Evaluation of the Medtronic Exponent Self-Expanding Carotid Stent System With the Medtronic Guardwire Temporary Occlusion and Aspiration System in the Treatment of Carotid Stenosis
Combined From the MAVErIC (Medtronic AVE Self-expanding CaRotid Stent System with distal protection In the treatment of Carotid stenosis) I and MAVErIC II Trials
Background and Purpose—Embolic protection devices and improved stent technology have advanced the endovascular treatment of carotid artery disease. A combined analysis was performed of the MAVErIC (Medtronic AVE Self-expanding CaRotid Stent System with distal protection) I and II trials to evaluate the safety and feasibility of this system among patients at high risk for surgical endarterectomy.
Methods—Four hundred ninety-eight patients were enrolled in the MAVErIC I (99 patients) and MAVErIC II (399 patients) studies from June 2001 to October 2004. The results were pooled for statistical analysis of a common primary end point, the 365-day rate of major adverse events. Clinical follow-up took place at 30 days, 6 months, and 365 days postprocedure.
Results—The 365-day major adverse event rate, defined as death, stroke, or myocardial infarction within 30 days, and death, ipsilateral stroke, or myocardial infarction from days 31 to 365 was 12.5%. The incidence of neurological death through 365 days was 1.1%. The 30-day major adverse event rate was 5.4%. Subgroup analyses showed no notable differences in the 365-day major adverse event rate for symptomatic patients compared with asymptomatic patients.
Conclusion—Treatment of carotid artery disease with carotid artery stenting with a self-expanding stent and distal embolic protection results in a low 30-day adverse event rate, including the occurrence of stroke in patients at high risk for carotid endarterectomy.
Since DeBakey performed the first carotid endarterectomy (CEA) in the early 1950s,1 the procedure has dominated the treatment of carotid artery disease. CEA is superior to best medical therapy in symptomatic patients with >50% stenosis and asymptomatic patients with >80% stenosis.2–4 As an alternative, carotid artery stenting (CAS) offers a number of potential advantages over CEA, including the avoidance of general anesthesia and cervical incisions; significantly fewer complications from cranial nerve palsy, neck hematoma, and infection; and continuous monitoring of the patient’s neurological condition during the procedure.5 CAS in combination with embolic protection devices may be an alternative to surgery in patient with high risk for complication after CEA.6–12 Without embolic protection, the benefit of CAS over CEA has been questioned.13–15
The development of mechanical cerebral protection devices that prevent friable carotid plaque from embolizing to the brain is likely the major technical advancement that has made endovascular management relatively safer than CEA in regard to cerebral ischemic complications.16
The MAVErIC (Medtronic AVE Self-expanding CaRotid Stent System with distal protection In the treatment of Carotid stenosis) I and II trials were designed to assess the feasibility, safety, and efficacy of using a distal protection device in combination with a self-expanding carotid stent in patients at high risk for CEA (Supplemental Table I). This report presents the results of the pooled data from the MAVErIC I and MAVErIC II clinical trials.
Study and Design
MAVErIC I was a Phase I single-arm, open-label feasibility trial that enrolled 99 patients at 16 US study centers.17 Investigators were required to be experienced with using carotid interventional devices. All investigators were trained on the proper use of the device according to the Food and Drug Administration-approved Instructions for Use in Carotid Stenting document, and all sites were closely monitored for adherence to study procedures. MAVErIC II was a Phase II prospective, nonrandomized, consecutive registry study that enrolled 399 participants at 34 US clinical sites. Patients with a carotid artery stenosis located between the origin of the common carotid artery and the intracranial segment of the internal carotid artery were potential candidates (Table 1).
The Institutional Review Board or ethical committee of each study center reviewed and approved the protocol, and all participants signed informed consent before participation. An independent Data Safety Monitoring Board, managed by the Harvard Clinical Research Institute (Boston, Mass), reviewed safety data during the study. Harvard Clinical Research Institute also performed the statistical analyses.
Stent and Occlusion and Aspiration System
The Exponent stent (Medtronic CardioVascular, Minneapolis, Minn) is constructed of a medical-grade nickel–titanium alloy (nitinol) and is available in diameters of 6.0, 7.0, 8.0, 9.0, and 10.0 mm and in lengths of 20, 30, and 40 mm. It is compressed and mounted onto a coaxial over-the-wire delivery system with a working length of 135 cm and compatible with 0.014-inch guidewires. The GuardWire Temporary Occlusion & Aspiration System (“the system”; Medtronic) provides temporary vascular occlusion during procedures and consists of the GuardWire Temporary Occlusion Catheter, the MicroSeal Adaptor, the Export Catheter, and the EZ Flator Inflation device (Figure).
