Aortic arch shape after arch repair predicts exercise capacity: a multicenter analysis

Coarctation of the aorta is associated with long term morbidity including decreased exercise capacity, despite successful repair. In the absence of discrete recoarctation, the hemodynamic mechanism remains unknown. This multicenter study evaluated the relationship between aorta shape, flow, and exercise capacity in patients after arch repair, specifically through the lens of aortic size mismatch and descending aortic (DAo) flow and their association with exercise. Cardiac magnetic resonance (CMR), cardiopulmonary exercise test, and echocardiogram data within 1 year were analyzed from 58 patients (age 28 ± 10 years, 48% male) across 4 centers with history of isolated arch repair. Aortic arch measurements were correlated with % predicted VO2max with sub-group analyses of those with residual arch obstruction, bicuspid aortic valve, and hypertension. Ascending aorta (AAo) to DAo diameter ratio (DAAo/DDAo) was negatively correlated with % predicted VO2max. %DAo flow positively correlated with VO2max. Sub-analyses demonstrated the negative correlation of DAAo/DDAo with VO2max was maintained only in patients without arch obstruction and with a bicuspid aortic valve. Smaller aortic arch measurements were associated with both hypertension and exercise-induced hypertension. Aorta size mismatch, due to AAo dilation or small DAo, and associated decreased %DAo flow, correlated significantly with decreased exercise capacity after aortic arch repair. These correlations were stronger in patients without arch obstruction and with a bicuspid aortic valve. Aorta size mismatch and %DAo flow capture multiple mechanisms of altered hemodynamics beyond blood pressure gradient or discrete obstruction and can inform the definition of a successful repair.