Two decades after the arterial switch operation: stable right ventricular function but reduced exercise capacity

Area of Science:

• Cardiology
• Pediatric Cardiology
• Congenital Heart Disease

Background:

• Right ventricular (RV) function and exercise capacity are crucial prognostic indicators in patients with transposition of the great arteries (TGA) following arterial switch operation (ASO).
• Longitudinal assessment of RV dimensions, global function, and exercise capacity is essential for understanding long-term outcomes after ASO.
• Comparing outcomes between TGA patients with and without RV pressure overload provides insights into specific risk factors.

Purpose of the Study:

• To longitudinally evaluate right ventricular (RV) dimensions, global function, and exercise capacity in patients with transposition of the great arteries (TGA) after arterial switch operation (ASO).
• To compare the changes in RV parameters and exercise capacity over time between TGA patients with and without RV pressure overload.
• To assess the stability of RV dimensions, function, strain, and aortic root dimensions during long-term follow-up post-ASO.

Main Methods:

• Retrospective analysis of TGA patients post-ASO with two cardiovascular magnetic resonance (CMR) examinations between 2004 and March 2024.
• Measurement of cardiac volumes, function, strain, and vessel dimensions using CMR.
• Categorization of patients based on RV pressure overload and comparison of repeated exercise tests in a subset.

Main Results:

• RV volumes, function, and strain remained stable during long-term follow-up (median 21 years post-ASO).
• Aortic root dimensions showed no significant progression during long-term follow-up.
• Exercise capacity (VO2peak) declined in a significant portion of patients (46% at long-term follow-up), unrelated to peak heart rate or chronotropic index. No differences were observed between patients with and without RV pressure overload.

Conclusions:

• Long-term exercise capacity is impaired in a substantial number of TGA patients post-ASO.
• Right ventricular dimensions, global function, strain, and aortic root dimensions are stable during long-term follow-up after ASO.
• The decline in exercise capacity is a key concern, necessitating continued monitoring and management strategies.