Concomitant Medical Therapy
All participants were treated with one of the following antiplatelet regimens within 24 hours before the procedure: 325 mg aspirin daily and 1000-mg ticlopidine loading dose or 325 mg aspirin daily and 300-mg clopidogrel loading dose. If ticlopidine or clopidogrel was given <12 hours before the start of the procedure, concomitant treatment with a glycoprotein IIb/IIIa inhibitor was recommended. During the procedure, patients received intravenous heparin in sufficient doses to prolong the activated clotting time to ≥250 seconds or ≥200 seconds if an intravenous glycoprotein IIb/IIIa inhibitor was administered. Postprocedure, patients continued to receive aspirin (minimum 325 mg daily indefinitely) plus either 250 mg ticlopidine twice daily or 75 mg clopidogrel daily for a minimum of 4 weeks. A longer duration of antiplatelet treatment was at the investigator’s discretion.
Distal Protection and Stenting Procedure
Selective angiography through femoral access of the targeted carotid vessel was performed with standard frontal, lateral, and oblique views to best isolate and define the full extent of the carotid lesion. Baseline stenosis severity was assessed and the reference vessel sized at appropriate locations (distal and proximal to the stenosis) to enable selection of the correct size of the stent and system components.
The occlusion balloon was positioned approximately 40 mm distal to the target lesion. Occlusion of the internal carotid artery was generally well tolerated without patient discomfort. The patient’s neurological status was monitored throughout the procedure using awareness and motor tests and assessing the patient’s ability to move the contralateral hand. Staged occlusions were allowed for patients who were intolerant of the continuous occlusion. Stents were slightly oversized to allow for an “interference” fit of 0.5 mm to 1.0 mm between the vessel and the stent for stent expansion. Only one stent was permitted for treatment of the target lesion, but multiple lesions in the target vessel could be treated with a single stent. Poststent balloon inflations were permitted to ensure optimal stent apposition and expansion. An “export catheter” was used before deflation of the occlusion balloon to aspirate any debris. Aspiration was performed according to the procedures as outlined in the Food and Drug Administration-approved Instructions for Use.
Carotid angiograms were forwarded to a central angiographic laboratory for qualitative and quantitative angiographic analysis. Lesion location was classified as contiguous (<5 mm) with the carotid bifurcation, remote (>5 mm) from the carotid bifurcation, or sequential that involves the bifurcation and second stenosis >10 mm from the more proximal lesion. The distal of the minimal lumen diameter from the carotid bifurcation was measured in millimeters. Lesion length was calculated as the distance (in millimeters) from the proximal to the distal shoulder of the lesion defined as a reduction of >20% of the reference diameter. Lesion length was classified as discrete (<10 mm in length), tubular (10 to 19.9 mm in length), or diffuse (≥20 mm in length). Haziness was defined as lucencies within the lesion. Access tortuosity was defined as the presence of >2 bends >75° to reach target lesion or one bend >90°. Distal tortuosity was defined as >2 bends >75° distal to the target lesion or one bend >90°. Eccentricity included lesion with one of its luminal edges in the outer one fourth of the apparent normal lumen. Calcification was defined as readily apparent densities noted within the apparent vascular wall at the site of the stenosis. Ulceration was defined as a lesion that had a small crater or lumen flap.
Quantitative carotid analysis was performed using a validated automated algorithm (Cardiovascular Angiography Analysis System) and a “worst view” analysis that identified the most severe projection of the stenosis. The reference diameter for the internal carotid artery (North American Symptomatic Carotid Endarterectomy Trial criteria) was defined using a 5-mm segment of the parallel portion of the internal carotid artery. The reference diameter for common carotid stenosis was determined using a 5-mm segment of the distal common carotid artery. The minimal lumen diameter was identified and the percent diameter stenosis was calculated as follows: (1−[minimal lumen diameter/reference diameter])×100. The minimal lumen diameter and percent stenosis were determined within the stent (in-stent) and within the stent and its 5-mm margin (in-lesion) analysis. The National, Heart, Lung and Blood Institute criteria were used to classify dissections after the procedure.
