Original Contribution

Orbital Atherectomy for Calcific Coronary Artery Disease in Patients With Severe Aortic Stenosis: A Safety and Feasibility Study

Ibrahim Kassas, MD;  Ahmed Nagy, MD;  Alvaro Alonso, MD;  Mohammed Waseem Akhter, MD;  Craig S. Smith, MD;  Mohamed Ahmed, MD;  Abdul Moiz Hafiz, MD;  Jennifer Walker, MD;  Nikolaos Kakouros, BSc, MBBS, MD(Res), PhD, FRCP

Ibrahim Kassas, MD;  Ahmed Nagy, MD;  Alvaro Alonso, MD;  Mohammed Waseem Akhter, MD;  Craig S. Smith, MD;  Mohamed Ahmed, MD;  Abdul Moiz Hafiz, MD;  Jennifer Walker, MD;  Nikolaos Kakouros, BSc, MBBS, MD(Res), PhD, FRCP

Abstract: Background. Percutaneous revascularization followed by transcatheter aortic valve replacement (TAVR) has been increasingly utilized as an alternative to surgery in patients with severe aortic stenosis (AS) and coronary artery disease (CAD). In many of these patients, the coronary arteries are severely calcified and may best be treated with atherectomy; however, atherectomy is not routinely performed in severe AS patients due to safety concerns. There is a paucity of data on the safety of orbital atherectomy (OA) in patients with severe AS and concurrent calcific CAD. Methods. We retrospectively analyzed the medical records of all patients with severe AS who underwent OA-facilitated percutaneous coronary intervention (PCI) at our center between September 1, 2015 and November 1, 2018. Results. Twenty-four patients (mean age, 82.5 ± 7.6 years) were identified. Mean aortic valve area was 0.68 ± 0.26 cm and mean aortic valve gradient was 43 ± 17.7 mm Hg. All PCIs were successful (mean diameter stenosis, 80.8 ± 11%; mean number of passes, 5.3 ± 3.3). Two patients had planned hemodynamic support, with left ventricular assist device and intra-aortic balloon pump; none of the patients required vasopressors during PCI. There was a slight reduction in heart rate during OA (71.6 bpm vs 63.3 bpm; P=.02), with no major procedure-related clinical events. Only 1 patient (4.2%) with pre-existing conduction system disease required transient pacing from his permanent pacemaker during OA. All procedures were completed successfully and there were no periprocedural deaths or clinical myocardial infarctions. Conclusion. OA-facilitated PCI can be safely performed in patients with severe AS and severely calcified CAD with low risk of complications. There was no significant change in blood pressure and heart rate during OA, with minimal need for temporary pacing.

J INVASIVE CARDIOL 2019;31(7):E205-E210.

Key words: aortic stenosis, orbital atherectomy, OA, PCI, TAVR


Non-rheumatic calcific aortic stenosis (AS) is the most common form of valvular heart disease in elderly patients. AS occurs frequently in conjunction with coronary artery disease (CAD).1,2 Historically, the standard of care for patients with calcific AS and CAD has been synchronous surgical aortic valve replacement (SAVR) and coronary artery bypass grafting (CABG).1 In recent years, however, transcatheter aortic valve replacement (TAVR) has proven to be a safe and reliable option for elderly patients with AS who are intermediate to high risk from SAVR.2-10 Approximately one-third of these patients have significant obstructive CAD and undergo percutaneous coronary intervention (PCI) prior to undergoing the TAVR procedure.11 As this is an elderly population, many patients have more complex CAD with severely calcified lesions, which results in a more technically challenging PCI. 7 Severe coronary calcification is considered a high-risk feature for PCI and is associated with a lower procedural success rate and higher complication rate following PCI.12-15 Technical challenges include incomplete dilation with angioplasty, increased risk of dissection, stent under-expansion or asymmetric expansion, and malapposition with consequent uneven drug distribution (which is associated with restenosis), along with longer treatment time, higher resource utilization, longer hospital stay, and overall higher PCI costs.13-21

Despite the paucity of data, many of these patients have been deemed unsuitable candidates for revascularization due to complex calcific CAD or have been incompletely revascularized with PCI prior to TAVR. Both orbital atherectomy (OA) and rotational atherectomy (RA) are established modalities for the percutaneous treatment of calcific CAD, with overall well-documented safety and efficacy.20-23 Nonetheless, due to safety concerns of hemodynamic instability, OA is not routinely used in patients with severe AS, as there is a paucity of information in the published literature about its safety in severe calcific AS. 24,25

The aim of this study was to assess the safety and feasibility of coronary OA for calcific coronary artery plaque modification in elderly patients with CAD and severe AS under consideration for a TAVR procedure.

