Background: Patients with Marfan syndrome (MFS) have a highly variable occurrence of aortic complications. Aortic tortuosity is often present in MFS and may help to identify patients at risk for aortic complications.

Methods: 3D-visualization of the total aorta by MR imaging was performed in 211 adult MFS patients (28% with prior aortic root replacement) and 20 controls. A method to assess aortic tortuosity (aortic tortuosity index: ATI) was developed and reproducibility was tested. The relation between ATI and age, and body size and aortic dimensions at baseline was investigated. Relations between ATI at baseline and the occurrence of a clinical endpoint (aortic dissection, and/or aortic surgery) and aortic dilatation rate during 3 years of follow-upwere investigated.

Results: ATI intra-and interobserver agreements were excellent (ICC: 0.968 and 0.955, respectively). Mean ATI was higher in 28 age-matched MFS patients than in the controls (1.92 +/- 0.2 vs. 1.82 +/- 0.1, p = 0.048). In the total MFS cohort, mean ATI was 1.87 +/- 0.20, and correlated with age (r=0.281, p <0.001), aortic root diameter (r=0.223, p=0.006), and aortic volume expansion rate (r=0.177, p=0.026). After 49.3 +/- 8.8 months followup, 33 patients met the combined clinical endpoint (7 dissections) with a significantly higher ATI at baseline than patients without endpoint (1.98 +/- 0.2 vs. 1.86 +/- 0.2, p = 0.002). Patients with an ATI > 1.95 had a 12.8 times higher probability of meeting the combined endpoint (log rank-test, p <0.001) and a 12.1 times higher probability of developing an aortic dissection (log rank-test, p = 0.003) compared to patients with an ATI <1.95.

Conclusions: Increased ATI is associated with a more severe aortic phenotype in MFS patients. (C) 2015 Elsevier Ireland Ltd. All rights reserved.