Multicenter Registry of Real-World Patients With Severely Calcified Coronary Lesions Undergoing Orbital Atherectomy: 1-Year Outcomes

Abstract: Objectives. We report the 1-year outcomes of real-world patients with severely calcified coronary arteries who underwent orbital atherectomy. Background. Percutaneous coronary intervention of heavily calcified lesions is technically challenging and associated with worse clinical outcomes. Modification of severely calcified coronary lesions with orbital atherectomy facilitates stent delivery and expansion. Although we previously reported the safety of orbital atherectomy at 30 days in all comers with severely calcified coronary lesions, including patients who were excluded from the ORBIT II trial, longer-term follow-up is unknown. Methods. We retrospectively analyzed 458 all-comer patients who underwent orbital atherectomy followed by stenting from October 2013 to December 2015 at three centers. The primary endpoint was the 1-year major adverse cardiac and cerebrovascular event (MACCE) rate, defined as the composite of death, myocardial infarction, target-vessel revascularization, and stroke. Results. One-year data were available for 453/457 patients (98.9%). At 1-year follow-up, the MACCE rate was 12.6%, death rate was 4.0%, myocardial infarction rate was 1.8%, target-vessel revascularization rate was 7.5%, stroke rate was 1.3%, and stent thrombosis rate was 1.3%. Conclusion. Orbital atherectomy is a valuable option for the treatment of severely calcified coronary arteries, including patients with very complex coronary anatomy and severe underlying comorbid conditions. Orbital atherectomy provided acceptable outcomes at 1 year and compared favorably to historical controls. A randomized trial with longer follow-up is needed to determine the optimal treatment strategy for patients with severely calcified coronary lesions. 

J INVASIVE CARDIOL 2018;30(4):121-124.

Key words: orbital atherectomy, lesion calcification

The presence of heavily calcified lesions increases the complexity of percutaneous coronary intervention (PCI), as it may prevent stent delivery.¹ It can also impede full expansion, increasing the risk of stent restenosis and thrombosis. Attempts to dilate a calcified lesion that is resistant to high-pressure balloon inflations can lead to angiographic complications, including coronary perforation and dissection. Furthermore, PCI of severely calcified lesions is associated with worse clinical outcomes, including death, myocardial infarction, repeat revascularization, and stent thrombosis.² 

The 2011 American College of Cardiology/American Heart Association PCI guidelines state that rotational atherectomy is recommended for fibrotic or heavily calcified lesions that might not be crossed by a balloon catheter or adequately dilated before stent implantation (class 2a, level of evidence C).³ However, there are currently no recommendations for orbital atherectomy, which also modifies calcified plaque, facilitating stent delivery and expansion. The ORBIT (Evaluate the Safety and Efficacy of OAS in Treating Severely Calcified Coronary Lesions) II trial, which was a single-arm, prospective, multicenter study of 443 patients who underwent orbital atherectomy for severely calcified lesions, reported low angiographic and ischemic complication rates at 1 year.^4,5 However, patients with recent myocardial infarction, severe left ventricular systolic function (ejection fraction ≤25%), long diffuse lesions (>40 mm), or unprotected left main disease were excluded. We previously reported the 30-day outcomes of all comers with severely calcified lesions who underwent orbital atherectomy followed by stenting.⁶ We report the 1-year outcomes from this real-world, multicenter registry of patients who underwent orbital atherectomy. 

Methods

Study population. This is a retrospective study of 458 patients who underwent orbital atherectomy for severely calcified coronary lesions between October 2013 to December 2015 at three centers (UCLA Medical Center, Los Angeles, California; St. Francis Hospital, Roslyn, New York; and Northwell Health, Manhasset, New York). Severely calcified coronary lesions were defined by the fluoroscopic presence of radiopacities involving the vessel wall.  The institutional review board at each site approved the review of the data. 

Device description, procedure, and medical treatment. The description of the device, procedure, and medical treatment was previously published.⁶ The Diamondback 360° coronary orbital atherectomy system (Cardiovascular Systems, Inc. [CSI]) is advanced over a 0.014˝ ViperWire guidewire (CSI) as the ViperSlide lubricant (CSI) decreases the friction during ablation. The diamond-coated crown is 30 microns in diameter and eccentrically mounted, and laterally expands due to centrifugal force while rotating on the ViperWire.  

After low-speed atherectomy (80,000 rpm), high-speed atherectomy (120,000 rpm) was performed at the operator’s discretion if the reference vessel diameter was ≥3.0 mm. The typical duration of each pass was limited to 20 seconds. The choices of stent type (drug-eluting or bare-metal), antithrombotic therapy (heparin or bivalirudin), and the use of hemodynamic support device, intravascular imaging (intravascular ultrasound or optical coherence tomography), and transvenous pacemaker were left to the operator’s discretion. Patients were treated with aspirin and a P2Y12 inhibitor for a minimum of 1 month after bare-metal stent implantation and 12 months after drug-eluting stent implantation. 

