RS12 - Aortic Instability in Medically Managed Acute and Subacute Type 3B Aortic Dissections

Objectives: Aortic remodeling of both the thoracic and visceral aorta following endovascular repair of Type B aortic dissections has been well documented, but less is known about aortic growth patterns in medically managed dissections. This study aims to investigate aortic behavior in medically managed acute or subacute Type 3B dissections and identify potential associations with outcomes.

Methods: A single-center retrospective review was performed of all patients between 2010-2020 with acute and subacute non-traumatic DeBakey 3B aortic dissections that were intentionally medically managed for at least 30 days. Short-axis centerline measurements of the true/false lumen and total aortic diameter (TAD) were taken at standardized locations relative to aortic anatomy within each aortic zone, including non-dissected zones. Measurements were taken at the time of diagnosis and at six subsequent yearly intervals. Diameter changes over time were evaluated using repeated measures mixed effects linear growth modeling. Aortic instability was classified by growth in TAD≥5mm in either the thoracic (Thoracic Segment Instability [TSI], Zone 0-4) or visceral segments (Visceral Segment Instability [VSI], Zone 5-9).

Results: A total of 78 patients were identified and mean follow-up was 4.3±3.3 years, with 31% of the cohort having follow-up past 5 years. For the entire cohort, mean thoracic growth was 2.0±2.0 mm/year and visceral growth 2.5±2.4 mm/year, with 65% of patients demonstrating TSI and 57% demonstrating VSI within 6 years after dissection diagnosis. (Table 1). When present, TSI emerged on average within the first year, while VSI occurred with a mean between 1-2 years following dissection. Repeat measures growth modeling identified significant predictable linear growth in all aortic zones except for the non-dissected Zones 0-2 (Figure 1). Odds for TSI are significantly increased in patients with genetically triggered aortic conditions (GenTACs) (OR 2 [1.8-4.5], p=0.044) and dissections with multiple false lumens (OR 7.6 [2.2-12.3], p=0.017). In adjusted regression analysis, odds for thoracic intervention were significantly increased in patients with rapid TSI in Zone 3 (OR 3.6 [1.1-8.4], p=0.045). Similarly, odds for visceral intervention were significantly increased in patients with Zone 9 VSI (OR 9.3, [1.1-13.3], p=0.014).

Conclusions: Aortic instability was present in the majority of medically managed patients evaluated. Significant linear growth in aortic diameter occurred in zones 3-9, and odds for instability appear to be increased in GenTAC patients and those with complex dissection anatomy. Growth in zone 3 and zone 9 increased odds for thoracic and visceral interventions, respectively.