), of which 125 patients completed the 6-month follow-up. Preliminary results showed a high primary efficacy (96.3% with ≤50% postprocedure stenosis) and safety (MAE rate, 17.6%).16 The reported MAEs were TLR (8%), cardiovascular death (3.2%), myocardial infarction (2.4%), amputation (0%), and device-related events (4%). Bail-out stenting was 4.3% (n = 7 lesions).
DA and in-stent restenosis. Trentmann et al demonstrated that the SilverHawk device could be first-line treatment for in-stent restenosis of the femoropopliteal artery. They demonstrated treatment success (<50% residual stenosis) of 86% with atherectomy alone, while success increased to 97% with additional PTA (43%). Despite the procedural success, target-lesion patency fell drastically from 86.2% at 3 months to 25% at 12 months.17 Thus, the theoretical advantage of debulking the hyperplasia did not result in prevention of recurrent hyperplasia.
In a recent retrospective analysis, both SilverHawk atherectomy and excimer laser ablation (ELA) used after simple angioplasty continued to have a high TLR rate in femoropopliteal in-stent restenosis.18 A higher rate of delayed failure was seen with SilverHawk and an earlier, steeper loss of TLR-free survival was seen with ELA.18 The pathophysiology underlying restenosis post DA with stents and in de novo lesions remains elusive. Tarricone et al compared the histopathological analysis of atherectomy specimen in 116 patients with claudication or Trans-Atlantic Intersociety Consensus (TASC) A/B lesions in the superficial femoral or popliteal arteries. The primary endpoint was the duplex-documented 1-year rate of restenosis, which was determined by a peak systolic velocity ratio <2.4. The overall 1-year incidence of restenosis was 57%, but the rate was significantly higher (P<.001) in patients with adventitial or medial injury (60/62; 97%) vs those without (6/54; 11%).19
DA and drug-coated balloons. With the advent of drug-coated balloon (DCB) technology, directional excisional atherectomy offers a theoretical complementary role by improving tissue delivery of drug into the media and improving the compliance of the vessel, making it favorable to balloon angioplasty, thus avoiding the need for stenting. Leaving no residual stent hardware might be the preferred therapy in “no-stent” zones of femoral and popliteal bifurcations.
In a single-center experience, Cioppa et al demonstrated the safety and efficacy of a combined endovascular approach using DA + DCB for the treatment of heavy calcified lesions of the femoropopliteal tract in 30 patients. Procedural and clinical success was achieved in all cases, with a bail-out of only 6.5%. At 12-month follow-up, limb salvage rate was 100% and TLR rate was 10%.20 Sixt et al also showed that DA + DCB did better in restenotic lesions (primarily in-stent restenosis) vs DA + PTA. In their experience, 1-year freedom from restenosis rates in the DCB and PTA groups were 84.7% and 43.8%, respectively.21
DEFINITIVE-AR (Directional Atherectomy Followed by a PacliItaxel-Coated Balloon to Inhibit Restenosis and Maintain Vessel Patency), a prospective, multicenter, randomized pilot study, was designed to assess the effect of treating a lesion with DA followed by a paclitaxel-coated balloon (DAART) vs a paclitaxel-coated balloon alone. One-year data of 121 subjects enrolled at 10 investigational sites was presented at VIVA 2014. Overall higher technical success was achieved in DAART, with lower incidence of flow-limiting dissection thus requiring no bail-out stenting. The 12-month angiographic patency (primary outcome) was 82.4% in DAART vs 71.8% with DCB only. Added benefit was observed in the DAART group if lesion length was ≥10 cm (90.9% vs 68.8%)or severely calcified (70.4% vs 62.5%) (Table 2).22
The REALITY study plans to evaluate the adjunctive use of DA and DCB treatment of patients with symptomatic PAD in long, calcified SFA and/or popliteal artery lesions. This trial will be a multicenter, prospective, single-arm, observational, angiographic and duplex ultrasound, core-lab adjudicated study that will enroll 250 patients at up to 20 sites across the United States. Medtronic’s DA systems (HawkOne, TurboHawk, and SilverHawk) and its In.Pact Admiral DCB will be studied. Similarly, the ADCAT (Atherectomy and Drug-Coated Balloon Angioplasty in Treatment of Long Infrapopliteal Lesions) study will enroll 80 patients with CLI (Rutherford class 3-6) to be treated with TurboHawk and paclitaxel DCB.