An electrocardiogram was required before and after the procedure and after any suspicious episodes of myocardial ischemia (Harvard Clinical Research Institute Electrocardiogram and Arrhythmia Core Laboratory, Boston, Mass). Cardiac enzymes (creatine kinase and creatine kinase-MB) were measured within 72 hours of the procedure. In cases of a postprocedural elevation in creatine kinase levels, creatine kinase and creatine kinase-MB were monitored every 8 hours for 24 hours starting with the first elevation noted.
Participants underwent clinical follow-up periprocedurally at 30 days, 6 months, and 12 months, and neurological assessments were made by means of the National Institutes of Health Stroke Scale, the Barthel Index, and the Rankin Scale. Participants then had annual clinical follow-up for a 5-year period postprocedure.
Study End Points
The primary end point in MAVErIC I and MAVErIC II was the major adverse event (MAE) rate through 1 year (365 days) postprocedure defined as the occurrence of any death, myocardial infarction (MI), or ipsilateral stroke. For consistency with other published studies of CAS, a revised MAE rate through 1 year (365 days) postprocedure was also evaluated defined as the occurrence of any death, stroke, or MI within 30 days plus any death, MI, or ipsilateral stroke from 31 days to 365 days postprocedure. This revised MAE definition was more conservative than the original primary end point in that it could potentially detect a higher rate of MAE than the protocol-defined MAE.
The secondary safety end points were the MAE rate through 30 days postprocedure and the freedom from target lesion revascularization through 1 year postprocedure. Other safety end points included the neurological MAE rate and stroke MAE rate. Protocol-specified secondary efficacy end points included freedom from stroke at 1 year postprocedure and acute lesion, device, and procedural success (see Supplemental Table III for end point definitions; available at http://stroke.ahajournals.org).
MAVErIC I was designed to include 100 participants as a feasibility study. This sample size was not intended to provide statistical evidence of efficacy of the study device. The MAVErIC II registry was designed to include 400 participants. The protocol specified analysis plan was to pool the data from MAVErIC I and II if the data from the 2 studies were comparable.
The sample size was determined based on the plan to conduct a noninferiority analysis comparing the original primary end point and the revised MAE rate with the 12-month mortality risk in patients undergoing CEA. The overall CEA 1-year mortality risk was estimated at 12.5%, a value that was calculated based on literature-reported event rates in a mix of anatomic and comorbid patients. To assess the noninferiority of the stent and the system versus CEA, 380 evaluable participants were required to reject the null hypothesis at 80% power assuming a 12.5% primary end point and a delta of 4% at an α level of 0.05.
Analysis Plan for Pooling Data
To assess the poolability of the MAVErIC I and II studies, the original primary and the revised MAEs at 1 year were evaluated. The trials could be pooled if the MAEs were not different between the trials or if the event rate was <16.5% (the level required to reject the null hypothesis). The analysis met the prespecified acceptance criteria for poolability on the analysis population.
Multiple baseline characteristics and predictor covariates were compared for MAVErIC I and II. Only age, baseline reference vessel diameter, and history of CEA differed between the 2 studies. Participants in the MAVErIC I study were younger, had larger reference vessel diameter, and were more likely to have had CEA as compared with MAVErIC II subjects. These variables were therefore included as covariates in a logistic regression analysis on the pooled sample as prespecified in the protocol.
Data analyses were performed on the intent-to-treat (ITT) population (defined as all enrolled participants) and the analysis population (defined as all enrolled participants who had at least 335 days of follow-up or had an MAE by day 365). The analysis population was the primary population for evaluation of the protocol-defined and revised primary end points for the pooled results from MAVErIC I and II.
For the primary analysis, the number and percentage of participants with any death, stroke, or MI within 30 days and any death, MI, or ipsilateral stroke from 31 days to 365 days postprocedure along with the corresponding 95% CI were analyzed for the analysis population and the ITT population. The individual components of the MAE end point were also reported separately.
For the secondary safety and efficacy analyses, the number and percentage of participants with 30-day MAE along with the corresponding 95% CI were analyzed for the ITT population. The Kaplan–Meier estimates of time to target lesion revascularization, target vessel revascularization, and stroke through 1 year, with corresponding SEs, were also analyzed for the ITT population. The number and percentage of participants with lesion success, device success, and/or procedural success, and the corresponding 95% CIs were analyzed for participants in the ITT population who had angiographic data available.
Subgroup analyses were performed on symptomatic versus asymptomatic participants. Symptomatic participants were those with a history of stroke or transient ischemic attack. The number and percentage of MAEs, through 30 days and 365 days and the corresponding 95% CIs, were analyzed for each of these subgroups within the analysis population.
