Orbital Atherectomy Via Transradial Access: A Multicenter Propensity-Matched Analysis

Abstract: Aims. The main objective of this study was to assess the safety and feasibility of orbital atherectomy (OA) with transradial access compared with more traditional femoral access. Methods. This multicenter, observational study included five tertiary-care centers. Out of the 39,870 who underwent percutaneous coronary intervention between January 2011 and January 2017, a total of 433 patients treated with coronary OA were identified and divided in two groups based on arterial access site. The co-primary outcomes of this study were major bleeding, associated blood transfusion, and safety outcomes. A propensity score was generated to match for baseline characteristics to avoid potential selection bias. Results. Transradial access was associated with significantly reduced major bleeding and blood transfusion in both the unadjusted model (0.6% vs 4.4% [P=.02] and 0.6% vs 4.8% [P=.02], respectively) and the propensity-score matched model (0.8% vs 6.5% [P=.045 for both]). There were no differences in safety outcomes, contrast use, fluoroscopy time, or any other secondary outcomes. Conclusions. In this real-world, multicenter, observational study, OA via transradial access was both safe and feasible. Furthermore, transradial access was associated with reduced bleeding complications and associated blood transfusion when compared with femoral access.

J INVASIVE CARDIOL 2019 July 15 (Epub Ahead of Print).

Key words: calcified coronary artery, orbital atherectomy, transfemoral, transradial access

Coronary artery calcification (CAC) presents numerous challenges to successful percutaneous coronary intervention (PCI).¹ Calcified coronary lesions are associated with difficulty to deliver a stent, stent under-expansion, and increased procedural and long-term adverse events.^2-5 Various devices, including rotational atherectomy, orbital atherectomy (OA), and laser atherectomy, have been utilized to mitigate this challenge. Historically, rotational atherectomy has been the most frequently utilized atherectomy device for treating de novo CAC. OA is a newer, adjunctive technique that can be used for lesion preparation mainly for severely calcified coronary lesions to facilitate stent implantation.⁶ The Diamondback 360° OA System (Cardiovascular Systems, Inc) can be used with a 6 Fr catheter system, allowing procedural access via the transradial approach in addition to the traditional transfemoral approach. Revascularization via transradial access has been increasing recently because of its safety profile.⁷ A recent meta-analysis of randomized controlled trials demonstrated that transradial access reduced mortality and increased safety, with reductions in major bleeding and vascular complications across the entire spectrum of patients with coronary artery disease (CAD).⁸ Additionally, a recent study demonstrated significant reduction in bleeding and access-site complications when using rotational atherectomy via transradial access.⁹ However, to date, no study has been published comparing outcomes assessing transradial versus femoral access when using OA.

We have previously reported the overall outcomes of atherectomy in a large, all-comer, multicenter study.¹⁰ The safety and feasibility of OA via transradial access has been suggested in a small (n = 50) single-center registry.¹¹ However, they did not compare transradial access directly with transfemoral access. This study included patients from COAP-PCI study cohorts.¹⁰ We sought to assess the in-hospital outcomes of patients treated with coronary OA prior to stent implantation in patients via transradial access.

Methods

Data source. This is a multicenter, retrospective analysis comparing outcomes in patients with CAC who were treated with OA via either transradial or transfemoral access. This study includes patients from five tertiary-care centers within a large health system based in New York. All data utilized in this study were collected using the National Cardiovascular Data Registry (NCDR) v4.4 form¹² and all definitions were utilized from the NCDR v4.4 Coder’s Dictionary.¹³ All study outcomes were adjudicated by the research team responsible for this project. This study was approved by the institutional review board. This database has been previously utilized and explained in detail in prior publications.^10,14

Study design and cohorts. This study database included patients treated between January 2011 and January 2017. The overall study cohort included 39,870 patients who underwent PCI during the study period. The initial case of OA, however, was identified in April 2013 following approval of OA for its commercial use in the United States. All patients who were treated with coronary OA as part of their PCI (n = 433) were included. Finally, we divided our patient population into two groups stratified by arterial access site (161 patients had transradial access and 272 patients had femoral access) (Figure 1). The decision for use of OA and access-site selection was at the operator’s discretion.

