Declining cardiopulmonary exercise capacity is not associated with worsening systolic systemic ventricular dysfunction in adults with transposition of great arteries after atrial switch operation

Background/Objective: Cardiopulmonary exercise capacity is often reduced in patients with transposition of the great arteries after atrial switch operation. Reduced exercise capacity may be caused by deterioration of systemic right ventricular function over time. This study analyzed serial changes in systemic right ventricular function and cardiopulmonary exercise capacity in young adults with transposition of the great arteries after atrial redirection surgery. Methods: Twenty-one patients (37% female, mean age 23.2 ± 3.3, mean age at surgery 12.8 ± 14 years) with transposition of the great arteries after atrial switch operation were included in this study. Patients were followed up for a mean period of 39.6 ± 13.1 months. Exercise capacity expressed as peak VO₂max, systemic right ventricular function and subpulmonary left ventricular function assessed by cardiac magnetic resonance imaging and NT-proBNP levels were obtained at baseline and follow-up. Changes in peak VO₂max were correlated to changes in cardiac magnetic resonance imaging and NT-proBNP levels. Results: Baseline peak VO₂max decreased significantly (28.31 ± 5.80mL/kg/min vs. 25.17 ± 5.71mL/kg/min, P = .005) on follow-up. Cardiac magnetic resonance imaging parameters of systemic right ventricular ejection fraction as well as subpulmonary left ventricular ejection fraction remained unchanged (44.68 ± 6.59% vs. 45.65 ± 9.60%, P = .54, 60.18 ± 6.29% vs. 61.52 ± 5.30%, P = .35). NT-proBNP levels did not increase (211.7 ± 85.7ng/mL vs. 261.2 ± 182.2ng/mL, P = .16). Conclusions: After atrial switch operation for transposition of the great arteries we observed a declining functional exercise capacity. This was not associated with worsening systemic right ventricular function, suggesting that other factors are contributing to the decline in physical exercise capacity.