Clinical Outcomes of Atherectomy Prior to Percutaneous Coronary Intervention: A Comparative Assessment of Atherectomy in Patients With Obesity (COAP-PCI Subanalysis)

Abstract: Objectives. The aim of this study was to investigate the safety and efficacy of atherectomy devices in obese patients with coronary artery calcification (CAC). Background. Atherectomy is an important tool for lesion preparation in patients with CAC undergoing percutaneous coronary intervention (PCI). There have been no studies that compared the outcomes of orbital atherectomy (OA) and rotational atherectomy (RA) in obese patients. Methods. A total of 35,590 patients from five tertiary-care hospitals who underwent PCI between January 2011 to April 2016 were identified. All adult patients with body mass index ≥30 kg/m² who had OA or RA prior to PCI were included in this analysis. A total of 91 patients were included in the OA arm and 131 patients in the RA arm prior to the matching. To remove potential selection bias, a propensity-score matched analysis was performed, and 69 patients were included in each group. Results. The primary endpoint, composite of safety outcomes, did not occur in any patient of either group. The secondary endpoints – death on discharge (0.0% vs 1.5%; P=.48) and myocardial infarction (2.9% vs 6.4%; P=.42) – were similar between groups, as were individual outcomes including cardiogenic shock, bleeding complications, and congestive heart failure. Stroke, vascular complications, and the requirement for dialysis initiation did not occur in any of the patients. Conclusion. In this study assessing atherectomy in obese patients, OA and RA demonstrated comparable outcomes with complication rates within an acceptable range. It demonstrates that OA and RA can be safely performed in this high-risk patient subset with CAC. 

J INVASIVE CARDIOL 2018;30(12):465-470. Epub 2018 October 15.​

Key words: coronary artery calcification, obesity, orbital atherectomy, rotational atherectomy, percutaneous coronary intervention

Calcified coronary lesions are frequently encountered in clinical practice, with an increasing prevalence. Although reported in 38% of all lesions by angiography, coronary artery calcification (CAC) can be identified in 74% of cases when intravascular ultrasound (IVUS) evaluation is performed.¹ CAC complicates percutaneous coronary intervention (PCI) and increases the risk of periprocedural adverse events and need for revascularization.^2,3 There is a strong association with CAC and stent under-expansion,³ which is a key independent predictor for failure of stents due to restenosis.⁴ Consequently, lesion preparation is a key component to optimize outcomes from PCI and is often accomplished with atherectomy. The incidence of obesity has been increasing and now affects more than one-third of adults in the United States.⁵ Obesity is a known independent risk factor for cardiovascular disease.⁶ Data on the effects of obesity on procedural outcomes of PCI have been conflicting. There have been no known reports of the impact of obesity on patients undergoing atherectomy as part of coronary revascularization. 

We previously presented the outcomes of patients undergoing rotational atherectomy (RA; Boston Scientific) or orbital atherectomy (OA; Cardiovascular Systems, Inc.) in the all-comers COAP-PCI (Clinical Outcomes of Atherectomy Prior to Percutaneous Coronary Intervention) study.⁷ This study slightly favored OA over RA in terms of in-hospital mortality and myocardial infarction (MI). Here, we sought to evaluate the outcomes of atherectomy in obese patients, comparing those treated with OA and RA.

Methods

Study design. This retrospective, observational analysis included 222 consecutively treated patients who underwent either RA or OA between January, 2011 and April, 2016 at five different tertiary-care hospitals that were part of a large health-care system (Figure 1). All outcomes were adjudicated by the research team responsible for this project. This study was approved by the institutional review board. 

Patient selection criteria. All patients >18 years old who underwent PCI with either OA or RA were included. Patients with a body mass index (BMI) <30 kg/m² were excluded. BMI data were derived using height and weight on admission. Patients with laser atherectomy or directional atherectomy were excluded from this study. All demographics, baseline characteristics, procedural characteristics, and in-hospital outcome data were collected.

Definitions. The National Cardiovascular Data Registry (NCDR)version 4.4 was used to collect data for all variables included in our study; the information was compiled in a dedicated database.⁸ For patients on dialysis on admission, both hemodialysis and peritoneal dialysis were included. Current smokers were defined as all patients smoking currently as well as those who smoked within the prior year. Cerebrovascular disease was defined as hemorrhagic and ischemic stroke, including the history of transient ischemic attacks. Chronic lung disease was defined as patients with moderate to severe chronic obstructive pulmonary disease and/or patients on home oxygen. Other mechanical circulatory support (MCS) use included Impella 2.5, Impella CP, and Impella 5.0 (Abiomed, Inc). 