Endpoint and definitions. The primary endpoint of this study was major bleeding and associated blood transfusions. Co-primary outcomes included safety endpoints, such as significant dissection, perforation, cardiac tamponade, and major vascular complications. The secondary endpoints consisted of in-hospital mortality, myocardial infarction following PCI, stroke, new postprocedural cardiogenic shock, development of heart failure following PCI, new requirement for dialysis, procedure fluoroscopy time, contrast volume, and length of hospital stay. Cardiac enzymes were checked at the physician’s discretion. Endpoint definitions were based on the NCDR v4.4 Coder’s Data Dictionary as follows: (1) myocardial infarction: creatinine kinase or MB fraction >3x the upper limit of normal, or the development of a new pathological Q-wave on electrocardiography; and (2) major bleeding within 72 hours: hemoglobin drops of ≥3g/dL, blood transfusion, or blood loss requiring a procedural intervention to stop the bleeding.¹³

Device description. OA was approved for use in coronary arteries in the United States in 2013. OA employs an eccentrically mounted, diamond-coated burr that utilizes centrifugal force to orbit at either 80,000 or 120,000 rpm. The standard coronary crown size is 1.25 mm. OA exerts a differential ablative effect on hard and soft surfaces, producing particles <2 µm in size. The unique mechanism of OA allows for bidirectional ablation with continuous flow of blood during atherectomy. Continuous blood flow during ablation with OA may be associated with decreased thermal injury during the procedure, and decreased periprocedural complications.

Statistical analysis. All statistical analyses were performed using SAS 9.4 (SAS Institute). Continuous variables were analyzed using t-test and categorical variables were analyzed using Chi-square test or Fischer’s Exact test, as required. Continuous data were represented as mean ± standard deviation and categorical data were represented as frequency and percentage. Statistical significance was considered a P-value ≤.05.

A propensity-score match was generated to compare for outcomes with transradial versus femoral access. This study utilized a propensity-score matched model, as few differences in baseline characteristics were observed. Some differences, including (but not limited to) unavailability of femoral access due to tortuosity, infection, patient preference, or operator’s preference, were not accounted for in the model. A multilevel, hierarchical, logistic regression model was generated to calculate probability score considering femoral access as a control. In this model, the following variables were included: age; sex; race; body mass index; comorbidities; cardiogenic shock; presentation on admission; treated lesion site and characteristics; ejection fraction prior to PCI; and use of various mechanical circulatory devices. No patient with cardiac arrest on admission was identified in this study. Next, we matched both groups using a one-to-one scheme without replacement, using the nearest-matching neighbor method. This method also included caliper width of 0.1 for excellent match. This study excluded those patients who did not match. Categorical outcomes were compared with McNemar’s test and length of stay was compared using paired t-test. Finally, absolute standardized differences (ASDs) were calculated for all variables before and after the match. Post-match ASDs were <10% for all the variables observed, which is considered an excellent match.¹⁵

Results

A total of 433 patients were identified for this study. Overall use of OA increased from 2013 (n = 45) to 2016 (n = 159) (P_trend <.001). Overall characteristics for patients with OA have been summarized in a prior publication.¹⁰ Differences in demographics and baseline characteristics between transradial and transfemoral access cohorts are summarized in Table 1. The mean age of all patients included in this study was 71 years. Patients in the transradial group had a higher body mass index compared with patients in the transfemoral group (29.1 kg/m² vs 27.9 kg/m², respectively; P=.03). No differences between variables existed except for diabetes mellitus, which was higher in the transradial group (60.3% vs 46.7% in the femoral access group; P<.01). More patients presented with acute coronary syndrome in the transfemoral group (38.2% vs 30.4% in the transradial group; P=.03). The prevalence of the following variables was highest in both groups: hypertension (95.1%), dyslipidemia (92.4%), diabetes mellitus (51.7%), prior PCI (44.8%), and prior myocardial infarction (34.9%).

The right coronary artery was the most commonly treated vessel (77.1%) using OA in this study. Overall, 16% of lesions involved bifurcation lesions, with a greater prevalence of bifurcation lesions in the transfemoral group (18.7% vs 11.0% in the transradial group; P=.04). Left main and left anterior descending coronary artery lesions were treated more often using transradial artery access in this study. Mean ejection fraction for the overall population was 51.6%, without any difference between the two groups. Mechanical circulatory devices were utilized more frequently in the transfemoral group (8.1% vs 3.1% in the transradial group; P=.03) (Table 2).

Primary and secondary outcomes were compared before and after performing propensity-score matched analysis. (Figure 2 and Supplemental Table S1). Demographics and baseline characteristics post match are presented in Supplemental Table S1. The major bleeding within 72 hours (0.6% in the transradial group vs 4.4% in the transfemoral group; P=.02) and blood transfusion (0.6% in the transradial group vs 4.8% in the transfemoral group; P=.02) was noted to be significantly lower in patients with transradial artery access. This difference remained significant even after comparing major bleeding and blood transfusion in propensity-score matched patients (0.8% in the transradial group vs 6.5% in the transfemoral group; P=.045 for both). No difference in the use of fluoroscopy time or contrast volume was observed. Additionally, no differences in myocardial infarction, cardiogenic shock, heart failure, or length of stay were observed between two groups. No in-hospital mortality occurred in either group (Table 3 and Supplemental Table S2).

