Objective To describe the range of aortic dimensions and severity of aortic valve regurgitation (AR) in patients after the Fontan operation, examine rate of growth over time and identify risk factors for severe aortic dilation.

Methods This was a single-centre retrospective study of Fontan patients who underwent magnetic resonance angiography.

Results Between 2005 and 2014, there were 235 patients (median age 18.8 years). The aortic root (median Z-score 3.2) and ascending aorta (AAo) (median Z-score 4.1) were dilated. Severe aortic root or AAo dilation (Z-score ≥6.0) was present in 8.5% and 22%, respectively. Multivariable analysis identified older age at Fontan (adjusted odds ratio (AOR): 1.1 per year; 95% CI 1.04 to 1.2; p=0.002), male gender (AOR: 16.3; 95% CI 1.8 to 144.9; p=0.01) and higher mean blood pressure (AOR: 1.5 per 10 mm Hg; 95% CI 1.01 to 2.3; p=0.05) as factors associated with severe aortic root dilation. Older age at Fontan (AOR: 1.1 per year; 95% CI 1.02 to 1.1; p=0.01), male gender (AOR: 3.3; 95% CI 1.5 to 7.5; p=0.004) and left ventricular morphology (AOR: 2.6; 95% CI 1.3 to 5.1; p=0.007) were associated with severe AAo dilation. Over a median of 3.3 years, there was no significant increase in aortic dimension. Most patients (96%) had mild or less AR.

Conclusions The Fontan aorta is enlarged at the aortic root and AAo. Older age at Fontan, male gender, elevated blood pressure and left ventricular morphology are associated with severe aortic dilation. Although trivial-mild AR is common, significant regurgitation is infrequent.