How to optimize DA in PAD. For most lesions, retrograde access is the most uniformly used strategy for revascularization. Appropriate sheath size should be selected (Table 1). The most common sheath size for the larger device is 7 Fr, with 6 Fr being used for the smaller DS cutters. Lesion selection is best in vessels that first can accommodate the device for the larger devices (>5 mm) and in the smaller devices (>2 mm). Lesions with significant soft plaque are considered the best lesions for DA. Even though special DA devices are made for calcified lesions, it may have less benefit for heavily calcified lesions that may not allow the cutter to fully engage the lesions, but rather pass along the top of the lesion in crossing them. In these lesion types, a distal protection filter device is required to capture the distal embolic debris that may become inherently liberated in these calcified lesions. The Spider filter device has been FDA indicated for use with the SilverHawk in calcified lesions.
Once a lesion is identified as potentially a target for DA, the best technique for treatment remains serial passes of the device in various planes (generally 4-8 quadrants) to fully “excise” the area. Understanding that the minimum lumen diameter of the lesion is driven by the surrounding reference diameter leads to the best outcome (possibility of achieving a ≤30% residual stenosis following DA). This may be obtained with continued DA passes or with the aid of adjunctive PTA.
The principal outcome of patency is best obtained from optimal atherectomy with or without adjunctive angioplasty or stenting. The complications seen in DEFINITIVE LE (perforation, 5.7%; distal embolization, 3.5%) do suggest that the careful selection of patients and lesions for therapy is critical to have the best outcomes using DA. Technical know-how of the level of nose cone filling is critical so as to not overfill the device, thereby allowing for atheromatous plaques to not be captured at the time the cutter is disengaged from the atheroma. This is done by watching where the cutter comes to rest when it is advanced into the nose cone. This inherent fill gauge allows one to know when to remove the device for emptying.
The Diamondback Orbital Atherectomy System (Cardiovascular Systems, Inc) is FDA approved for OA. It employs a diamond-coated crown that rotates 360° in an eccentric manner, thereby engaging plaque and not engaging normal tissue. All debris generated in its ablation is considered small (smaller than a red cell in the vast majority of particulates [>99%]). It is designed to modify the surface of calcified plaques by preferentially cutting or sanding the atheroma plaque while avoiding the elastic arterial wall. Current versions include the Predator 360° and the Stealth 360° PAD system with three different crown types (Table 3). The device consists of a catheter with a control handle and a console, which is the source of pneumatic power (Figure 3). A dedicated 0.014˝ wire (ViperWire) is used together with a continuous infusion of a coolant mixture of saline and Rota-glide lubricant to avoid thermal injury to the vessel wall.
OA has been shown to be both safe and effective in femoropopliteal and infrapopliteal segments. The OASIS (Orbital Atherectomy System for the Treatment of Peripheral Vascular Stenosis) study was the pivotal trial for approval of the device. This trial was a non-randomized IDE study of 124 patients (201 stenoses) with infrapopliteal arterial occlusive disease. The 30-day (2.3%) and 6-month (10.4%) MAE (death, myocardial infarction, amputation, or repeat revascularization) were low, while procedural success (final diameter stenosis ≤30%) was high (90%). Adjunctive therapy was needed in 41% of the cases and consisted of PTA (39.3%) and stenting (2.5%). Stand-alone atherectomy was performed in 116 lesions (57.4%).23
Patients with PAD who were treated with OA were followed in large, multicenter, non-randomized, all-comer registries (CONFIRM I, II, and III).24 Different CSI devices were evaluated: CONFIRM, Diamondback 360° (n = 733 subjects and 1146 lesions); CONFIRM II (Predator 360°, n = 1127 subjects and 1734 lesions); and CONFIRM III, Diamondback 360°, Predator360°, and Stealth360° (n = 1275 subjects and 1886 lesions). The CONFIRM series, devoid of inclusion or exclusion criteria, treated 4766 lesions in 3135 enrolled patients. Severely calcified lesions were easily removed compared with soft plaque. OA with adjunct treatment with low-pressure balloon inflation (5.4-5.9 atm) or provisional stenting were 73.3% and 5.7%, respectively. Compared with other studies, the complication rate was low (dissection, 11.3%; slow-flow, 4.4%; embolism, 2.2%; and perforation, 0.7%). This suggests embolic protection is not needed; however, these event rates are non-core lab driven endpoints and investigator-reported alone.
In two small randomized pilot studies (CALCIUM 360 and COMPLIANCE 360),25,26 OA + PTA was shown to have a lower incidence of complications and bail-out stenting, and greater freedom from TLR compared with PTA alone in femoropopliteal and infrapopliteal lesions. In the TRUTH study, the pre-OA and post-OA visual histology-intravascular ultrasound analyses confirmed that OA modifies the calcium in lesions, thus improving procedural success with low-pressure adjunctive balloon angioplasty.27 Preliminary 30-day data from the LIBERTY-360 registry showed positive outcomes irrespective of the severity of PAD.28 Liberty 360 is a prospective, observational, multicenter clinical study to evaluate the clinical and economic outcomes of a variety of endovascular interventions in patients with symptomatic PAD including CLI. The 30-day freedom from MAE rates were 99% (Rutherford 2-3), 95.7% (Rutherford 4-5), and 90.7% (Rutherford 6). More than two-thirds of patients were treated with Diamondback 360° OA (45% in Rutherford 2-5 and 60% in Rutherford 6) (Table 4).
