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Objective:
Spontaneous coronary artery dissection (SCAD) is recognized as an important differential diagnosis in low-risk patients with chest pain, particularly among young women. SCAD is routinely associated with extracoronary vascular abnormalities, most commonly fibromuscular dysplasia, but also less commonly connective tissue disorders and aortopathy syndromes. Vascular abnormalities that merit follow-up affect large vessels such as thoracic aorta dilatation. However, the prevalence of thoracic aortic dilatation and its association with SCAD is unknown. Coronary computed tomography angiography (CTA) is an ideal noninvasive imaging modality to evaluate for SCAD and concurrent thoracic aorta dilatation that merits further diagnostic workup and more frequent monitoring. Thus, the objectives of this exhibit are to compare thoracic aortic dimensions and the prevalence of thoracic aortic dilatation in patients with and without SCAD on coronary CTA.

Materials and Methods:
We performed a retrospective 1:1 case-control study of 158 patients with SCAD on coronary CTA versus 158 non-SCAD controls at a tertiary hospital from June 2016 through December 2021. Maximum aortic diameters (mm) were measured at the level of the sinus of Valsalva, sinotubular junction, ascending aorta, and descending aorta, and were divided by body surface area (BSA; 2m ) to calculate BSA-indexed maximum diameters (mm/m^2). Thoracic aortic dilatation was defined as sinus of Valsalva, sinotubular junction, or ascending aorta =>40 mm. We compared aortic diameters and prevalence of aortic dilatation between the groups and measured the associations of aortic diameters with SCAD, adjusting for clinical covariates using logistic regressions.

Results:
Among 316 adults (mean age 49.9 ± 11.9 years, 79.7% women), patients with SCAD had larger BSA-indexed maximum diameters at all aortic levels with the largest difference at the ascending aorta (2.8 mm/m^2, p < 0.001). Overall, thoracic aorta dilatation at any level was more common in patients with SCAD vs. controls (9% v 0%, p<0.001), observed more frequently in males vs. females (28% versus 4%, p < 0.001). BSA-indexed aortic diameters were independently associated with SCAD at all thoracic aortic landmarks (range: OR 1.19–1.64 [95% CI 1.08 - .95], p< 0.001), adjusting for clinical factors associated with SCAD in univariable analysis (age, sex, ethnicity, and hyperlipidemia).

Conclusion:
Besides being a reliable method to detect SCAD, coronary CTA provides valuable information on aortic diameters. Patients with SCAD, males in particular, present with a higher prevalence of enlarged aortas than matched non-SCAD controls. This observation may aid in the detection of SCAD on coronary CTA and suggest a common underlying pathophysiological pathway. Thoracic aortic dilatation in SCAD may warrant further evaluation for underlying vasculopathy, preventative clinical management, and additional imaging surveillance.