Study endpoints. The primary endpoint was the composite of procedural complications including significant dissection, perforation, or cardiac tamponade. Secondary endpoints included in-hospital mortality, MI, cardiogenic shock, congestive heart failure, stroke, new requirement for dialysis, vascular complication, blood transfusion, bleeding within 72 hours, and length of stay. Procedural outcomes including fluoroscopy time and contrast volume were evaluated. MI was defined as cardiac enzymes 10x the upper limit of normal or the development of new pathological Q-waves on electrocardiogram.⁹Major bleeding events were defined as a hemoglobin drop of ≥3 g/dL, blood transfusion, or blood loss requiring a procedural intervention to stop the bleeding. Significant dissection was defined as grades C-F. New development of cardiogenic shock was defined as systolic blood pressure <90 mm Hg for >30 minutes or signs of end-organ failure. All definitions used were consistent with the NCDR version 4.4. 

Statistical analysis. Statistical analysis was performed using SAS 9.4 (SAS Institute, Inc). Differences between categorical variables were tested using the Chi-square test, and differences between continuous variables were tested using the Student’s t-test. Categorical data are presented as frequency (percentage). Continuous data are presented as mean ± standard deviation. A propensity-score matched model was generated to compare primary and secondary outcomes between admissions with OA and RA. First, a logistic regression model was performed on all baseline characteristics, including age, gender, comorbidities, procedural characteristics, and culprit lesion site to calculate the propensity score for each individual patient. All patients were then matched using a one-to-one scheme without replacement using the nearest number matching method. Absolute standardized difference below 10 was assured for all covariates after matching and is considered acceptable.¹⁰ Finally, we compared primary and secondary outcomes using McNemar’s test or paired t-test as appropriate. 

Results

A total of 222 patients with BMI ≥30 kg/m² were identified with either OA (41%) or RA (59%) used prior to PCI. Overall mean age was 68.8 years. Mean patient age was higher in the RA group vs the OA group (67.4 years vs 70.3 years, respectively; P=.04). BMI was comparable between the two groups (35.2 kg/m² in the RA group vs 34.5 kg/m² in the OA group; P=.32). More males (n = 147) were included in the study population compared to females (n = 75) (Table 1). White/Caucasian patients (n = 151) were predominant in our study group, followed by black/African-American patients (n = 34). No significant baseline comorbidity differences were noted between groups except for the rates of prior MI, prior PCI, and prior coronary artery bypass graft (CABG) surgery, which were higher with RA than with OA. Use of intraaortic balloon pump (4.1%) and other MCS (4.1%) was limited and equal in both the groups. Two-thirds of the patients had femoral arterial access. Unfractionated heparin was administered in 50% of the patients, with slightly higher utilization in the OA group (60.4% vs 44.3% in the RA group; P=.02). No difference existed in preprocedural ejection fraction (EF) or lesion length. Lesion diameter was slightly larger in the OA group (2.6 mm vs 2.4 mm in the RA group; P=.04). The most common culprit lesion for both groups was the right coronary artery, followed by the left anterior descending artery, left circumflex coronary artery, and left main artery (Table 2). On presentation, most patients presented with stable and unstable angina (Supplemental Table S1; supplemental information available at bottom of Results section).

After performing propensity-score matching, a total of 69 patients were included in each group (Supplemental Tables S2 and S3). No significant baseline differences remained after performing propensity-score matching (Figure 2). The primary endpoint did not occur in either group (Table 3). There was no difference in in-hospital mortality between the groups (odds ratio [OR], 1.02; (95% confidence interval [CI], 0.98-1.05). No difference was noted in any other secondary outcome, including MI (OR, 2.24; 95% CI, 0.39-12.7), cardiogenic shock (OR, 2.20; 95% CI, 0.19-24.9), congestive heart failure (OR, 1.02; 95% CI, 0.98-1.05), blood transfusion (OR, 2.24; 95% CI, 0.39-12.7), and bleeding within 72 hours (OR, 0.80; 95% CI, 0.17-3.73). No periprocedural stroke, requirement for new dialysis, or vascular complications occurred in either group. There was a trend toward shorter length of hospitalization stay in patients treated with OA (1.2 days vs 2.1 days in the RA group; P=.06). Thrombolysis in Myocardial Infarction (TIMI) flow grades at baseline and post intervention are depicted in Supplemental Figure S1. TIMI flow 3 was achieved at the end of the atherectomy procedure in all patients included in this study.

