Surgery for small abdominal aortic aneurysms that do not cause symptoms

An aneurysm is a ballooning of an artery (blood vessel), which can happen in the major artery in the abdomen (aorta). The cause is unknown. Ruptured aneurysms cause death unless surgical repair is rapid, which is difficult to achieve. Surgery for patients with aneurysms more than 5.5 cm in diameter or who have associated pain is considered necessary to relieve symptoms and to reduce the risk of rupture and death, although there are risks with surgery. Surgical repair of the aneurysm consists of insertion of a prosthetic inlay graft either by open surgery or by endovascular repair. Small abdominal aortic aneurysms without symptoms are at low risk of rupture. They are monitored through regular imaging so that they can be surgical repaired when they subsequently become bigger.
This review identified two well-conducted, controlled trials that randomised 2026 patients with small (diameter 4.0 to 5.5 cm) asymptomatic aneurysms in the abdominal aorta to have immediate standard open repair surgery or routine ultrasound surveillance every six months. The trials did not show a meaningful difference in long-term survival between the two treatment options. The results indicate that there was no long-term survival advantage with immediate surgery compared to selective surveillance over 3.5 to 10 years follow up. Both trials showed an early survival benefit in the surveillance group because of the 30-day operative mortality with surgery. Trial participants assigned to selective surveillance were followed and surgery was performed if the aneurysm was enlarging, reached 5.5 cm in diameter, or became symptomatic. Some 62% to 75% of these participants eventually had surgical repair of the aneurysm. Neither of the identified trials enrolled a large enough number of patients to investigate possible survival differences between the treatment options for people of different age or with different sized aneurysms. There was insufficient detail to combine the published data from the two trials without having individual patient-level data.