Study endpoints and clinical follow-up. The primary endpoint was 1-year rate of major adverse cardiac and cerebrovascular event (MACCE), defined as the composite of death, myocardial infarction, target-vessel revascularization, and stroke. Myocardial infarction was defined as recurrent symptoms with new ST-segment elevation or re-elevation of cardiac markers >2x upper limit of normal. Target-vessel revascularization was defined as a repeat revascularization of the target lesion because of restenosis within the stent or in the 5 mm distal or proximal segments. The Academic Research Consortium definition of stent thrombosis was used.⁷ Patient demographics, angiographic and procedural characteristics, and clinical data were collected from medical records and entered into a dedicated PCI database.  

Statistical analysis. Continuous variables are presented as mean ± standard deviation. Categorical variables are presented as frequencies and percentages. Statistical analyses were performed using SAS version 9.1 (SAS Institute). 

Results

The orbital atherectomy device could not traverse the severely calcified lesion in 2 patients. The device was removed in another patient when ST-elevation developed on the electrocardiogram upon engaging the lesion. One-year data were available in 453 patients (98.9%). The prevalence of diabetes mellitus was high (42.1%), and 11.1% presented with non-ST elevation myocardial infarction (Table 1).

Stents were successfully implanted in 99.1%, and drug-eluting stents were used in the vast majority of cases (92.1%) (Table 2). Angiographic complications were low; perforation occurred in 0.7%, dissection occurred in 0.9%, and no-reflow occurred in 0.7% (Table 3). 

The primary endpoint of MACCE at 1 year occurred in 12.6% (Table 4). At 1 year, the mortality rate was 4%, myocardial infarction rate was 1.8%, target-vessel revascularization rate was 7.5%, and stroke rate was 1.3%. The stent thrombosis rate at 1 year was 1.3%. 

Discussion

The principal finding of this study was that orbital atherectomy provided favorable results that were observed at 30 days and extended up to 1 year in patients with heavily calcified coronary lesions. 

Severely calcified coronary arteries may decrease the procedural success of PCI due to the inability to deliver a balloon or stent to the lesion. Furthermore, these lesions are difficult to predilate, and it is challenging to obtain optimal stent expansion. Coronary atherectomy effectively prepares the calcified lesion to improve the procedural success. In the ROTAXUS (Rotational Atherectomy Prior to Taxus Stent Treatment for Complex Native Coronary Artery Disease) trial, rotational atherectomy improved the overall success rate compared with standard therapy (92.5% vs 83.3%; P=.03) and decreased the rate of stent loss (0.0% vs 2.5%).⁸ No patients experienced stent loss, and successful stent delivery with orbital atherectomy in our real-world registry was 99.1%.⁶

This multicenter registry included patients who are encountered in real-world practice but would have been excluded from the ORBIT II trial. Patients with myocardial infarction, cardiac arrest, cardiogenic shock, and unprotected left main disease, as well as those who were on hemodynamic support devices, intubated, and had very high mortality risk and thus were turned down for surgical revascularization, were included in this study. Despite successful PCI with excellent angiographic results, patients died from non-procedure related causes given their severe underlying comorbidities at the time of orbital atherectomy, including multiorgan failure and shock on vasopressors. 

Our results compared favorably with historical controls. The 1-year all-cause mortality rate in our analysis was 4%, compared with 3.0% cardiac death in the ORBIT II trial.⁵ In the ROTAXUS trial, the 9-month mortality rates were 5.0% in patients who underwent paclitaxel-eluting stent implantation with rotational atherectomy and 5.8% in patients who underwent paclitaxel-eluting stent implantation without rotational atherectomy.⁸ The 1-year rate of target-vessel revascularization was 7.5% in our real-world registry, compared with 5.9% in the ORBIT II trial.⁵ In the ROTAXUS trial, the 9-month target-vessel revascularization rate in the patients who underwent PCI with paclitaxel-eluting stenting with no rotational atherectomy was 18.3% in the paclitaxel-eluting stent group.⁸ A possible explanation for the higher rates of target-vessel revascularization in patients who did not undergo atherectomy may be due to suboptimal stent expansion and damage of the polymer during stent delivery by the calcified plaque.⁹ Stent thrombosis at 1 year was also low in our study (1.3%), suggesting that orbital atherectomy provided adequate lesion preparation, which facilitated optimal stent expansion. 

