Aortic rotational flow patterns and stiffness by 4D flow CMR in patients with Loeys-Dietz syndrome compared to healthy volunteers and patients with Marfan syndrome

Abstract

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): La Marató de TV3, Instituto de Salud Carlos III through the project and Spanish Ministry of Science, Innovation and Universities. BACKGROUND Loeys-Dietz (LDS) and Marfan (MFS) syndromes are rare genetic connective tissue disorders associated with progressive aortic dilation, however, aortic dissections have been observed at lower aortic root diameters in LDS than in MFS. Recent CMR studies in MFS patients reported increased aortic stiffness (1–3) and altered rotational flow (4), but research on aortic flow dynamics and biomechanics in LDS is lacking. PURPOSE The aim of this study was to assess rotational aortic flow and aortic stiffness in LDS compared to healthy volunteers (HV) and MFS patients, using 4Dflow CMR. METHODS Twenty-one LDS and 44 MFS patients, without previous aortic dissection or surgery, and 43 HV underwent a non-contrast-enhanced 4D flow CMR. Aortic stiffness was quantified at the AAo and DAo using pulse wave velocity (PWV). In-plane rotational flow (IRF), systolic flow reversal ratio (SFRR) (5) and local aortic diameters were obtained at 20 equidistant planes from the ascending (AAo) to the proximal descending aorta (DAo). RESULTS LDS patients had lower IRF at the distal AAo and proximal DAo compared to HV (p = 0.053 and 0.004, respectively), once adjusted for age, stroke volume and local aortic diameter; but no differences were found with respect to MFS (Figure). Although SFRR at the proximal DAo was increased in LDS patients compared to both HV (p = 0.037) and MFS populations (p = 0.015), once adjusted for age and aortic diameter, the difference in magnitude was small (Figure). On the other hand, AAo and DAo PWV revealed stiffer aortas in LDS patients compared to HV but no differences versus MFS patients (Table). CONCLUSIONS Patients with Loeys-Dietz syndrome showed decreased in-plane rotational flow and abnormally-high regional aortic stiffness compared to healthy controls, and similar hemodynamics and aortic stiffness with respect to patients with Marfan syndrome.