The purpose of this study is to compare endoluminal stent grafting with the GORE TAG device and Best Medical Therapy (BMT) to BMT alone in the treatment of acute uncomplicated type B aortic dissections.

Dissection of the aorta is a medical emergency requiring immediate surgery. Type B dissections are typically treated with surgery or endoluminal therapy when complications such as uncontrollable pain, organ ischemia, or aortic rupture are present. However, the treatment of patients with uncomplicated, acute type B dissections is controversial. Best medical therapy (BMT) is the standard of care in these cases since surgical repair offers no additional survival advantage. However, Endoluminal stent graft therapy with the GORE TAG Thoracic Endoprosthesis (GORE TAG device) may offer distinct advantages as an adjunct to medical therapy for uncomplicated acute type B dissection. The goal of endoluminal stent grafting is to cover the primary entry tear of the dissection to isolate the false lumen from blood flow and induce aortic remodeling.

Inclusion Criteria:

1. Presence of acute uncomplicated type B aortic dissection
2. Able to tolerate endotracheal intubation and general anesthesia
3. Maximum transverse diameter of the descending thoracic aorta < 55 mm and absence of descending thoracic aortic aneurysm, regardless of etiology.
4. Arterial anatomy is appropriate for stent graft therapy

Exclusion Criteria:

1. ASA classification = V
2. Severe renal insufficiency defined as SVS risk renal status = 3
3. Severe respiratory insufficiency defined as SVS risk pulmonary status = 3
4. Presence of connective tissue disease
5. Active infection or active vasculitides
6. Positive pregnancy test
7. Participation in another medical research study within 3 months of study enrollment
8. Myocardial infarction or cerebrovascular accident within 6 weeks prior to study enrollment
9. Planned concomitant surgical procedures (other than left subclavian artery transposition or bypass), or major surgery within 30 days of study enrollment
10. History of drug abuse