Predictors of Stable Aortic Dimensions in Medically Managed Acute Aortic Syndromes

Background: We aimed to identify predictors of stable aortic dimensions in medically managed type B aortic dissections (TBAD).Methods: Medically managed TBAD patients from the International Registry of Acute Aortic Dissection with available aortic measurements at up to 24 months were included. Growth rate was calculated by dividing the largest descending diameter at the latest end point not influenced by intervention minus initial descending diameter, by the recorded time interval. Patients were split into 2 groups: without aortic growth (<0.0 mm/year, group I) and with aortic growth (>0.0 mm/year, group II).Results: 219 patients had available data for our inclusion criteria and comprised group I (n = 89, 40.6%) and group II (n = 130, 59.4%). Mean expansion rate of the total cohort was 0.19 +/- 0.81 cm, mean expansion rate in group I was -0.47 +/- 0.54 cm, and in group II, it was +0.63 +/- 0.64 cm. Patients in group I were more frequently of Asian descent (15.9% vs. 3.1%, P = 0.001), showed more often intramural hematoma on imaging (57.3% vs. 30.0%, P < 0.001) and demonstrated complete false lumen thrombosis more frequently (25.0% vs. 9.9%, P = 0.009). Group II patients were more Caucasian (77.3% vs. 92.2%, P = 0.002), presented more with posterior chest pain (57.8% vs. 74.7%, P = 0.025), back pain (68.2% vs. 80.2%, P = 0.046), a visible double lumen (50.6% vs. 63.8%, P = 0.050), dissection originating from the left subclavian artery (51.2% vs. 68.5%, P = 0.011), and a completely patent false lumen (37.5% vs. 62.4%, P = 0.002). Mortality rates between groups were similar (2.2% vs. 1.5%, P = 0.708). Complete false lumen thrombosis was an independent predictor of no growth (hazard ratio [HR]: 3.640, P = 0.011), while a larger sinotubular junction (STJ) (HR: 0.304, P = 0.004) and female gender (HR: 0.325, P = 0.030) were negative predictors of no growth.Conclusions: Complete false lumen thrombosis was a predictor of no growth, while a large STJ and female gender were predictors of aortic growth. This study might help predict which medically treated TBAD patients might show a stable clinical course during follow-up.