Anatomical/Physiological Correlates of Functional Capacity in Adults With Repaired and Nonsevere Coarctation of the Aorta.

Background: There is limited data regarding the interplay of anatomic and physiologic parameters with exercise capacity in adults with native or recurrent nonsevere coarctation of the aorta (CoA).

Objectives: The objective of this study was to use exercise stress echocardiography and cardiac magnetic resonance imaging to identify anatomic and physiologic correlates of exercise capacity in these patients.

Methods: We conducted a single-center retrospective analysis of 54 adults with nonsevere CoA (repaired or unrepaired) followed at our institution between 2015 and 2020. Resting coarctation gradients were obtained using echocardiography. Exercise gradients and functional capacity were assessed using exercise stress echocardiography. Aorta anatomy was obtained using magnetic resonance imaging.

Results: Coarctation-to-diaphragm ratio correlated with minutes of exercise (r = 0.56,  < 0.01) and metabolic equivalents (r = 0.49,  < 0.01). These relationships remained significant after controlling for use of beta-blockers, valvular disease, and type of coarctation repair. Minutes of exercise correlated with mean resting gradients (r = -0.39,  < 0.05). Coarctation-to-diaphragm ratio correlated with peak and mean resting gradients (r = -0.34,  < 0.05; r = -0.48,  < 0.01). Patients with coarctation-to-diaphragm ratio ≤0.7 achieved fewer metabolic equivalents (11.1 ± 1.9 vs 12.8 ± 2.2,  < 0.05) and minutes of exercise (10.3 ± 2.0 vs 12.6 ± 2.7,  < 0.05).

Conclusions: In patients with nonsevere native or recurrent CoA, reduced exercise capacity is correlated with coarctation severity by anatomic size and gradients. Those with a coarctation-to-diaphragm ratio ≤0.7 may represent a subset of patients with nonsevere CoA whose clinical symptoms are only elicited with exercise stress testing. Exercise stress testing and cross-sectional imaging may help identify those who could be considered for earlier coarctation intervention.