Predictors of exercise capacity in patients with atrial correction of transposition of great arteries

OBJECTIVES: To examine the relationship of clinical, biochemical and imaging parameters to maximum oxygen uptake in patients after atrial correction of transposition of great arteries. BACKGROUND: Exercise tolerance is a key determinant of quality of life in patients with adult congenital heart disease. It is determined by a large scale of factors often different from general cardiology. METHODS: 86 consecutive patients after Senning correction of TGA were subjected to clinical and echocardiographic examination, Holter monitoring, blood tests of NT-proBNP, MRI of the heart and exercise test. Parameters of these examinations were correlated to VO2 max. RESULTS: The average age of patients was 28±3.5 years. The average systemic right ventricular function determined by MRI was 51.9±7.9 %. The average NT-proBPN was 124.3±23.6 ng/l, VO2 max. 31.7±6.5 ml/kg/min and the heart rate reserve 106±24 /min. Neither systemic right ventricular systolic function nor NT-proBPN predicted VO2 max., whereas the heart rate reserve did (p=0.003). CONCLUSION: An inability to increase heart rate during exercise noted in a considerable number of patients after atrial switch of TGA caused a decreased exercise tolerance. It is not solely the global systolic function of either ventricle that influences the exercise performance, rather it is the ability to increase heart rate and overall cardiac output appropriately (Tab. 3, Fig. 6, Ref. 28).