The goal of this clinical trial is to determine whether an upfront invasive strategy of TEVAR plus medical therapy reduces the occurrence of a composite endpoint of all-cause death or major aortic complications compared to an upfront conservative strategy of medical therapy with surveillance for deterioration in patients with uncomplicated type B aortic dissection.

The study will be a prospective, pragmatic, randomized clinical trial of the comparative effectiveness of an initial strategy for the treatment of uncomplicated type B aortic dissection (uTBAD). Patients with uTBAD and no prior history of aortic intervention will be randomized within 48 hours to 6 weeks after index admission to one of the two initial strategies. Follow-up will be ascertained via a centralized call center and ascertainment of medical records, as well as remote blood pressure monitoring. Recommendations regarding medical therapy will be made to enrolling centers and feedback on the quality of medical care given, however, all subsequent care, with the exception of aortic interventions, will be at the discretion of the responsible clinical care team. Aortic interventions will allowable only as per protocol.

Inclusion Criteria:

1. Age > 21 years
2. Patients with a Stanford type B aortic dissection not involving the aorta at or proximal to the innominate artery, without rupture and/or malperfusion syndrome (renal, mesenteric, or extremity) who are within 48 hours to 6 weeks after start of index admission for their type B dissection
3. Ability to provide written informed consent
4. Investigator believes anatomy is suitable for TEVAR

Exclusion Criteria:

1. Ongoing systemic infection
2. Pregnant or planning to become pregnant in the next 3 months
3. Life expectancy related to non-aortic conditions < 2 years
4. Unwilling or unable to comply with all study procedures
5. Known patient history of genetic aortopathy
6. Penetrating Aortic Ulcer without concomitant uTBAD
7. Intramural hematoma without concomitant uTBAD
8. Iatrogenic (traumatic) aortic dissection

The Statistical and data analytic center (SDCC) will submit to the NHLBI data repository de-identified Limited Access Datasets (LADs) and associated documentation, for use by other investigators. The LADs and documentation will be submitted within 2 years after publication of the primary results manuscript. Documentation will include copies of the case report forms; a list of derived variables and the formulas used to create them; and a codebook providing for each variable the variable name, coding conventions, and distribution of values. It will also include a list of data modifications made when creating the LAD, and a copy of the informed consent template, so that future use of the data will be consistent with the consent provided by the study subjects.The goal is to make data available to other investigators while protecting the rights and privacy of the subjects who participated in the studies. The SDCC will anonymize the datasets.

2 years

The methods for restricting access will also need to be determined, either with password access and/or with executed Data Agreements. Related to the restricted use of data is the need to specify appropriately in informed consent forms that the study participant's de-identified data may be made available to other researchers.