Excimer Laser Atherectomy
Excimer laser atherectomy (Spectranetics) uses ultraviolet laser light to debulk or dissolve atherosclerotic plaque. The 308 nm excimer laser delivers short bursts (125 ns) of energy leading to “photoablation” of the plaque without damaging the surrounding tissue. This ablation is photochemical and photomechanical rather than photothermal, and generates subcellular debris (90% of which are <10 microns).
The device consists of a variably sized fiber-optic catheter (2.7-7.5 Fr) and a central console (Figure 4), and has been approved for use in infrainguinal arterial de novo stenosis, restenosis, and chronic total occlusions that have not been crossed with a guidewire. Multiple catheters are currently available: Turbo-Power, Turbo-Booster, and Turbo-Tandem for above-the-knee arteries, and the Turbo-Elite for smaller arteries above and below the knee (Table 5).
The PELA (Peripheral Excimer Laser Angioplasty) trial was one of the earliest trials to review this technology. It compared laser-assisted PTA to PTA alone in 251 patients of SFA-CTOs longer than 10 cm. There was no difference between the groups in terms of technical success, patency, or need for reintervention at 12 months.29 The Laser Angioplasty for Critical Limb Ischemic (LACI) prospective, multicenter trial reviewed 145 patients with 155 critically ischemic limbs who were poor candidates for bypass surgery. Success rates for delivery of laser treatment (99%) and balloon angioplasty (90%) were high. A 6-month limb salvage rate of 92% among survivors was achieved and only 2% of LACI patients required surgical revascularization.30 At long-term (2-year) follow-up, when compared with PTA alone, laser therapy + PTA was associated with a significantly lower TLR rate (14% vs 44%; P=.05) in class I/II femoropoliteal in-stent restenosis and lower rate of recurrent stenosis in class III femoropopliteal in-stent restenosis (69% vs 100%; P=.05).31The CELLO (CliRpath Excimer Laser System to Enlarge Lumen Openings) study, a single-arm prospective registry, demonstrated safety and efficacy of the newer-generation Turbo-Booster/Turbo-Elite laser catheters for SFA and proximal popliteal disease. There were no MAEs. One-year primary patency and freedom from TLR rates were 54% and 76.9%, respectively.32
The EXCITE (EXCImer Laser Randomized Controlled Study for Treatment of FemoropopliTEal In-Stent Restenosis) trial led to the FDA approval of laser atherectomy for the treatment of femoropopliteal in-stent restenosis. This prospective, multicenter trial randomized Rutherford class 1-4 patients to excimer laser atherectomy + PTA or PTA alone by a 2:1 ratio.33 Excimer laser atherectomy + PTA achieved superior procedural success (93.5% vs 82.7%; P=.01) with significantly lower 30-day MAE rates (5.8% vs 20.5%; P<.001) and a 52% reduction in TLR (hazard ratio, 0.48; 95% CI, 0.31-0.74) compared with PTA alone (Table 4).
The potential benefit in management of SFA in-stent restenosis of laser debulking followed by DCB angioplasty vs DCB alone was studied in a small, single-center, prospective, randomized study.34 Compared with DCB alone, laser debulking + DCB was demonstrated to have a higher 1-year patency (66.7% vs 37.5%; P=.01) and TLR rate (16.7% vs 50%; P=.01). PHOTOPAC (Photoablative Atherectomy Followed by a Paclitaxel-Coated Balloon to Inhibit Restenosis in In-Stent Femoropopliteal Obstructions), a large, prospective, randomized, two-arm study, is underway to compare the safety and efficacy of laser debulking + DCB with DCB alone.
Rotational atherectomy devices have high-speed rotating cutting blades that lead to differential cutting of the atheroma while preserving the elastic tissue wall of the uninvolved vessel. Approved devices include the Rotablator system (Boston Scientific/Scimed), Pathway Jetstream PV atherectomy system (Boston Scientific), and the Phoenix atherectomy catheter (Volcano Corporation).
The Pathway PV atherectomy system was FDA approved in 2008 for the atherectomy of infrainguinal vessels and thrombectomy of upper-extremity and lower-extremity vessels. The tip of the system contains five expandable rotating blades along with an aspiration function for the preemptive removal of scraped plaque. This is the only atherectomy system with active aspiration. The 1.6 and 1.85 Jetstream SC atherectomy catheters are currently available to treat infrapopliteal lesions, while the 2.1-3.0 and 2.4-3.4 Jetstream XC atherectomy catheters are designed for superficial femoral artery-popliteal lesions (Figure 5, Table 6).