Discussion

This study reports procedural and in-hospital outcomes in patients treated with OA stratified by transradial versus transfemoral artery access. The major findings of this study are as follows: (1) OA via the transradial approach is both safe and feasible; (2) transradial access was associated with significantly less postprocedure bleeding and need for blood transfusion; and (3) there were no significant differences in contrast use, fluoroscopy time, or length of stay based on access site used. To our knowledge, this is the first study comparing in-hospital outcomes for transradial versus transfemoral access for patients treated with OA prior to PCI.

This study demonstrated lower rates of bleeding and associated blood transfusion with transradial access without any difference in in-hospital mortality between transradial and transfemoral access groups. This is increasingly important, as the proportion of transradial access for PCI continues to rise worldwide.⁷ Additionally, bleeding complications¹⁶ and blood transfusions¹⁷ were strongly associated with increased periprocedural mortality. Furthermore, bleeding was associated with higher risk for ischemic events.¹⁸ Taken together, transradial access may have cost benefits that help offset any added procedural costs from adjunctive atherectomy.¹⁹ As OA can be used with a 6 Fr catheter system, access-site selection does not preclude its use. It is unknown if differences in long-term outcomes, including target-vessel revascularization and mortality, differ by access-site selection in patients treated with atherectomy. However, a similar 30-day safety profile with transradial access was demonstrated for rotational atherectomy.⁹ Finally, access-site associated bleedings were not associated with increased mortality, myocardial infarction, thrombosis, or stroke in a previous study.²⁰

OA using transradial access may involve a small learning curve as compared with traditional PCI; however, it is both safe and feasible with experienced operators, and it is increasingly being utilized in complex lesions with CAC.²¹ A recently published consensus statement demonstrated that smaller burr size is generally required for modification using rotational atherectomy with transradial access.²¹ As all coronary OA utilizes a 1.25 mm burr, OA can be performed with a 6 Fr guiding catheter, permitting transradial access regardless of vessel size treated.²¹ There was no difference between groups in the rate of procedural complications, including dissection, perforation, or tamponade, and these were unlikely to have impacted bleeding outcomes. As such, it is unclear whether the difference in bleeding detected between groups was independent from any effect of OA. Finally, no difference in vascular complications was appreciated in this study. Further studies are needed to identify the cause of reduced bleeding in patients treated with OA via the transradial approach.

This was not a randomized clinical trial, and consequently we cannot determine causation with access-site selection in patients undergoing atherectomy. Future randomized controlled trials should evaluate whether such a causal relationship exists. This study demonstrates an important association between major bleeding and access site when using OA. Ferrante et al demonstrated that benefits with transradial approach over femoral approach applied to all patient subgroups, which indicates consistent benefits with this approach in any complex CAC lesion.⁸ It is important to note that successful revascularization via transradial access is associated with greater operator experience.²² This study took place at institutions where a specific emphasis existed on training development programs to increase the use of transradial access for complex PCI, including with use of atherectomy. Nonetheless, patients treated with OA represent a complex patient cohort and this study demonstrates the safety of transradial access as a default approach when using OA to improve clinical outcomes and minimize complications. The ongoing, pivotal ECLIPSE trial (NCT03108456) is evaluating treatment strategies for severely calcified coronary arteries with a comparison between OA and conventional angioplasty techniques. Insight from this multicenter trial, which has an expected enrollment of 2000 patients, will provide additional data on the optimal management strategies for these patients.

Study limitations. Our study has a number of important limitations. First, specific OA procedural data, such as speed settings and number of passes, were not tracked. Additionally, this study did not collect arterial sheath size and guiding catheter size, which is typically smaller with transradial access. Transradial access is also a safe and effective method when using a sheathless approach.²³ Second, a core laboratory was not used in this study. As a result, the diagnosis of severe CAC and the decision to use OA was at the operator’s discretion, as is typical in a real-world setting. Third, follow-up data beyond index hospitalization were not available for this study. Fourth, as this was not a randomized study, inherent differences in patient risk may not have been accounted for in the propensity-matched model. Additionally, operator preference and technique may have influenced the decision for access site, and as such may have influenced outcomes. Finally, patient medication history was not available for analysis, and it is unknown whether differences between pharmacotherapy between groups may have accounted for differences in bleeding events.

Conclusion

In this all-comer, multicenter, observational study, OA via transradial access was both safe and feasible. Furthermore, transradial access was associated with reduced bleeding complications when compared with patients treated with femoral access.

References

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From the ¹Department of Cardiology, North Shore University Hospital, Manhasset, New York; ²Department of Internal Medicine, University of Nevada Reno School of Medicine, Reno, Nevada; and the ³Department of Cardiology, MedStar Washington Hospital Center, Washington, D.C.

Disclosure: The authors have completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. The authors report no conflicts of interest regarding the content herein.

Manuscript submitted March 5, 2019 and accepted March 14, 2019.

Address for correspondence: Rajkumar Doshi, MD, MPH, Department of Internal Medicine, University of Nevada Reno School of Medicine, 1155 Mill St W1, Reno, NV 89502. Email: raj20490@gmail.com