Open Versus Endovascular Repair - OVER

Description:

Some recent trials such as EVAR-1 and DREAM have demonstrated that endovascular repair (EVAR) of abdominal aortic aneurysms (AAA) is associated with lower operative mortality, as compared with open repair. However, the early mortality advantage was offset by an increase in mid-term mortality. Moreover, EVAR was associated with a higher rate of complications and reinterventions. The OVER trial sought to compare mid-term outcomes in patients in the United States undergoing EVAR versus open repair for AAA repair.

Hypothesis:

EVAR would be superior to open repair in the treatment of unruptured AAA.

Study Design

Study Design:

Patients Screened: 5,161
Patients Enrolled: 881
Mean Follow Up: 1.8 years
Mean Patient Age: 70 years
Female: 1

Patient Populations:

Planned AAA repair with the following:

  • Maximum external diameter ≥5 cm
  • An associated iliac aneurysm with a maximum diameter of at least 3.0 cm
  • A maximum diameter of at least 4.5 cm plus either rapid enlargement (at least 0.7 cm in 6 months or 1.0 cm in 12 months) or saccular morphology
  • Candidate for both procedures
  • Meet manufacturer’s indications for the endovascular system that would be used if so assigned

Exclusions:

  • Previous AAA repair
  • Need for urgent repair
  • Unable or unwilling to give consent

Primary Endpoints:

  • Long-term all-cause mortality

    Secondary Endpoints:

    • Procedure failure
    • Short-term major morbidities, including MI, stroke, amputation, renal failure on hemodialysis at 1 year
    • Days in hospital and ICU after initial repair
    • Procedure-related morbidities
    • Health-related quality of life
    • Erectile dysfunction

      Drug/Procedures Used:

      Open repair involved sutured anastomoses of an anatomically placed vascular graft through an abdominal or retroperitoneal incision and was performed as usual at each participating medical center. Endovascular repair involved the transluminal introduction of an expandable graft system through the femoral or iliac arteries into the aneurysmal region of the aorta and iliac arteries to exclude the aneurysm from arterial pressure. Only endovascular systems approved by the Food and Drug Administration (FDA) were used in the study.

      Concomitant Medications:

      Aspirin (59%), beta-blockers (64%), anticoagulants (9%), and angiotensin-converting enzyme inhibitors (42%)

Principal Findings:

A total of 881 patients were randomized, 444 to EVAR and 437 to open repair. The mean aneurysm size was 5.7 cm in both arms; about 8.4% of the aneurysms were ≥7 cm in diameter, and about 43% had aneurysms <5.5 cm. About 41% had concomitant coronary artery disease, and 35% had undergone prior coronary revascularization. About 16% had a history of cerebrovascular accident, and about 17% had a history of claudication. About one-half of the patients had a low surgical risk score (53%). The intended device was either Cook Zenith (39%) or Gore Excluder (37%) in the majority of the patients.

Procedural characteristics such as duration of procedure (3.7 vs. 2.9 hours), estimated blood loss (1000 vs. 200 ml), and duration of hospital stay for initial repair (7.0 vs. 3.0 days) (p < 0.001 for all) were significantly higher in the open repair arm.

The incidence of procedure failure was similar between the open repair and EVAR arms (11.7% vs. 13.1%, p = 0.53). Overall 2-year mortality was similar between the two arms (9.8% vs. 7.0%, p = 0.13). However, 30-day mortality was significantly higher in the open repair arm (2.3% vs. 0.2%, p = 0.006). This was not affected by AAA diameter. Mortality beyond 30 days or hospitalization was similar between the two arms (6.6% vs. 6.1%, p = 0.74). Other outcomes at 1 year such as myocardial infarction (MI) (2.7% vs. 1.4%, p = 0.14) and stroke (0.9% vs. 1.6%, p = 0.38) were similar between the two arms. However, the incidence of new or worsened claudication was reduced in the open repair arm (4.6% vs. 8.3%, p = 0.02). Measures of quality of life, such as SF-36 at 2 years were similar between the two arms.

Of note, in the EVAR arm, there were 134 endoleaks in 110 patients (25%), which resulted in 21 secondary therapeutic procedures in 18 patients (4.1%). Three grafts also had to be explanted, with conversion to open repair. The most common reason for a secondary therapeutic procedure in the open repair arm was incisional hernia repair (4.9%).

Interpretation:

In this interim report of mid-term outcomes (up to 2 years) in patients with unruptured AAA, EVAR was associated with lower perioperative mortality as compared with open repair; however, mortality at 2 years was similar between the two arms. In addition, procedure time and length of hospital and intensive care unit (ICU) stay were shorter in the EVAR arm.

The results of this trial with respect to reduced perioperative mortality with EVAR are similar to those noted in DREAM and EVAR-1. However, both those trials also noted a higher incidence of mid-term mortality with EVAR, which was not demonstrated in this trial. Differences in inclusion criteria, size of aneurysms treated, and type of device used could explain some of these differences. Longer-term outcome data are awaited to fully assess differences between the two procedures.

References:

Lederle FA, Freischlag JA, Kyriakides TC, et al. Outcomes following endovascular vs open repair of abdominal aortic aneurysm: A randomized trial. JAMA 2009;302:1535-42.

Clinical Topics: Cardiac Surgery, Heart Failure and Cardiomyopathies, Invasive Cardiovascular Angiography and Intervention, Vascular Medicine, Aortic Surgery, Cardiac Surgery and Heart Failure, Interventions and Coronary Artery Disease, Interventions and Vascular Medicine

Keywords: Blood Vessel Prosthesis Implantation, Coronary Artery Disease, Stroke, Intensive Care Units, Myocardial Infarction, Endovascular Procedures, Arterial Pressure, Iliac Artery, Peripheral Vascular Diseases, Length of Stay, Endoleak, Iliac Aneurysm, Quality of Life, Aortic Aneurysm, Abdominal, Herniorrhaphy


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