The Pathway PVD trial was a multicenter study of 172 patients with 210 femoropopliteal and infrapopliteal lesions over 1 year.35 The mean lesion length was relatively small (2.7 cm) and one-half of lesions (51%) had a moderate-to-high calcium score, while one-third (31%) were CTOs. Clinically driven 1-year TLR rate was 26%, and the clinical benefit in infrainguinal arteries was found to be similar between diabetics and non-diabetics. Treatment of 40 infrainguinal in-stent restenoses with the Pathway device followed by PTA showed 1-year and 2-year PP rates of 33% and 24%, respectively (Table 4).36
The Jetstream system has been demonstrated to significantly increase the luminal area and volume, as determined by virtual histology ultrasound, in severely calcified femoropopliteal lesions.37,38 The treatment of femoropopliteal in-stent restenosis with the JetStream atherectomy device is associated with a high procedure success (91%) and a low need for bailout stenting (6.3%).39 Embolic filter protection was used in one-half of the cohort and macrodebris were noted in 12%, with a small number of the limbs (9.4%) requiring treatment for distal embolization. Freedom from TLR at 6 and 12 months (not including intraprocedural bailout stenting) was 86% and 59%, respectively. Patency (duplex-derived peak systolic velocity ratio <2.4 at 6 months) was 72%, and no new stent fractures or deformities were observed at 6 months.
The FDA-approved Phoenix Atherectomy System is an over-the wire system that comprises a double-lumen catheter with a distal metal cutting element and a handle. When activated (by sliding the ON and OFF on the handle), the distal tip rotates and in the process shaves plaque, which is dislodged into the catheter. The minimum vessel diameter is 2.5, with catheter sizes down to 1.8 mm in diameter with a 5 Fr profile (Table 6). The Phoenix system was investigated in the EASE (Endovascular Atherectomy Safety and Effectiveness) study. This prospective, single-arm, multicenter, FDA-approved IDE studied the effectiveness and safety of the device in 105 patients (communication from Atheromed, Inc). Acute technical success (residual diameter stenosis ≤50%) was achieved in 95.1% and primary safety rate (30 days free from MAE) was 94.3%.
Inherently, simple balloon angioplasty has not been functional as a default therapy for the lower limb due to its inconsistencies from lesion to lesion and lack of significant durability in longer lesions. Similarly, the presence of heavy calcification reduces the vessel compliance, making it vulnerable to suboptimal angioplasty and/or significant differential expansion potentially leading to significant dissections. Placement of intravascular prostheses, ie, bare-metal or drug-eluting stents, has proven better than PTA alone in the lower limb without exception. The principal limitation with stenting is the process of in-stent restenosis. Once encountered, it appears to return again despite further PTA. Alternative therapies with a “leave nothing behind” approach such as with DA have been shown to be safe and effective in various infrainguinal anatomic locations. Despite the absence of direct head-to-head comparison with any other devices, and with those devices versus any other devices, the outcomes at 1 year are very similar and comparable with other stent trials in the SFA location, but long-term outcome data (beyond 1 year) are lacking in DA. Although the role of DA in in-stent restenosis is not well established, DA combined with drug-coated balloon may have some benefit, especially in calcified and longer lesions.
We need to understand more about pathogenesis of neointimal hyperplasia post DA and possible patient and procedural risk factors associated with it. Recent evidence suggests deeper cuts leading to adventitial injury can be a risk factor for neointimal hyperplasia. This association needs to be further studied and new techniques and technology need to be devised to minimize adventitial injury. Potential live image guidance during atherectomy (as with the Pantheris catheter) may minimize the cutting of non-atheromatous vessel wall, provide better control over the depth of the excision thus avoiding adventitial injury, and lead to fewer complications. But these promising hypotheses need to be confirmed with both randomized studies as well as large registries.
Atherectomy devices have continued to emerge as a major therapy in the management of peripheral vascular disease.
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From the Division of Vascular Medicine, St. Elizabeth’s Medical Center, Tufts University School of Medicine, Boston, Massachusetts.
Disclosure: The authors have completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. Dr Garcia is the founder of Innovation Vascular Partners; he reports non-financial support from Boston Scientific, Abbott, and Medtronic and is an equity holder in CV Ingenuity, TissueGen, Arsenal, Primacea, Sytervention, Essential Medical, Scion Cardiovascular, and Spirox. The remaining authors report no conflicts of interest regarding the content herein.
Manuscript submitted November 1, 2016 and accepted November 16, 2016.
Address for correspondence: Lawrence A. Garcia, MD, Division of Interventional Cardiology and Vascular Medicine, St Elizabeth Medical Center/Tufts University School of Medicine, 736 Cambridge Street, Brighton, MA 02135. Email: Lawrence.Garcia@steward.org