Aortic aneurysm

Rupture of an abdominal aortic aneurysm (AAA) usually is fatal. When treatable, prophylactic open surgical repair usually is undertaken. The 30-day mortality rate of this major surgery ranges from 4 to 12 percent. During the past decade, endovascular techniques have been developed that insert a graft through the femoral arteries to form a new endovascular surface that relieves pressure on the diseased aortic wall. Thirty-four surgical facilities in the United Kingdom participated in a randomized controlled trial comparing 30-day mortality of patients who underwent endovascular aneurysm repair (EVAR) with open repair of AAA.

Between September 1999 and December 2003, 1,082 eligible patients consented to participate in the trial. Patients were selected based on a demonstrated aneurysm of 5.5 cm (2.2 in) or more in diameter that was suitable for repair by either technique. Patients were required to be at least 60 years of age and medically fit for surgery. Facilities were encouraged to conduct surgery within one month of randomization.

The 543 patients randomized to EVAR were comparable with the 539 randomized to open repair in all significant variables. Men comprised 91 percent of each group, and the average age was 74 years. The average diameter of the aneurysm was 6.5 cm (2.6 in) in each group. Current smokers comprised 21 and 22 percent, and past smokers comprised 68 and 70 percent of each group, respectively. Groups were similar in use of aspirin (54 and 52 percent), statin use (33 and 34 percent), mean blood pressure (148/82 and 147/82 mm Hg), and identical in body mass index (26.4 kg per [m.sup.2]). Of those allocated to EVAR, 512 underwent the procedure, 15 underwent open repair, and the remaining patients died before surgery or refused or postponed surgery. For open repair, 496 underwent the procedure, 17 had EVAR, and the remainder died or refused or postponed surgery. The patients were followed for 30 days after surgery, and mortality was reported by intention to treat and by procedure undertaken.

The 30-day mortality by intention to treat was 1.7 percent (nine patients) for EVAR compared with 4.7 percent (24 patients) for open repair. This difference remained statistically significant after adjustment for age, sex, aneurysmal diameter, statin use, renal function, and time from randomization to surgery. Patients in the EVAR group had a shorter hospital stay, with a mean of seven days compared with 12 days for open repair, but this was not statistically significant. The mean operating time also was shorter (180 compared with 200 minutes), but the difference did not reach statistical significance. Secondary interventions during primary admission or up to 30 days after surgery, such as re-exploration, correction of leakage, or additional surgeries, were undertaken in 52 EVAR patients (9.8 percent) compared with 30 (5.8 percent) in the open repair group. In the per-protocol analysis, EVAR reduced in-hospital mortality by three fourths and the mortality rate at 30 days by two thirds.

The authors conclude that EVAR was associated with a short-term (30-day) mortality advantage. While these results are encouraging, they may not endure over a longer follow-up period. Studies of the morbidity and mortality of patients undergoing the two procedures are ongoing.

ANNE D. WALLING, M.D.

Greenhalgh RM, et al. Comparison of endovascular aneurysm repair with open repair in patients with abdominal aortic aneurysm (EVAR trial 1), 30-day operative mortality results: randomised controlled trial. Lancet 2004;364:843-8.

EDITOR'S NOTE: The authors of this study are careful to recommend against any substantial change in current selection of technique for repair of abdominal aortic aneurysm until more data are available on longer term outcomes of endovascular aneurysm repair (EVAR). Preliminary data from a European study indicate an annual mortality of more than 1 percent attributed to graft failure following EVAR. (1) Even in the short-term, results reported by the EVAR group, the higher rate of reinterventions is worrying and could indicate an increased risk of endoleaks and other graft failures in the EVAR procedure. As stated in an accompanying editorial, (2) the costs and outcomes of the two techniques could prove to be highly similar.

REFERENCES

(1.) Harris PL, Vallabhaneni SR, Desgranges P, Becquemin JP, van Marrewijk C, Laheij RJ. Incidence and risk factors of late rupture, conversion, and death after endovascular repair of infrarenal aortic aneurysms: the EUROSTAR experience. J Vasc Surg 2000;32:739-49.

(2.) Lindholt JS. Endovascular aneurysm repair [Editorial]. Lancet 2004;364:818-20.

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