Orbital atherectomy has several theoretical advantages compared with rotational atherectomy. One advantage is the shorter fluoroscopy time with orbital atherectomy due to differences in time and operations.¹⁰ In a severely stenotic calcified lesion in a large-diameter vessel (≥3.5 mm), rotational atherectomy may require initial ablation with a 1.25 mm burr, followed by removal, detachment, attachment of a large burr (≥1.75 mm), and reinsertion. The added time of using two different burrs may not be well tolerated in patients who develop ischemia or are hemodynamically unstable. In contrast, initial orbital atherectomy with a 1.25 mm crown at low speed can then be easily escalated to high-speed atherectomy, achieving sufficient plaque modification without the need to remove the device. Another advantage is that the set-up is easier and faster, as orbital atherectomy is a self-contained system, obviating the need for a nitrogen tank, pedal, and a console that requires adjustment to attain the desired speed. The ViperWire is more practical and can be used to advance balloons and stents to complete the PCI compared with the RotaWire, which is 0.009˝ in diameter and lacks the support.

Study limitations. This was a non-randomized, retrospective study that did not have a comparison group. Because routine coronary angiography was not performed at 1 year, the rate of in-stent restenosis is unknown. A core laboratory did not assess the coronary angiograms or perform quantitative coronary analysis. A clinical events committee did not adjudicate clinical events. The three clinical sites are high-volume centers for orbital atherectomy with experienced operators. Therefore, it is uncertain whether these findings can be generalized to all patients.  

Conclusion

Orbital atherectomy is a safe treatment option and provides acceptable intermediate outcomes in patients with high-risk lesions. The target-vessel revascularization rate at 1 year was reassuring despite the long, diffuse, complex nature of many of these lesions. A randomized trial with longer-term follow-up comparing different treatment, percutaneous, and surgical strategies is needed to determine the optimal treatment for heavily calcified coronary artery lesions. 

References

1.    Lee MS, Shah N. The impact and pathophysiologic consequences of coronary artery calcium deposition in percutaneous coronary interventions. J Invasive Cardiol. 2016;28:160-167. 

2.    Lee MS, Yang T, Lasala J, Cox D. Impact of coronary artery calcification in percutaneous coronary intervention with paclitaxel-eluting stents: two-year clinical outcomes of paclitaxel-eluting stents in patients from the ARRIVE program. Catheter Cardiovasc Interv. 2016;88:891-897. 

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4.    Chambers JW, Feldman RL, Himmelstein SI, et al. Pivotal trial to evaluate the safety and efficacy of the orbital atherectomy system in treating de novo, severely calcified coronary lesions (ORBIT II). JACC Cardiovasc Interv. 2014;7:510-518.

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6.    Lee MS, Shlofmitz E, Kaplan B, et al. Real-world multicenter registry of patients with severe coronary artery calcification undergoing orbital atherectomy. J Interv Cardiol. 2016;29:357-362.  

7.    Cutlip DE, Windecker S, Mehran R, et al; Academic Research Consortium. Clinical end points in coronary stent trials: a case for standardized definitions. Circulation. 2007;115:2344-2351.

8.    Abdel-Wahab M, Richardt G, Joachim Buttner H, et al. High-speed rotational atherectomy before paclitaxel-eluting stent implantation in complex calcified coronary lesions: the randomized ROTAXUS (Rotational Atherectomy Prior to Taxus Stent Treatment for Complex Native Coronary Artery Disease) trial. JACC Cardiovasc Interv. 2013;6:10-19.

9.    Kuriyama N, Kobayashi Y, Yamaguchi M, Shibata Y. Usefulness of rotational atherectomy in preventing polymer damage of everolimus eluting stent in calcified coronary artery. JACC Cardiovasc Interv. 2011;4:588-589.

10.    Sareen N, Baber U, Aquino M, et al. Mid-term outcomes of consecutive 998 cases of coronary atherectomy in contemporary clinical practice. J Interv Cardiol. 2017;30:331-337.

From the ¹Division of Interventional Cardiology, UCLA Medical Center, Los Angeles, California; ²Division of Interventional Cardiology, Columbia University Medical Center, New York, New York; and ³Division of Cardiology, St. Francis Hospital, Roslyn, New York. 

Disclosure: The authors have completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. Drs Lee, E. Shlofmitz, and R. Shlofmitz

report honoraria from Cardiovascular Systems, Inc. Mr Goldberg reports no conflicts of interest regarding the content herein.

Manuscript submitted September 26, 2017, provisional acceptance given October 9, 2017, final version accepted October 13, 2017.

Address for correspondence: Dr Michael S. Lee, 100 Medical Plaza, Suite 630, Los Angeles, CA 90095. Email: mslee@mednet.ucla.edu