Safety and Feasibility of the Coronary Orbital Atherectomy System via the Transradial Approach

Abstract: Technological innovations have enabled higher success rates with percutaneous coronary intervention (PCI) of complex coronary lesions via the transradial approach. The orbital atherectomy system (OAS; Cardiovascular Systems, Inc) is the most recent innovation that abrades plaque using a rotation device for the facilitation of stent placement in heavily calcified lesions. Fifty patients with classic anginal symptoms and an abnormal stress test demonstrating ischemia underwent PCI using the coronary OAS. In all, 46 out of 50 patients received stents in the target lesion after orbital atherectomy. At follow-up, there were no major adverse cardiovascular events, including cardiac death, myocardial infarction, and need for target-vessel revascularization. Radial artery occlusion rate was 6% at 30 days. The use of the OAS via the radial approach may be a safe and feasible option to assist in the treatment of heavily calcified coronary lesions. 

J INVASIVE CARDIOL 2015;27(11):E252-E255

Key words: orbital atherectomy, transradial intervention, new technique

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Technological innovations have enabled higher success rates with percutaneous coronary intervention (PCI) of complex coronary lesions via the transradial approach. However, heavily calcified coronary lesions continue to be a challenge. These complex calcified lesions can decrease procedural success by affecting stent deliverability,¹ increasing balloon rupture,² and/or resulting in the underexpansion of stents.³ Suboptimally expanded stents increase the likelihood of stent thrombosis and restenosis,^4,5 and in turn, will result in a higher rate of target-vessel revascularization.⁶ As a result, many heavily calcified lesions are considered high risk for PCI and treated with coronary artery bypass graft surgery instead.⁷ However, the development of atherectomy devices has enabled the percutaneous treatment of these lesions. The orbital atherectomy system (OAS; Cardiovascular Systems, Inc) is an innovation that abrades plaque to facilitate stent placement in heavily calcified lesions. Given the difficulty in the percutaneous treatment of calcified coronary lesions, especially via the transradial approach, there is a need to evaluate the feasibility and safety of the orbital atherectomy device.

Methods

From June 2014 to September 2014, a total of 50 out of 451 patients undergoing PCI during this period underwent PCI using the coronary OAS. All 50 patients presented with classic anginal symptoms and an abnormal stress test demonstrating ischemia. The coronary OAS is indicated to facilitate stent delivery in patients with coronary artery disease (CAD) who are acceptable candidates for percutaneous transluminal coronary angioplasty or stenting due to de novo, severely calcified coronary artery lesions in the absence of thrombus or significant dissection.⁸ Arterial access was obtained with a 6 Fr Glidesheath Slender (Terumo Corporation) in the right or left radial artery using a standard double-wall puncture technique. The operators involved in this study perform >300 transradial PCIs/year. All patients received an intraarterial cocktail with 100 µg nitroglycerin and 2.5 mg verapamil. A severely calcified coronary artery lesion was identified by angiography at the discretion of the individual operator. This was based on the presence of severe calcium deposits at the lesion site with angiographic evidence of radioopacities noted without cardiac motion prior to contrast injection involving both sides of the arterial wall in at least one location, as well as a total calcium length of at least 15 mm that extended partially into the target lesion. Once a severely calcified coronary artery lesion was identified, and an interventional treatment option was chosen, the procedure was performed per our standard lab protocol. Weight-based (70 U/kg) intravenous heparin was given and activated clotting times of >250 seconds were maintained. Glycoprotein IIb/IIa inhibitor infusion and intravascular ultrasound were used at operator discretion. Ballooning and coronary stenting were performed in target lesions only after atherectomy was utilized (Figure 1).  We did not routinely place temporary pacemakers in any of the patients prior to OAS use. After the procedure, a TR Band (Terumo Corporation) was placed at the access site using patent hemostasis technique for four hours. Each patient was discharged home the following day and underwent 7-day and 30-day follow-up exams. Doppler ultrasound was performed in all patients to assess radial artery patency at 30 days. Finally, all patients received dual-antiplatelet therapy after the procedure. 

Results

Baseline patient and procedural characteristics are shown in Tables 1 and 2. The OAS was used in 27 patients with left anterior descending (LAD) lesions, with successful subsequent stent placement in 25 lesions. The remaining 2 patients received atherectomy followed by balloon dilatation only. The OAS was used in left main lesions in 3 patients. One of the lesions involved a diseased segment extending into the proximal portion of the LAD, while another lesion extended into the left circumflex (LCX). There were 7 right coronary artery (RCA) lesions and 13 LCX lesions. In all, 46 out of 50 patients received stents in the target lesion after orbital atherectomy. There was only 1 bifurcation lesion treated and none of the vessels had extreme tortuosity. There were 3 ostial lesions treated as well (LAD, diagonal, left main). There were no incidences of coronary perforation or hemodynamic compromise during the procedure. There was no need for the insertion of temporary pacemaker in any of the patients during or after any of the procedures. Average contrast volume used was 133.5 mL and average fluoroscopy time was 17.5 minutes. At the predetermined follow-up exams, no major adverse cardiovascular event (MACE), including cardiac death, myocardial infarction, and need for target-vessel revascularization, was observed. Cardiac markers were not checked routinely post PCI, as this is not standard practice at our institution. Clinical signs and symptoms were used to determine potential post-PCI events. There were no access-site complications noted immediately periprocedure and none of the patients required blood transfusions. Given the use of transradial access, the time to ambulation for all patients was almost immediately post procedure. Finally, the radial artery occlusion rate was found to be 6% at 30-day follow-up.