Methods

All patients with severe AS who were under consideration for TAVR and underwent OA between September 1, 2015 and November 1, 2018 were included in this single-center retrospective study, which was conducted at an academic quaternary-care center in the United States.

The study was approved by the institutional review board and the human subjects committee. A detailed review of the electronic medical records was performed to collect the demographic, laboratory, echocardiographic, and clinical data. The study investigators manually reviewed the procedural angiograms and intraprocedural hemodynamic and electrocardiographic data to collect the predefined data points. Severity of AS was assessed by Doppler echocardiography and/or direct invasive hemodynamic measurements.

We included all patients who had severe AS per American College of Cardiology criteria and who underwent coronary OA within the study period.6 All procedures were performed using the Diamondback 360 Coronary Orbital Atherectomy System (Cardiovascular Systems, Inc [CSI]) using standard techniques at the discretion of the treating interventional cardiologist. The OA procedures were performed using the ViperWire Advance coronary guidewire (CSI) and ViperSlide lubricant (CSI) per standard protocol; intracoronary nitroglycerin was used at the discretion of the treating interventional cardiologist.

Heparin was used for periprocedural anticoagulation in all cases and all patients were pretreated with an oral P2Y12 inhibitor per standard practice for coronary interventions. Safety was measured by a composite of intraprocedural and postprocedural hemodynamic parameters and major adverse cardiac events.

Intraprocedural hemodynamic data points. Baseline systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), heart rate (HR), and need for vasopressors were abstracted. Cardiac catheterization procedural reports, hemodynamic monitoring reports, and data recorded by Mac-Lab Hemodynamic Recording System (GE Healthcare, Inc) were manually reviewed by the study investigators. Any rhythm disturbances were noted and all medications used during the procedure were recorded. Furthermore, nadir intraprocedural values for SBP, DBP, MAP, and HR were recorded.

Angiographic and clinical data points and adverse events. The study investigators (IK, AN) reviewed the recorded angiographic images and the procedural reports to collect all study data points, including device sizes, number of atherectomy burr runs, and procedural times. Angiographic stenoses and lesion characteristics before and after PCI were assessed by visual evaluation of the coronary angiograms. Adverse events, such as coronary perforation, slow-flow or no-flow (requiring intracoronary vasodilators), flow-limiting dissections, and coronary perforations were recorded. Any use of temporary pacemaker (either prophylactic or urgent) or mechanical circulatory support device placement was recorded, as were all access-site vascular complications per the Academic Research Consortium (ARC)-2 definitions. Contrast-induced acute kidney injury was defined as >0.5 mg/dL rise in creatinine or >25% rise in creatinine within 48 hours. Death during the index hospitalization and patient length of stay were recorded. Postprocedural troponin levels were not routinely obtained, per standard practice at our institution, unless clinically indicated. Myocardial infarction was defined as electrocardiographic changes of new ST-segment elevation or Q-wave formation consistent with myocardial infarction with or without chest pain or cardiac biomarker elevation when checked for chest pain or as ordered by the managing physician.

Statistical analysis. Continuous variables were reported as mean ± standard deviation and categorical variables as percentages. Comparisons of continuous variables were performed using the paired two-tailed Student’s t-test. A P-value of <.05 was considered statistically significant. All analyses were performed using SPSS software (IBM).

Results

A total of 4172 patients who underwent PCI during the study period were screened, and 217 of these patients underwent atherectomy (133 OA and 84 RA) during the index PCI procedure. Twenty-four patients meeting the study entry criteria were identified.

