A thoracic aortic aneurysm is a condition in which weakening of the wall of the aorta leads to a localised dilatation of the vessel. In an aortic dissection, there is leakage of blood between the layers of the vessel wall. Aneurysms and dissections may rupture, causing massive internal bleeding. Rupture of the thoracic aorta has high mortality, even with treatment.
Conventional surgery for aneurysms of the thoracic aorta involves replacing the affected part of the aorta with a synthetic graft. Aortic dissections may be managed medically or surgically, depending on the site involved and whether there are complicating features.
Endovascular stent–graft placement involves inserting a metallic stent covered with graft material inside the aorta. This is usually achieved by catheterising the femoral arteries. The stent–graft is positioned and deployed using X-ray guidance.
A systematic review of the published evidence on this procedure was commissioned by the Institute. A total of 29 studies were identified for inclusion (27 case series and two comparative observational studies).
In one comparative study, the technical success rate was 100% (67/67 patients). The overall technical success rate was 93% across 18 studies (16 case series and two comparative studies).
The rate of conversion to open repair varied from 0% (0/26 patients) to 7% (1/14 patients). The proportion of patients who experienced an increase in aneurysm size varied from 0% (0/18) to 7% (2/29) of patients. In the study with the largest number of patients, the aneurysm increased in size (by ≥5 mm) in 5% (4/84) of patients. The proportion of patients who experienced a decrease in aneurysm size varied from 100% (18/18) to 17% (5/29) of patients. For more details, see the systematic review.
The 30-day mortality rate varied from 0% (in several studies with a combined population of 94 patients) to 14% (2/14 patients). The overall mortality ranged from 3% (1/37 patients) to 24% (11/46 patients) across 17 studies with a mean follow-up of 14 months.
The most commonly reported complication following endovascular stent–graft placement was endoleak (incomplete sealing of the aneurysm). Nineteen studies reported at least one patient with an endoleak, with a mean incidence of 13% over 12 months (the total number of patients in these studies was 752; follow-up ranged from 3 to 25 months). Five studies with a total of 83 patients reported that there were no cases of endoleak during a mean follow-up period of 12 months.
Injuries to the access artery were reported in nine case series, and included iliac artery dissection in 4% (1/26) of patients, perforation of the iliac artery in 4% (1/27) and dissection/rupture of the femoral artery in 6% (2/34) of patients. One case series reported stent fracture in 13% (11/84) of patients, and six cases of stent migration were reported across 15 case series.
Other reported complications included wound complications in 25% (8/32) of patients, stroke in 19% (8/43), renal failure requiring dialysis in 11% (2/19) and paraplegia in 7% (3/43) of patients. For more details, see the systematic review.
It was noted that there was a lack of long-term data on the durability of stent–grafts.