Between June 2001 and October 2004, 498 participants were enrolled and underwent carotid stent placement in the MAVErIC I (99 participants) and MAVErIC II (399 participants) studies. All 498 participants were included in the ITT population and 473 participants in the analysis population. A total of 25 (5.0%) participants had no contact after the lower 365-day visit window of 335 days and were excluded from the analysis population.
The majority of participants were men, and the mean age was 73 years. Most participants (88.7%) had a history of hypertension, but only 1.7% reported a history of uncontrolled systemic hypertension (Table 2). Other commonly reported medical conditions included dyslipidemia requiring medication, peripheral vascular disease, diabetes mellitus, previous Q wave or non-Q wave MI, and clinical congestive heart failure.
Baseline quantitative carotid angiography readings were available in 97.6% of the participants. The target lesion was located in the internal carotid artery in 438 participants (90.1%) and in the common carotid artery in 48 participants (9.9%). Lesion characteristics are described in Table 3. The mean percent diameter stenosis decreased from 69.8%±10.4% to 18.6%±12.9% after stent placement. The minimal lumen diameter increased from 1.37±0.59 mm at baseline to 3.67±0.73 mm after stent placement. There were no episodes of total occlusion or abrupt closure, and there was no dissection more than National Heart, Lung and Blood Institute Type C and no flow limitations.
Primary End Point
The MAE rate through 30 days postprocedure was 5.4% (95% CI, 3.6% to 7.8%) for the ITT population (Table 4). A stroke occurred in 21 patients (4.2%) and was the most common MAE at 30 days. Of these, 17 were ipsilateral to the stent placement site, and one patient experienced an ipsilateral and nonipsilateral stroke. The rate of death and MI in the first 30 days postprocedure was 1.0% and 1.4%, respectively (Table 4). The probability of target lesion revascularization and target vessel revascularization was low through 365 days postprocedure (1.5% and 1.7%, respectively).
In the analysis population, the MAE rate through 365 days was 11.8% (95% CI, 9.1% to 15.1%), and the revised MAE rate through 365 days was 12.5% (95% CI, 9.6% to 15.8%; Table 5). The results were similar after adjusting for clinically significant variables (age, baseline reference vessel diameter, and history of CEA; 10.6% for the original MAE rate and 11.4% for the revised MAE rate). Both MAE rates were within the predetermined margin of 4% of the predetermined death and complication rate for CEA (12.5%), indicating that the stent system was noninferior to CEA.
Secondary Safety End Points
The rate of all-cause death was 8% (38 patients) and was the most common MAE reported through 365 days. The incidence of neurological death was low. The primary cause of death was cardiac in 20 patients (4.2%) and nonneurological, noncardiac in 13 patients (2.7%). The incidences of stroke and MI through 365 days postprocedure were 4.9% and 2.1%, respectively. The neurological MAE rate through 365 days was 6.1% (95% CI, 4.1% to 8.7%), and the stroke MAE rate for this time period was 5.9% (95% CI, 4.0% to 8.4%). The rate of target lesion revascularization was 1.5% (7 patients; 95% CI, 0.6% to 3%; Table 4).
Secondary Efficacy End Points
The incidence of stroke was low in this population of patients with carotid stenosis at high risk for CEA. Based on a Kaplan–Meier estimate for the ITT population, the probability of stroke at 365 days postprocedure was 4.7%. Lesion, procedural, and device success were achieved for 90.9%, 87.2%, and 85.7% of evaluable participants, respectively.
The 2-sided 95% CIs around the MAE rates for asymptomatic patients and symptomatic patients overlapped at 30 and 365 days, suggesting that there were no notable differences between these subgroups through 365 days. The MAE rate through 30 days postprocedure was 3.7% (95% CI, 1.8% to 6.7%) for asymptomatic patients (57.1% of the analysis population) and for symptomatic patients (42.9% of the analysis population) was 8.4% (95% CI, 5.0% to 13.1%). The MAE rate through 365 days was 10.8% (95% CI, 7.3% to 15.2%) for asymptomatic patients and 14.6% (95% CI, 9.9% to 20.4%) for symptomatic patients.
This report presents the combined results from 2 studies, MAVErIC I and MAVErIC II, designed to evaluate the safety and efficacy of a new stent and aspiration system for the treatment of carotid stenosis in symptomatic or asymptomatic patients who were determined to be at high risk for CEA and amenable to percutaneous treatment.
