Background
Over the last decade, considerable advancements have been made with endovascular stent grafts for the treatment of abdominal aortic aneurysm (AAA). Early studies with endovascular aortic repair (EVAR) demonstrated significantly lower perioperative morbidity and mortality rates compared to open surgical resection [1]. Consequently, EVAR has rapidly become the standard of care for AAA repair at most centers. Studies with latest-generation stent grafts have focused on improving treatment durability and expanding EVAR eligibility to accommodate patients with challenging aortoiliac anatomy. Despite this recent progress, considerable opportunity exists to further improve the efficiency of EVAR, which may yield even better patient outcomes and lower perioperative treatment costs.
Typical EVAR cases involve vascular access via surgical exposure of the common femoral artery, general anesthesia, a 24-h intensive care unit (ICU) stay, and a 3-day hospitalization [2], all of which increase morbidity and significantly contribute to the total cost of EVAR. In the current economic climate, there is heightened scrutiny on health care resource utilization such that opportunities for improved surgical- and hospital-related efficiency must continue to be explored. Fast-track hospital care pathways have been adopted with increasing frequency for open aortic surgery, resulting in shorter ICU [3, 4] and hospital [5, 6] stays with reductions in morbidity [3, 4, 6] compared to traditional surgical practices. However, experience with fast-track EVAR remains limited. The common premise of fast-track EVAR includes well-selected patients with low-risk of periprocedural complications, bilateral percutaneous vascular access, and regional anesthesia with or without conscious sedation, all of which enable faster patient recovery and expedite hospital discharge. The largest study of fast-track EVAR involved 915 patients treated with bilateral percutaneous access and local anesthesia/conscious sedation [7]. Treatment success was achieved in 94 % of cases, mean hospital stay was 1.3 days, and 30-day mortality was only 0.6 %. The clinical and cost benefits associated with fast-track EVAR are potentially substantial, but currently are not well characterized. The Least Invasive Fast-Track EVAR (LIFE) registry was developed to explore the clinical utility and cost effectiveness of a defined fast-track EVAR protocol in patients undergoing elective AAA repair.
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Methods/Design
The LIFE registry is a prospective, nonrandomized, multicenter post-market study that will enroll 250 patients at up to 40 sites in the United States. The protocol for this clinical trial has been approved by the institutional review board (IRB) at each participating site. Recruitment is ongoing and additional sites, up to 40 total sites, will be added to those already named in Table 1. All patients provided informed consent before study participation. Patient enrollment began in October 2014. This study was prospectively registered at www.clinicaltrials.gov (NCT02224794).
Table 1
Study Sites and Institutional Review Board
Site Name | Institutional Review Board |
|---|---|
Central Arkansas Veterans Healthcare System | Central Arkansas Veterans Healthcare System IRB |
NCH Healthcare Systems | NCH IRB |
Temple University Hospital | WIRB |
Wellmont Holston Valley MC | Wellmont Health System IRB |
Morton Plant Hospital | BayCare Health System IRB |
Swedish Heart and Vascular | WIRB |
Bend Memorial Clinic | WIRB |
Hartford Hospital | Hartford Health Care IRB |
WVU Hospital | West Virginia University IRB |
St. Luke’s Episcopal Hospital | BRANY IRB |
Palomar Medical Center | WIRB |
SIH Memorial Hospital | SIH IRB |
Sutter Memorial Hospital | WIRB |
Chandler Regional Medical Center | East Valley Regional IRB |
Syracuse VA Medical Center | Syracuse VAMC IRB |
Southern Ohio Medical Center | Southern Ohio Medical Center IRB |
Jersey Shore University Medical Center | WIRB |
St. Joseph Mercy Oakland | St. Joseph Mercy IRB |
Phoenix St. Luke‘s Medical Center | WIRB |
Medical University of South Carolina | MUSC IRB III |
OhioHealth Research Institute | WIRB |
Arizona Heart Institute | WIRB |
Heart Hospital of New Mexico | WIRB |
Tuscon Medical Center | WIRB |
Harrison Medical Center | WIRB and Harrison Medical Center IRB |
Bakersfield Heart Hospital | WIRB |
Saint Jospeh Hospital | WIRB |
Lutheran Medical Center | Lutheran Medical Center IRB |
Middlesex Hospital | Middlesex Hospital IRB |
Sacred Heart Hospital | Sacred Heart Clinical IRB |
Memorial Hospital of Jacksonville (FCCI) | WIRB |
Gwinnett Medical Center | WIRB |
Scottsdale Healthcare-Osborn | WIRB |
Northern Michigan Regional Hospital | WIRB |
Participants
Eligible patients are adults with AAA requiring elective intervention who have anatomy suitable for endovascular repair. Complete inclusion and exclusion criteria are reported in Table 2. Pre-treatment assessments will include medical and surgical history, laboratory tests for creatinine and pregnancy, spiral contrast-enhanced computed tomography, and questionnaires related to groin pain severity and health-related quality of life. Patients will be enrolled and treated with EVAR if the investigator determines that bilateral percutaneous access, avoidance of general anesthesia and ICU stay, and next-day hospital discharge are feasible based on medical history and aortoiliac anatomy. Following enrollment, patients will remain in the study regardless of whether all components of the fast-track program are completed. Patient outcomes will be recorded through hospital discharge and at the 30-day follow-up visit per the schedule of activities in Table 3.
