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INvestigation of STEnt grafts in Aortic Dissection - INSTEAD
Description:
Patients with uncomplicated type B dissections are traditionally treated with aggressive medical therapy, including tight control of hypertension. The current trial sought to evaluate the role of thoracic endovascular aortic repair (TEVAR) in the management of these patients, as an adjunct to medical therapy.
Hypothesis:
TEVAR would be superior to medical therapy alone in the long-term management of patients with uncomplicated type B dissections.
Study Design
Study Design:
Patients Screened: 597
Patients Enrolled: 140
NYHA Class: II (21%), III (4%)
Mean Follow Up: 2 years
Mean Patient Age: 60.2 years
Female: 14
Patient Populations:
- Uncomplicated type B dissection between 2 and 52 weeks after onset
Exclusions:
- Traditional indications for open or endovascular surgery (diameter ≥6 cm), with recurrent acute complications
- Anatomy unsuitable for TEVAR
Primary Endpoints:
- All-cause mortality at 2 years
Secondary Endpoints:
- Aorta-related mortality at 2 years
- A composite endpoint of progressive aortic pathology (including crossover/conversion or additional endovascular or open surgery for rupture, expansion, or malperfusion)
- Morphological evidence of aortic remodeling
Drug/Procedures Used:
Patients were randomized to either TEVAR using TALENT stent grafts (Medtronic, Inc., Santa Rosa, CA) with optimal medical therapy (OMT) or OMT alone. The stent grafts were used to scaffold ≤20 cm of dissected aorta and to seal major arteries.
Principal Findings:
A total of 140 patients were randomized, 72 to TEVAR + OMT, and 68 to OMT alone. Baseline characteristics were fairly similar between the two arms. About 83% of the patients had evidence of atherosclerosis or hypertension, and about 22% of the patients were current smokers. About 15% of the patients were classified as being American Society of Anesthesiology class III (severe systemic disease). The mean maximum diameter of the dissected aorta was 44 mm), and about 91% of the dissections had evidence of thoracoabdominal extension. About 65% of the patients in each arm had a perfused false lumen. The median time to randomization after dissection was 43 days.
TEVAR was successfully conducted in 70/72 patients, with no intraprocedural conversion to open surgery. About 17% of the patients needed two or more grafts. The median length of stay was 8 days. Periprocedural adverse events included retrograde type A dissection in one patient, and rupture of iliac access vessel in one patient. There were two deaths. About 16% of the patients in the OMT group crossed over to TEVAR over the course of follow-up.
Survival probability at 2 years was 88.9% with TEVAR and 95.6% with OMT alone (p = 0.15). Aorta-related survival was also similar between the two arms (94.4% vs. 97.0%, p = 0.44). The incidence of a cumulative endpoint of aorta-related death, crossover/conversion for expansion, and ancilliary procedures was similar between the two arms as well (p = 0.65). Complete false lumen thrombosis at the end of 2 years was significantly higher in the TEVAR arm (91.3% vs. 19.4%, p
Interpretation:
The results of the INSTEAD trial indicate that TEVAR in addition to OMT is not superior to OMT alone in the management of patients with stable uncomplicated type B dissections, despite a greater likelihood of complete false lumen thrombosis with TEVAR. This suggests that OMT, with special emphasis on strict blood pressure control, should be first-line therapy for these patients, with TEVAR being a reasonable alternative in patients with progressive expansion or late malperfusion.
References:
Nienaber CA, Rousseau H, Eggebrecht H, et al. Randomized comparison of strategies for type B aortic dissection. The INvestigation of STEnt grafts in Aortic Dissection (INSTEAD) trial. Circulation 2009;120:2519-28.
Keywords: Blood Vessel Prosthesis Implantation, Follow-Up Studies, Aortic Aneurysm, Thoracic, Atherosclerosis, Thrombosis, Probability, Hypertension, Stents
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