Should endovascular surgery lower the threshold for repair of abdominal aortic aneurysms?

Purpose: Because endovascular repair of abdominal aortic aneurysms (AAAs) i s less invasive, some investigators have suggested that this increasingly p opular technique should broaden the indications far elective AAA repair. Th e purpose of this study was to calculate quality-adjusted life expectancy r ates after endovascular and open AAA repair and to estimate the optimal dia meter for elective AAA repair in hypothetical cohorts of patients at averag e risk and at high risk. Methods: A Markov decision analysis model was used in this study. Assumptio ns were made on the basis of published reports and included the following: (1) the annual rupture rate is a continuous function of the AAA diameter (0 % for <4 cm, 1% for 4.5 cm, 11% for 5.5 cm, and 26% for 6.5 cm); (2) the op erative mortality rate is 1% for endovascular repair (excluding the risk of conversion to open repair) and 3.5% for open repair at age 70 years; and ( 3) immediate endovascular-to-open conversion risk is 5%, and late conversio n rate is 1% per year. The main outcome measure in this study was the benef it of AAA repair in quality-adjusted life years (QALYs). The optimal thresh old size (the AAA diameter at which elective repair maximizes benefit) was measured in centimeters. Results: The benefit of endovascular repair is consistently greater than th at of open repair, but the additional benefit is small-0.1 to 0.4 QALYs. Fo r men in average health with gradually enlarging AAAs with initial diameter s of 4 cm, endovascular surgery reduces the optimal threshold diameter by v ery little: from 4.6 to 4.6 cm (no change) at age 60 years, from 4.8 to 4.7 cm at age 70 years, and from 5.1 to 4.9 cm at age 80 years. for older men in poor health, endovascular surgery reduces the optimal threshold diameter substantially (8.1 to 5.7 cm at age 80 years), but the benefit of repair i n this population is small (0.2 QALYs). Conclusion: For most patients, the indications for AAA repair are changed v ery little by the introduction of endovascular surgery. Only for older pati ents in poor health does endovascular surgery substantially lower the optim al threshold diameter for elective AAA repair.