Progressive aortic dilation and aortic stiffness in children with repaired tetralogy of Fallot

Progressive aortic dilation occurs in patients with tetralogy of Fallot (TOF), possibly due to abnormal histopathology of the aortic media that weakens the aortic wall. This medial histopathology may be reflected as aortic stiffness, which in turn may predict progressive aortic dilation. To test this theory, we studied the relationship between aortic wall stiffness, measured by pulse wave velocity (PWV), and subsequent aortic dilation in 32 consecutive patients with repaired TOF. The ascending aortic diameter (AOD) was obtained by two-dimensional transthoracic echocardiography performed at baseline and at the follow-up examination, 7.6 ± 2.0 years after baseline. TOF patients exhibited significantly greater AODs than normal reference values, at baseline (19.8 ± 5.0 vs 14.3 ± 3.1 mm; P = 0.0001) and at the follow-up examination (25.9 ± 3.8 vs 18.1 ± 2.4 mm; P = 0.0001). The observed change in AOD during the follow-up period (0.83 ± 0.43 mm/year) was significantly larger than the change that would be expected by the patient’s growth (0.50 ± 0.25 mm/year; P = 0.0001). The PWV at baseline correlated positively with both AOD at follow-up (P = 0.0018) and the annual rate of aortic dilation (P = 0.0007). On multivariate regression analysis, PWV remained a significant and independent predictor of subsequent aortic dilation. These results suggest a causative role for aortic stiffening in the progressive aortic dilation noted in TOF, indicating that incorporating aortic stiffness as well as aortic diameter in the assessment of TOF aortopathy may help better define the need for, and the timing of, medical intervention.