Supplemental Data

Discussion

This analysis highlights the differences in obese patients treated with OA or RA prior to PCI. Patients undergoing RA were older and had higher rates of prior MI, prior PCI, and prior CABG. However, this study represents a “real-world” scenario and did not exclude any treated patients. This study demonstrated that OA and RA are both safe and effective in treating high-risk patients with CAC. We did not observe any differences in primary or secondary outcomes after propensity-score matching for those patients treated with OA or RA. Finally, TIMI grade 3 was achieved in all patients.

Calcified coronary artery disease is associated with an independent and progressive increase in risk for all-cause mortality and cardiac events.^11,12 A “calcification paradox” has been reported, suggesting an inverse correlation between BMI and index lesion calcification.¹³ Nonetheless, patients with obesity and severely calcified lesions are often encountered in clinical practice. While there is conflicting literature on whether obesity is an independent risk factor for worse events during PCI, it appears there is a paradoxical reduction in events, although the degree of obesity impacts outcomes.^14-17 This may be influenced by intensive medication regimens prevalent in obese patients during study follow-up.¹⁸

Interest in atherectomy has grown in recent years with the increasing incidence and detection of CAC. RA was first introduced in 1988 by David Auth and utilizes differential cutting to achieve debulking.^19,20 OA is a newer modality approved in 2013 that uses differential ablation to change lesion compliance for lesion preparation.²¹ RA can reach speeds of 160,000 to 200,000 rpm, while OA can reach speeds of 80,000 to 120,000 rpm. Resulting debris using RA (5 µm) and OA (<2 µm) are very small. Although OA and RA are based on unique mechanisms with different clinical indications, there has been much attention to comparisons of the two modalities, with the publication of a number of recent observational comparative studies.^22-26 Furthermore, atherectomy can help achieve complete revascularization and optimize results.²⁷ Complete revascularization in a single setting can help achieve improved long-term outcomes in acute coronary syndrome patients without cardiogenic shock.^28,29

No major angiographic complications (dissection, perforation, tamponade) occurred in either cohort, suggesting that both OA and RA are safe during PCI in patients with obesity. Neither atherectomy device was associated with periprocedural risk of in-hospital MI, stroke, or death in patients with elevated BMI in our study. Our results suggest that both RA and OA can be safely performed in appropriate patients with obesity and heavily calcified coronary artery disease. Future studies must focus on long-term outcomes to assess optimal revascularization strategies in this complex patient population. 

Study limitations. The COAP registry is a retrospectively collected continuous patient database; however, it is non-randomized. Although propensity-score matching was performed, potential confounders such as selection bias can remain. Additionally, we lost 38% of the patients in the process of matching. These confounding factors cannot be matched and need to be studied in a prospective trial. Diagnosis of severe calcification, election for treatment with atherectomy, and the specific device used were at the discretion of the operator. The overall length of follow-up was short and limited to the hospital length of stay. Cardiac enzymes were checked at the operator’s discretion when clinically warranted; as a result, periprocedural MIs were likely to have been under-diagnosed, although our data likely represent a valid rate for clinically significant MI. Systematic under-reporting is inherent in a real-world retrospective analysis; however, equal ascertainment of outcomes occurred in both arms. Although historically most complications with atherectomy occurred during the index hospitalization, target-vessel revascularization could not be assessed because of the short follow-up. Additionally, OA was not performed from 2011-2013, and as a result, potential confounders unaccounted by propensity matching may remain, including variations in operator skill and experience that occurred during that period. The findings from this large comparison of OA and RA are associative due to the study design.

Conclusion

CAC increases the complexity of PCI. The impact of obesity on patients undergoing revascularization with atherectomy is unknown. This study demonstrated both OA and RA to be safe, and showed outcomes within an acceptable range in this complex obese patient population.

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From the Department of Cardiology, North Shore University Hospital, Northwell Health, Manhasset, New York. 

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 August 4, 2018, final version accepted August 19, 2018.

Address for correspondence: Perwaiz Meraj, MD, FACC, FSCAI, Associate Professor of Cardiology, Director of Fellowship Research, Department of Cardiology, Northwell Health, Zucker School of Medicine at Hofstra/Northwell, 300 Community Drive, Manhasset, NY 11030. Email: PMeraj@northwell.edu