Baseline clinical characteristics are presented in Table 1. Patient age was 82.5 ± 7.6 years and patients were predominantly male (75%). All patients had echocardiographic evidence of severe AS (aortic valve gradient, 43.0 ± 17.7 mm Hg). Those with a gradient of <40 mm Hg were confirmed to have low-flow low-gradient severe AS by dobutamine stress echocardiography or invasive hemodynamic assessment including dobutamine infusion, per catheterization laboratory protocol. Left ventricular ejection fraction was 51.4 ± 13.6%. Echocardiographic data are presented in Table 2. All patients were on aspirin and statin therapy at baseline. The estimated risk for operative mortality of AVR and CABG was calculated using the Society of Thoracic Surgeons’ (STS) risk model to be 7.2 ± 2.1%.

Angiographic characteristics and procedural data are presented in Tables 3 and 4. Femoral arterial access was utilized in 54% of the patients, while the remainder had successful transradial PCI. Coronary artery distributions of the index lesions were as follows: left anterior descending coronary artery, 58.3%; right coronary artery, 25%; left circumflex artery, 8.3%; and left main coronary artery, 8.3%. Lesion length was 32 ± 18 mm, stented segment length was 35 ± 19 mm, and 7 patients (29%) required overlapping stents. All lesions had at least moderate-severe calcification on fluoroscopy and 19 patients (79%) had severe heavy calcification, defined as the presence of radiopacities visible without cardiac motion prior to contrast injection involving both sides of the arterial wall in at least one location, extending partially into the target lesion. Diameter stenosis was 80.8 ± 12%.

Multivessel PCI was performed in 54% of patients in the same setting (OA in >1 vessel was performed in 8.3%). The 1.25 mm Classic crown (CSI) was used in all patients, with 5.2 ± 3.3 atherectomy passes; all passes were performed at the low speed (80,000 rpm). All index lesions underwent drug-eluting stent placement post atherectomy (1.3 ± 0.5 stents). Total fluoroscopic time was 31.9 ± 16.6 min, contrast volume was 172 ± 80 mL, and radiation dose was 2437 ± 1837 mGy (air kerma). A prophylactic temporary pacemaker was placed in 8 patients (33%).

Intraprocedural hemodynamic changes, procedural complications, and clinical outcomes are presented in Tables 5 and 6. There were no statistically significant changes from baseline to intraprocedural nadir values of SBP, DBP, or MAP (all P>.05). Two patients had planned prophylactic hemodynamic support, one with Impella CP (Abiomed) left ventricular assist device and one with intra-aortic balloon pump (Getinge Group). None of the patients required vasopressors during PCI. Although there was an overall small but statistically significant drop in HR during OA (71.6 ± 12 bpm vs 63.3 ± 12.2 bpm; P=.02), only 1 patient with a pre-existing permanent pacemaker for atrial fibrillation with established conduction system disease received transient pacing from his pacemaker for a short period of time following OA of a dominant right coronary artery. None of the patients required emergent unplanned temporary pacing; temporary pacemakers were removed at the end of the procedure in all patients.

All procedures were performed under conscious sedation; none of the patients required intubation. Eight patients received intracoronary vasodilators (intracoronary nitroglycerin). No procedures were aborted. There were no instances of coronary perforation, slow-flow/no-reflow, vascular access-site complications, or contrast-induced nephropathy. One-third of patients were discharged home on the same day of the index procedure; length of stay was 2.2 ± 3.8 days. There were no procedural or in-hospital strokes. No myocardial infarctions were noted. All patients received aspirin 81 mg daily; 71% of the patients were discharged on clopidogrel 75 mg daily and 29% of the patients were discharged on ticagrelor 90 mg twice daily.

Three patients had in-hospital mortality unrelated to the PCI (1 patient developed severe hematuria that required multiple units of blood transfusion, 1 patient had a hemothorax as a complication of bedside central venous line placement during a prolonged Intensive Care Unit course eventually necessitating dialysis, and 1 patient had pulseless electrical activity arrest due to metabolic derangements with no evidence of stent thrombosis or any other coronary complications on an emergent coronary angiogram that preceded her death). TAVR was subsequently performed in 12 patients (50%) as a staged procedure. The remainder of the patients were either asymptomatic from severe AS after treatment of their CAD (n = 3), were deemed by the multidisciplinary team to have comorbidities preclusive to significant benefit from TAVR (Cohort C, n = 3), were offered but declined TAVR (n = 2) or are awaiting staged TAVR (n = 1).

