Advanced Imaging to Phenotype Patients With a Systemic Right Ventricle

Area of Science:

• Cardiology
• Congenital Heart Disease
• Cardiovascular Imaging

Background:

• Adults with complete transposition of the great arteries (TGA) after atrial switch (TGA-Mustard/Senning) and congenitally corrected TGA (cc TGA) often experience reduced ventricular function and exercise capacity.
• Advanced imaging and exercise testing are crucial for phenotyping these complex patients.

Purpose of the Study:

• To compare the cardiac structure, function, and exercise response in adults with TGA-Mustard/Senning versus cc TGA using advanced imaging and cardiopulmonary exercise testing.
• To identify distinct characteristics and exercise limitations in these two TGA subtypes.

Main Methods:

• Echocardiography, cardiopulmonary exercise testing, and cardiovascular magnetic resonance imaging (CMR) were performed on 33 adults with a systemic right ventricle (TGA-Mustard/Senning or cc TGA) and 12 healthy controls.
• CMR included rest and exercise assessments during a 4-stage bicycle test.

Main Results:

• TGA-Mustard/Senning patients exhibited greater global circumferential strain but a fall in end-diastolic and stroke volumes during exercise, unlike cc TGA and controls.
• Septal extracellular volume (ECV) was higher in cc TGA compared to TGA-Mustard/Senning.
• Despite differences, cardiac index and peak oxygen uptake were similar between TGA groups due to greater heart rate reserve in TGA-Mustard/Senning.

Conclusions:

• Significant differences in myocardial contraction patterns, septal ECV, and exercise response exist between TGA-Mustard/Senning and cc TGA.
• Pooled analyses of systemic right ventricle patients should be approached cautiously due to these distinct characteristics.
• Longitudinal studies are needed to determine if abnormal exercise response predicts future heart failure.