Table 2
Main study entry criteria
Main inclusion criteria |
− Age ≥ 18 years |
− Male or non-pregnant female |
− Candidate for elective open surgical AAA repair |
− AAA >5.0 cm diameter, increased ≥ 0.5 cm diameter in last 6 months, or maximum diameter > 1.5x adjacent non-aneurysmal aorta |
− Suitable anatomy for endovascular repair with the Ovation Prime Stent Graft |
− Suitable anatomy to allow Perclose ProGlide Suture-Mediated Closure System via the pre-close technique |
Main exclusion criteria |
− Dissecting or acutely ruptured AAA |
− Acute vascular injury |
− Prior AAA or iliac artery repair |
− Mycotic AAA or active systemic infection |
− Unstable angina |
− Unstable peripheral artery disease with critical limb ischemia |
− Congestive heart failure |
− Myocardial infarction or stroke within the past 3 months |
− Need for renal artery coverage (e.g. Chimney graft) |
− Planned adjunctive devices (e.g. renal stent) |
− Major surgery or interventional procedure within the past 30 days |
− Connective tissue disease (e.g. Marfan’s or Ehler’s–Danlos syndrome) |
− History of bleeding disorder or refuses blood transfusions |
− Dialysis-dependent renal failure or serum creatinine >2.0 mg/dl |
− Morbid obesity (BMI ≥40 kg/m2) |
− Home oxygen use |
− Patient admitted from skilled nursing facility |
− Life expectancy < 1 year |
− Anticipated inability to discharge patient within 1 day |
− Participation in investigational device or drug clinical trial |
− Intolerance/hypersensitivity to anticoagulation, contrast media, or stent graft components |
Table 3
Schedule of study activities
Procedure | Baseline | Procedure | Post-Procedure | 1 Month |
|---|---|---|---|---|
Medical/surgical history | X | |||
Spiral contrast-enhanced CT | X | X | ||
Laboratory assessment (creatinine, serum pregnancy) | X | |||
Quality of life (EQ-5D) | X | X | ||
Groin pain (Wong-Baker FACES Pain Rating Scale) | X | X | X | |
Endovascular AAA repair | X | |||
Adverse events | X | X | X | |
Assessment of ambulation and normal diet | X |
Device
The endograft under study is ideally suited for use in a fast-track EVAR program. The Ovation Prime stent graft is characterized by a tri-modular design with the aortic body delivered via a flexible hydrophilic-coated 14 Fr OD catheter, the smallest profile of any currently commercially available stent grafts. The aortic body is comprised of a low permeability PTFE graft and a suprarenal nitinol stent with integral anchors to achieve active fixation to the aortic wall. The aortic body contains a network of inflatable channels and sealing rings that are filled during deployment with a low viscosity, radiopaque fill polymer that cures in situ to create a conformable seal to the aortic neck. The Ovation Prime iliac limbs are comprised of highly flexible nitinol stents encapsulated in low-permeability PTFE that are packaged in ultra-low profile 13-14F OD delivery system.
Outcomes
The primary endpoint of the LIFE registry is the incidence of major adverse events through 30 days follow-up. Major adverse events are defined as any of the following events: death, myocardial infarction, stroke, renal failure, respiratory failure, paralysis, bowel ischemia, or procedural blood loss ≥ 1000 cc. All adverse events will be adjudicated by a Clinical Events Committee (CEC). Secondary endpoints of the LIFE registry include operative details, technical success, procedure- and device-related complications, patient convalescence, and ability to successfully complete all components of the fast-track protocol (Table 4). Patients will be followed in the LIFE registry for 30 days post-treatment and will undergo lifelong surveillance thereafter. A 30-day primary endpoint is appropriate since the benefits of a fast-track EVAR program are anticipated to be realized entirely in the perioperative period.