Discussion

The main finding of this study is that coronary OA for calcific CAD is safe and well tolerated in elderly patients with severe AS. There are limited data regarding the best strategy for managing concomitant CAD in patients being evaluated for TAVR. There is concern that unrevascularized CAD subtending large myocardial territories may result in higher complication rates during TAVR. Most TAVR studies have excluded patients with unrevascularized CAD due to this concern.8,11 Despite this, in clinical practice, a large percentage of patients with severe calcific AS being considered for TAVR (40%-75%) have significant CAD.3,7,8 Limited data are available regarding the safety of PCI in patients with severe AS. In one of the largest such studies, Goel et al published a report on 254 patients with severe AS undergoing PCI.5 In this single-center study, which included all patients treated over a 10-year period, the authors reported a 30-day mortality rate of 4.3%, which was not significantly different from propensity-matched controls without AS. Notably, patients with a higher STS score had a significantly higher mortality rate. Although patients were not specifically excluded from this series due to heavy coronary calcification, utilization of atherectomy was not reported.

Unfortunately, the prevalence of such complex, heavily calcified lesions in elderly patients with severe AS is high.26-28 Arguably, lesions with heavy calcification are often best treated with the use of atherectomy, which results in a higher procedural success rate; outcome data are accumulating in support of using OA in calcified coronary lesions. The ORBIT II study (443 patients, 49 sites in the United States) was the pivotal study for United States Food and Drug Administration approval of the Diamondback 360 Coronary OA system for de novo severely calcified coronary lesions. OA not only helped facilitate stent delivery, but also improved both acute and 30-day clinical outcomes compared with the outcomes of historic control subjects in this difficult-to-treat patient population.23 A prospective, randomized, multicenter ECLIPSE (Evaluation of Treatment Strategies for Severe CaLcIfic Coronary Arteries: Orbital Atherectomy vs Conventional Angioplasty Technique Prior to Implantation of Drug Eluting StEnts) trial to evaluate vessel preparation using OA compared with conventional balloon angioplasty prior to stent implantation for the treatment of severely calcified coronary artery lesions is currently ongoing. The ECLIPSE trial’s co-primary endpoints are acute minimal stent area evaluated by optical coherence tomography at the conclusion of the PCI procedure in an imaging patient cohort, and 1-year target-vessel failure, including a composite of death, target vessel myocardial infarction, or ischemia-driven target-vessel revascularization.

Traditionally, interventional cardiologists have been reluctant to perform atherectomy in severe AS patients. In a recent report, Lippmann et al24 described 29 cases of successful use of coronary RA for PCI prior to TAVR, and concluded that RA-facilitated PCI can be safely performed in elderly patients with severe AS and severely calcified CAD with low risk of complications. In that cohort, there was a significant, albeit transient, drop in SBP, DBP, MAP, and HR during RA, although this was not associated with clinically significant adverse events. Despite this, there remains concern for significant hemodynamic compromise, driven by the knowledge that severe AS patients have limited cardiac reserve. During RA, distal microembolization of atherosclerotic debris can cause transient myocardial dysfunction/stunning, even amounting to cardiac biomarker leak, and some concern remains that this may be poorly tolerated in elderly patients with limited cardiac reserve due to severe AS. Furthermore, patients may develop heart block during the procedure due to RA-induced hemolysis releasing adenosine, which may also result in destabilization in patients with limited cardiac reserve. Prior studies have shown the coronary flow reserve fails to normalize following RA secondary to distal debris embolization and platelet activation.29,30 Conversely, a recently presented small study showed apparent preservation of microcirculation after OA with no significant negative impact on coronary flow reserve, with lower risk of arrhythmias and decompensation even in patients with reduced reserve.31 The proposed mechanism for these observations has been that OA permits continuous blood flow to the distal vessel with reduced bolus embolization effect, improved frictional heat dissipation, and reduced platelet activation. Of note, vessel preparation with OA has been demonstrated by optical coherence tomography to yield better stent apposition and expansion than RA, with expectant improved long-term outcomes and lower likelihood of ST.32,33

