The 'R sign' as a potential risk factor for progression of uncomplicated Type B aortic dissection: a case series

Complicated and uncomplicated Type B aortic dissection (TBAD) need distinct therapeutic pathways. While TBAD is a complex and dynamic clinical entity, ∼75% of cases present as uncomplicated initially. However, up to half of these may progress to complicated TBAD, highlighting the need for better prognostic tools. In this case series, we report a novel potential radiological risk factor for progression, the 'R sign', to contribute to a deeper understanding of this disease's behaviour.

We present two male patients with TBAD. Both cases exhibited a localized dissection at the top of the aortic arch's greater curvature on computed tomography angiography (CTA), which we term the 'R sign'. Both patients were initially admitted with uncomplicated TBAD. Patient 1: a 46-year-old man was stable on medical therapy until experiencing sudden chest tightness, at which point CTA confirmed progression to Type A dissection. Patient 2: a 54-year-old man, also managed medically for uncomplicated TBAD, suffered a sudden recurrence of back pain, with CTA confirming progression to Type A dissection.

This case series highlights a previously unrecognized subtype of aortic dissection. In both presented cases, this specific form of TBAD progressed to Type A during the acute phase. Early identification of this high-risk uncomplicated TBAD variant is critical for patient prognosis, as it may need urgent intervention as a complicated TBAD. We present this entity to raise awareness and call for further multi-centre studies to validate our observations in larger cohorts.