Narrow true lumen favors future complication even in small diameter of type B aortic dissection.

Background: Uncomplicated Stanford type B aortic dissection (TBAD) is associated with aortic complications in the subacute or chronic phase, but it is still unclear in which patients these complications occur. The objective of this study was to identify the ideal imaging parameter predictive of the risk of aorta-related complications in patients with uncomplicated TBAD.

Methods: A retrospective study was conducted using prospectively collected data from patients with uncomplicated TBAD at two local hospitals in Japan. Computed tomography (CT) images were analyzed serially, and their association with "aorta-related complication" during follow-up was assessed.

Results: During a mean follow-up of 3.5 years, 53 out of 213 patients with uncomplicated TBAD experienced the aorta-related complications, among which 50 (23.5%) were aortic enlargement. Receiver operating characteristic curve analysis revealed that a low true lumen area ratio (TLAR) (<2.9%) at initial subacute phase was a significant prognostic factor for late aorta-related complications (P<0.001). The Cox regression analysis indicated that low TLAR [hazard ratio (HR), 6.32; 95% confidence interval (CI): 2.72-14.69] and an enlargement of the false lumen area (HR, 6.09: 95% CI: 2.22-16.7) were independent predictors of aorta-related complications. Subanalysis revealed a TLAR of 52.9% or less increased the risk of future aorta-related complications, even when the aortic diameter was smaller than 40 mm (P<0.001).

Conclusions: A narrow true lumen area at early subacute phase and an enlargement of the false lumen area are potentially good predictors to help us to identify a high-risk subgroup of patients who may benefit from earlier and more aggressive therapy. In particular, a narrow true lumen area is an independent risk factor for the future aorta-related complications, even when the aortic diameter is small.