Prior to the advent of TAVR, there was no clear indication for PCI and atherectomy in patients with severe AS and calcific CAD, as they underwent SAVR with the opportunity to address the concomitant CAD by synchronous CABG. OA is a relatively novel variant of RA and provides an alternative option for effective atherectomy, yet there have been limited data in the literature regarding its safety, efficacy, and hemodynamic changes during the OA procedure in this patient subgroup.

In this study, we demonstrate that OA can be performed safely in patients with severe AS and is generally well tolerated, with no significant drop in BP or HR. There were no coronary perforations or slow-flow phenomena. Only 1 patient with pre-existing conduction disease required transient pacing from his permanent system during OA of a dominant right coronary artery. Considering the lesion length, severity of calcification, and sometimes multivessel involvement, it is evident that these were complex calcific lesions that also required multiple overlapping stents. The reduced risk of distal embolization with OA afforded the low use of intracoronary vasodilators, which could add to the instability of patients during the procedure.

The 6 Fr guide catheter compatibility of the Diamondback 360 OA system, even for the treatment of larger vessels, is reflected in the use of radial access in almost half the patients, adding further value to this approach by preserving femoral access for use during TAVR. Furthermore, radial access for PCI has been extensively demonstrated to reduce the risk of procedural complications, while still achieving plaque modification, which has been demonstrated to be safe and effective in the drug-eluting stent era. There was a statistically, but not clinically, significant small drop in HR during OA, with only 1 patient with pre-implanted permanent pacemaker needing brief pacing. Furthermore, there were no clinically significant events. All OA procedures and associated PCIs were successful, with no patients requiring vasopressors post procedure.

To our knowledge, this is the first study reporting the feasibility and safety of OA in patients with severe AS and concomitant calcific CAD. We demonstrate that this group of elderly patients tolerated the OA procedure well, with no intraprocedural or in-hospital stroke, myocardial infarction, death, or contrast nephropathy.

This study has significant clinical implications for the practicing interventional cardiologist concerned with the safety of using OA in patients with severe AS and concomitant calcific CAD. We suggest that given the compatibility of OA with 6 Fr guiding catheters, transradial PCI should be considered the gold standard in these patients, allowing operators to preserve femoral access for the planned TAVR procedure and minimize potentially catastrophic vascular complications in this high-risk patient subgroup.

Study limitations. The study has the inherent limitations of being a single-center, retrospective, single-arm study. Nonetheless, the study population reflects a real-life population with severe calcific AS, calcific CAD, and multiple comorbidities. Furthermore, the sample size, while not large, allows some early data on the safety of the OA procedure in these patients, but requires larger studies for validation. As this cohort includes few patients with severely reduced left ventricular systolic function, the safety of OA in such patients cannot be extrapolated from this study.

Conclusion

In this single-center, retrospective study, we found vessel preparation by OA to be safe and well tolerated in patients with severe AS and concomitant calcific CAD undergoing PCI. There were no significant hemodynamic or rhythm disturbances during the OA procedure, with no procedural adverse clinical events in this high-risk cohort of patients.

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From UMass Memorial Medical Center, Worcester, Massachusetts.

Disclosure: The authors have completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. Dr Kakouros reports personal fees from Philips Healthcare, St. Jude Medical, and Cardiovascular Systems, Inc; UMass principal investigator for the ECLIPSE trial. The remaining authors report no conflicts of interest regarding the content herein.

Manuscript submitted January 9, 2019, provisional acceptance given January 21, 2019, final version accepted January 25, 2019.

Address for correspondence: Nikolaos Kakouros, BSc, MBBS, MD(Res), PhD, FRCP, FACC, FSCAI, UMass Memorial Medical Center, 55 Lake Ave N, Worcester, MA 01655. Email: Nikolaos.Kakouros@umassmemorial.org

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