In this population, use of the stent system was associated with a safety profile consistent with that reported in other published clinical studies or registries of carotid stent systems.7,8,10,16,18–23 The Stenting and Angioplasty with Protection in Patients at High Risk for Endarterectomy (SAPPHIRE) study involved a high-risk cohort of patients with symptomatic (>50%) or severe asymptomatic (>80%) atherosclerotic carotid artery stenosis.7 In this study, CAS with the use of a distal embolic protection device was noninferior to CEA for the prevention of stroke, death, or MI among patients for whom surgery posed an increased risk (P=0.004). Furthermore, the rate of these events was 39% lower for patients who underwent protected CAS than for those who underwent CEA (P=0.053). A number of other trials, including BEACH (The Boston Scientific EPI: A Carotid Stenting Trial for High-Risk Surgical Patients),10–12 ARCHeR II (Acculink for Revascularization of Carotids in High Risk Patients),8 and CABERNET (Carotid Artery Revascularization Using the Boston Scientific FilterWire and EndoTex Nexstent),9,19 have reported similar rates of major adverse cardiac events and complications. A meta-analysis of 10 randomized controlled trials, including 3182 participants, demonstrated that CAS was not inferior to CEA in terms of death, nonfatal MI, or stroke,6,7,24–30 However, only 3 studies included in the meta-analysis used cerebral protection devices.7,28,29
The 365-day MAE rate for the pooled results of MAVErIC I and II was 12.5%. It is notable that this MAE definition was more stringent than that used in the ARCHeR studies, which reported a MAE rate of 9.6% as defined by death, stroke, or MI within 30 days and any ipsilateral stroke (in the same territory as the lesion) between 31 days and 365 days postprocedure.8 The MAVErIC I and II MAE definition was also more stringent than that used in the SAPPHIRE study, which reported a MAE rate of 12.2% (30-day death, stroke, and MI, plus 31- to 365-day death and ipsilateral stroke).7
The proportion of participants in the ITT population who experienced an MAE through 30 days in the combined MAVErIC studies was 5.4% with 4.2%, 1.4%, and 1.0% experiencing a stroke, MI, or death, respectively, by this time point. In comparison, the 30-day MAE rate in ArCHeR was 8.3%, and it was 2% in Clopidogrel and Aspirin for Reduction of Emboli in Symptomatic carotid Stenosis (CARESS).8,16 The 30-day MAE rate for these combined results was lower than that seen in the combined ARCHeR I studies (8.3%), and it is also lower than that typically reported with CEA.8
Subgroup analyses did not reveal any notable differences in the 365-day MAE rates for symptomatic patients compared with asymptomatic patients. This finding is important, because there have been insufficient data in the literature to support endovascular treatment for carotid artery disease in asymptomatic patients. The 3500-patient cohort in the CAPTURE (Carotid Acculink/Accunet Post-Approval Trial to Uncover Unanticipated or Rare Events) postmarketing study reported an overall 30-day MAE rate of 6.3%. Most of the 3500 patients included in the study were asymptomatic (86%). In the symptomatic cohort, the 30-day MAE rate was 12.0%.18
The Carotid Revascularization: Endarterectomy versus Stent Trial (CREST) is a Phase III randomized trial sponsored by the National Institute of Neurological Disorders and Stroke. It is completed with an enrollment of 2500 patients. This study will add significantly to the pool of data regarding treatment of both symptomatic and asymptomatic patients with endovascular therapy. However, the study only involves a low surgical risk cohort of patients for both symptomatic and asymptomatic carotid artery disease.31
It has been previously established that CAS with the use of an embolic protection device is a clinically appropriate alternative to CEA.7 The major risks of carotid stenting include stroke and MI with death being a possible result of either event. The global registry data reveal that the rate of stroke and procedure-related deaths has fallen from 5.29% for procedures without embolic protection to 2.23% for procedures that used embolic protection.13 Moreover, embolic filtration devices have been found to reduce the risk of cerebral ischemic events from 5.5% to 1.8%.14 The GuardWire Temporary Occlusion & Aspiration System provides distal protection through artery occlusion and debris aspiration as opposed to a distal filter system. Potential advantages of the distal balloon occlusion system over distal filters include a smaller, more flexible system that is easier to manipulate in patients with difficult anatomy. In contrast, filter systems are generally bulkier and more rigid. In addition, the balloon occlusion system is associated with more complete debris capture, thereby having a lower risk of microemboli than distal filters.32,33 The temporary interruption of cerebral perfusion is a potential disadvantage of this approach, and it may not be suitable for patients who are intolerant of continuous occlusion. The data from MAVErIC I and II demonstrated that the procedure was generally well tolerated and the cessation of cerebral perfusion did not appear to be associated with adverse clinical outcome.
