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Natural History of Medically Managed Acute Type B Aortic Dissection | Journal Scan
Study Questions:
What are the outcomes of patients with acute type B aortic dissection (AoD-B) undergoing initial medical management in the contemporary era?
Methods:
This was a single-center study involving patients medically managed for AoD-B between March 1999 and March 2011. A total of 298 patients were identified and were followed for an average of 4.2 years (0.1–14.7). All patients presented within 14 days of onset of symptoms and had imaging confirming AoD-B. Intramural hematoma and penetrating ulcer were not included. Failure of medical therapy was defined as death or a complication of dissection requiring intervention. Early failure was defined as that occurring within 15 days of initiation of medical therapy. Primary outcomes included all-cause survival, freedom from intervention, and the composite of intervention-free survival.
Results:
Patient age was 65.9 ± 15 years and 61.7% were male. Hypertension was the most common comorbidity and was present in 72.5%. Over an average of 4 years of follow-up, there was a failure of medical therapy in 174 patients (58.4%) including 87 (29.2%) interventions and 119 (38.3%) deaths. Early failure was noted in 37 patients (12.4%) including death in 15 and intervention in 25. Dependent on date of presentation and nature of complication, intervention included an open operative approach (63 cases, 72.4% of interventions) or endovascular stent grafting. In 57 patients (66% of interventions), the indication for operation was aneurysmal degeneration defined as an absolute size >6 cm or growth >5 or 10 mm at 6 or 12 months or symptomatic aneurysm. Average time to operation for aneurysmal degeneration was 2.3 years compared to 24 days when the indication for intervention was not aneurysmal degeneration. Freedom from intervention was 77.3 ± 2.4% at 3 years and 74.2 ± 2.5% at 6 years, and was not predicted by any clinical or demographic factor. Intervention-free survival was 55.0 ± 3.0 % at 3 years and 41.0 ± 3.2% at 6 years. Only end-stage renal disease was predictive of the failure of medical therapy (hazard ratio, 2.6; p = 0.02). When comparing the subset of patients requiring intervention to those undergoing continued medical therapy, survival was similar at 3 years, but at 6 years, survival was 76.4 ± 4.7% in those having undergone intervention versus 59.3 ± 3.8% in those undergoing medical therapy (p < 0.05).
Conclusions:
The majority of patients who present with AoD-B will fail medical therapy and have a 6-year intervention-free survival of 41%. Intervention for AoD-B appears to confer a survival advantage compared to medical therapy alone.
Perspective:
This paper outlines a single-center experience with a substantial number of patients presenting with AoD-B for whom medical therapy was the initial strategy. It nicely outlines the progression of AoD-B with respect to aneurysmal degeneration or subsequent development of complications requiring intervention, and suggests a survival benefit to intervention compared to continued medical therapy. This is a retrospective review, however, and the indications for proceeding to intervention were likely varied and no randomized control group was available. The available data did not allow identification of aorta-related mortality. This manuscript does provide an excellent window on the medically treated natural history of acute type B dissection and suggests the need for a randomized trial of early intervention versus medical therapy in this patient subset. Interestingly, no clinical or demographic feature accurately predicted the need for intervention. Detailed parameters of dissection and aorta characteristics from imaging were not available, but would be an obvious target in a prospective study.
Keywords: Aneurysm, Dissecting, Aneurysm, Aorta, Aortic Aneurysm, Thoracic, Aortic Aneurysm, Cardiac Surgical Procedures, Comorbidity, Early Medical Intervention, Hematoma, Hypertension, Kidney Failure, Chronic, Retrospective Studies, Survival, Vascular Diseases
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