Table 4
Secondary endpoints
− Serious and non-serious adverse events |
− Access technical success (i.e. procedure successfully completed with bilateral percutaneous access) |
− Treatment success (i.e. successful completion of least invasive protocol through discharge) |
− Blood loss, including if transfusion required |
− Percent of procedures completed without general anesthesia |
− Anesthesia time |
− Procedure time |
− Contrast volume |
− Fluoroscopy time |
− Time to hemostasis |
− Time to ambulation |
− Time to normal diet |
− Groin pain |
− Quality of life |
− Percent of subjects discharged without ICU admission |
− Length of ICU stay, if required |
− Length of hospital stay |
− Percent of subjects discharged within only one overnight stay |
− Freedom from type I & III endoleak |
− Freedom from AAA rupture |
− Freedom from conversion to open repair |
− Freedom from AAA-related secondary interventions |
− Freedom from mortality |
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Hypothesis
The primary hypothesis of the LIFE registry is that the incidence of major adverse events through 30 days will be less than a target performance goal (TPG) of 10.4 %. The TPG was determined by using the 95 % upper-bound confidence interval of the 30-day major adverse event rate in the Ovation® pivotal trial (5.4 %) [8] and adding a 5 % margin.
Statistical methods
The sample size for the LIFE registry was determined using the exact binomial method based on a one-sided 5 % significance level, an anticipated 5 % major adverse event rate, and no more than 20 % attrition. Based on these assumptions, a sample size of 250 subjects provides at least 87 % power to test the primary hypothesis. Intent-to-treat analyses will be performed, which include all patients enrolled in the registry regardless of whether the fast-track protocol is completed successfully. Subjects will be considered enrolled when the delivery catheter is inserted into the vasculature. Continuous data will be reported using mean and standard deviation or median, minimum, and maximum, depending on normality assumptions. Categorical data will be reported with counts and percentages. The incidence of major adverse events will be compared to the TPG by calculating a one-sided 95 % Wilson upper confidence interval limit. Subgroup analyses will be performed for: a) patients who complete the fast-track EVAR protocol, b) patients who undergo bilateral percutaneous access but do not complete the fast-track EVAR protocol, and c) patients who do not undergo bilateral percutaneous access.
Study progress
The first patient in this study was enrolled in October 2014 and enrollment is anticipated to continue through mid-2016. As of October 4, 2015, 149 patients have been enrolled at over 25 sites in the United States.
Discussion
The recent development of ultra low-profile stent grafts enables EVAR using least invasive methods. However, strict patient selection criteria are crucial to improving outcomes of a fast-track EVAR program. Ideal candidates have access vessels free of heavy calcification or extreme tortuosity and have no major risk factors for prolonged procedure or hospitalization such as ruptured AAA, renal failure, and severe comorbid conditions. Bilateral percutaneous vascular access results in higher technical success, less blood loss, fewer complications, and shorter hospital stay compared to surgical cutdown [7, 9‐15]. Avoidance of general anesthesia is associated with lower rates of mortality and morbidity and shorter intensive care unit and hospital stays compared to regional anesthesia [16]. Next-day hospital discharge with no ICU stay has obvious cost benefits, provided that patient safety is not compromised. The observed advantages of each separate component may potentially yield synergistic clinical and cost benefits when utilized collectively in a structured fast-track EVAR protocol. The results of the LIFE study with the Ovation Prime stent graft are anticipated to be available in late 2016.
Acknowledgements
The authors thank Larry E. Miller, PhD for editorial assistance and critical review.
Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.
Competing interests
Zvonimir Krajcer, MD is an interventional cardiologist at Texas Heart Institute in Houston, Texas. He is Co-Director, Peripheral Vascular Disease Service at Texas Heart Institute, affiliated with CHI St. Luke’s Health - Baylor St. Luke’s Medical Center, and a Clinical Professor at Baylor College of Medicine. He has disclosed that he is a paid consultant to TriVascular and National Principal Co-Investigator of the LIFE study.
Venkatesh G. Ramaiah, MD, FACS, is a vascular surgeon at the Arizona Heart Institute and Hospital in Phoenix, Arizona. He is Director of Research at the Arizona Heart Institute and Medical Director of the Arizona Heart Hospital. He has disclosed that he is a paid consultant to TriVascular and National Principal Co-Investigator of the LIFE study.
Meredith Huetter leads the Medical Affairs organization at TriVascular, Inc. TriVascular is the study sponsor for the LIFE study.
Authors’ contributions
ZK, VR, and MH were involved in the conception and design of the study, equally participated in drafting the manuscript, and provided final approval for publication.