These findings should be evaluated in the context of the following study limitations. This study was a nonrandomized registry, limiting the ability to compare the efficacy and safety of CAS with embolic protection and CEA. Factors that could have influenced the study outcomes may have been present that were unaccounted for in the covariate analysis.
This study adds to the data supporting CAS with the use of an embolic protection device as a clinically appropriate alternative to CEA in the high surgical risk cohort of patients. The stent and aspiration system was associated with a reduction in percent diameter stenosis and a low incidence of stroke in patients with CAS at high risk for CEA. This study also adds to the data available regarding the safety of endovascular treatment of carotid artery disease in asymptomatic patients. Further evidence of efficacy for this patient cohort will be elucidated with the conclusion of several additional large randomized trials currently underway.
MAVERIC I and II Participating Investigators and Sites:
Edward Diethrich, MD, Arizona Heart Institute, Phoenix, Ariz; William Wu, MD, Baptist Medical Center, San Antonio, Texas; Andrew Eisenhauer, MD, Brigham & Women’s Hospital, Boston, Mass; Richard Zelman, MD, Cape Cod Hospital, Hyannis, Mass; Mark Bates, MD, Charleston Area Medical Center, Charleston, WVa; James Joye, DO, El Camino Hospital, Mountain View, Calif; Robert Molnar, MD, Genesys Regional Medical Center, Flint, Mich; Gary Ansel, MD/Barry George, MD, Grant Riverside Methodist Hospital, Columbus, Ohio; Bruce Gray, DO, Greenville Memorial Hospital, Greenville, SC; Rajesh Dave, MD, Harrisburg Hospital, Harrisburg, Pa; Mike Bacharach, MD, Heart Hospital of South Dakota, Sioux Falls, SD; Jerry Miller, MD, Las Palmas Medical Center, El Paso, Texas; Sriram Iyer, MD, Lenox Hill Hospital, New York, NY; Leslie Cho, MD, Loyola University Chicago, Maywood, Ill; Andrew Eisenhauer, MD, Massachusetts General Hospital, Boston, Mass; Robert Molnar, MD, McLaren Medical Center, Flint, Mich; Mark Tannenbaum, MD, Mercy Medical Center, Des Moines, Iowa; Amit Patel, MD, Morristown Memorial Hospital, Morristown, NJ; Nicholas J. Morrissey, MD, New York Presbyterian Hospital–Columbia/Cornell, New York, NY; Elias Kassab, MD, Oakwood Hospital Medical Center, Dearborn, Mich; Stephen Ramee, MD, Ochsner Clinic, New Orleans, La; H. Bob Smouse, MD, OSF St Francis Medical Center, Peoria, Ill; Gary Ansel, MD, Riverside Methodist Hospital, Columbus, Ohio; Patrik Zetterlund, MD, Salinas Valley Memorial, Salinas, Calif; Sam DeMaio, MD, South Austin Hospital, Austin, Texas; Tom Davis, MD, St John Hospital and Medical Center, Detroit, Mich; Guy Piegari, MD, St Joseph Medical Center, Wyomissing, Pa; Zvonimir Kracjer, MD, St Luke’s Episcopal Hospital, Houston, Texas; Steve Laster, MD, St Luke’s Hospital, Kansas City, Mo; Tanvir Bajwa, MD, St Luke’s Medical Center, Milwaukee, Wis; L. Nick Hopkins, MD, State University of New York Millard Fillmore Hospital, Buffalo, NY; Frank Criado, MD, Union Memorial Hospital, Baltimore, Md; Randall Higashida, MD, University of California, San Francisco, San Francisco, Calif; Ron Fairman, MD, University of Pennsylvania, Philadelphia, Pa; Larry Wechsler, MD, UPMC Shadyside Hospital, Pittsburgh, Pa; Lowell Satler, MD, Washington Hospital Center, Washington, DC; Tony Pucillo, MD, Westchester Medical Center, Valhalla, NY; and Robert Safian, MD, and William Beaumont Hospital, Royal Oak, Mich.
Source of Funding
This study was supported by Medtronic CardioVascular, Inc, Minneapolis, Minn.
R.T.H. and J.J.P. receive research and consultant support from Medtronic.
The MAVERIC I and II trials were completed before July 2005 and therefore they not registered in a public clinical trials database.
- Received August 5, 2009.
- Revision received October 14, 2009.
- Accepted October 23, 2009.
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