Discussion

Heavily calcified lesions have reduced elasticity with balloon expansion and increase the rate of perforations and dissections, which has therefore led to the development of plaque modification techniques prior to PCI.⁹ Rotational atherectomy (RA) has conventionally been used to increase vessel diameter prior to balloon angioplasty and stent placement. The mechanism of action involves the use of a rotating diamond-coated burr within the vessel that decreases calcium burden prior to further intervention.¹⁰ A study by Brogan et al demonstrated significant beneficial effects of calcium plaque reduction with RA, including a decrease in vessel stretch as well as less elastic recoil contributing to increased procedural success.¹¹ Furthermore, Moussa et al demonstrated a success rate of 93% in 75 consecutive patients with heavily calcified lesions treated with rotablation prior to coronary stenting.⁴ Some studies have shown that RA was involved in up to 10% of PCIs, but more recent analyses reveal that RA use has fallen to only 3%-5% in select high-volume centers.^12,13 The decrease in the use of RA may be due to the large size of the equipment, steep learning curve, and a lack of familiarity with RA in new operators.

The OAS is an alternative to traditional RA and was approved by the United States Food and Drug Administration in October 2013. The advantages of this device compared with RA include: (1) its ease of use; (2) smaller equipment size; (3) the ability to ablate forward and backward, minimizing burr entrapment rates; (4) no need for a foot pedal; (5) improved guidewire; and (6) only one choice of burr size that is capable of  increasing luminal diameter at higher speeds.

The ORBIT I trial was the first study to evaluate the efficacy of this novel atherectomy device. In this non-randomized prospective study, 50 patients underwent OAS atherectomy and PCI with a success rate of 94% and a cumulative MACE rate of 6% at 30 days and 8% at 6 months.¹⁴ In this trial, the use of OAS was not associated with slow-flow or distal embolization in any of the PCIs performed. This may be due to the OAS’s mechanism of action, which appears to create smaller particulates (2 µm) that may be captured by the reticuloendothelial system. Next, ORBIT II (the Pivotal Trial to Evaluate the Safety and Efficacy of the Orbital Atherectomy System in Treating De Novo, Severely Calcified Coronary Lesions) was a prospective, non-randomized multicenter study that further demonstrated both the safety and efficacy of this device in 440 patients. Freedom from MACE within 30 days post procedure was 89.6%, with a combined procedural success and freedom from MACE rate of 88.9%.⁹ In both of these major trials, the femoral approach was primarily used and therefore they did not evaluate the use of OAS exclusively via transradial access.   

In the present case series, every patient with a severely calcified lesion underwent successful atherectomy and PCI transradially, without converting to the femoral approach. More importantly, there were no adverse events periprocedurally or at follow-up. Temporary pacemakers were not required in any patients. Slow advancement of the burr, continuous flushing, and a coughing reflex alone were able to counteract any bradycardic events. This may reflect that the OAS may have less profound hemodynamic effects than other atherectomy devices.    . 

With transradial interventions rapidly gaining popularity and operators now treating more complex lesions, it is important to investigate any new devices or methods that may increase procedural success rates. The authors believe that the OAS can be safe and effective in treating calcified coronary lesions via transradial approach. However, the current study has important limitations, including its small size and observational design, which restrict any conclusions until a larger, multicenter, randomized controlled trial can be performed. Nonetheless, we believe that the use of OAS is feasible and the current study should spur other studies directly comparing treatments for calcified coronary lesions, especially using the transradial approach.

Conclusion

The OAS may be a safe and feasible option to assist in the treatment of severely calcified coronary lesions via transradial approach. Further randomized controlled trials are necessary to evaluate the safety and efficacy of this device. 

References

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From the ¹Mount Sinai Beth Israel New York, New York; ²Brown University Providence, Rhode Island; ³Brody School of Medicine at East Carolina Heart Institute, Greenville, North Carolina; and ⁴Apex Heart Institute, Gujarat, India.

Disclosure: The author has completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. The author reports no conflicts of interest regarding the content herein.

Manuscript submitted January 5, 2015, provisional acceptance given March 6, 2015, final version accepted April 6, 2015.

Address for correspondence: Tak W. Kwan, MD, Senior Associate Director of Cardiac Catheterization Laboratory and Interventional Cardiology, Mount Sinai Beth Israel, 139 Centre St, Rm 307, New York, NY 10013. Email: Kwancardio@aol.com