LONGITUDINAL EXERCISE FUNCTION OF PATIENTS WITH REPAIRED TETRALOGY OF FALLOT

Patients with repaired tetralogy of Fallot have a reduced percentage of predicted peak oxygen consumption (VO2) and percentage of oxygen pulse (O2P%) compared to healthy controls. Because data regarding the progression of exercise intolerance in these patients is limited, we sought to analyze the serial exercise data from patients with Tetralogy of Fallot to quantify the changes in their exercise capacity over time and to identify associations with clinical and cardiac magnetic resonance imaging variables. The data from cardiopulmonary exercise tests (CPXs) from 2002 to 2010 for patients with repaired tetralogy of Fallot with >2 CPXs separated by >12 months were analyzed. Tests occurring after interventional catheterization or surgery were excluded. A total of 70 patients had 179 CPXs. They had a median age at the initial study of 23.6 years and an interval between the first and last CPX of 2.8 years. At the initial CPX, the peak VO2 was 27.6 8.8 ml/kg/min (78 19% of predicted), and the peak O2P% was 89 22% of predicted. At the most recent study, the peak VO2 averaged 25.0 7.4 ml/kg/min (73 16% of predicted), and the peak O2P% averaged 83 20% (p <0.01) for each versus the initial CPX. The decrease in the peak VO2 was strongly associated with a decrease in O2P% and an increase (worsening) in the slope of the minute ventilation-versus-carbon dioxide production relation. Changes in the peak VO2 did not correlate with concomitant changes in any other CPX variable. The rate of decrease was not related to a history of shunt palliation, age at CPX, or any other baseline clinical parameter, including cardiac magnetic resonance measurements. In conclusion, the exercise capacity of patients with repaired tetralogy of Fallot tends to decrease over time. This deterioration is variable and unpredictable and is primarily related to a decrease in the forward stroke volume at peak exercise. © 2011 Elsevier Inc. All rights reserved. (Am J Cardiol 2011;108:99‐105) Currently, information regarding the change in the exercise capacity over time in patients with congenital heart disease in general, and those with repaired tetralogy of Fallot (rTOF) in particular, is limited. In this population, several cross-sectional studies have reported an average peak oxygen consumption (VO2) of 51% to 95% predicted. 1– 8 Given the greatly increased hemodynamic demands imposed on the right ventricle during exercise, the low peak VO2 of these patients with residual right-sided heart disease is not surprising. The potential factors responsible for the depressed exercise capacity of patients with rTOF are numerous; past studies have implicated residual pulmonary regurgitation, pulmonary artery distortion, impaired lung function, chronotropic impairment, and ventricular dysfunction. 4,5,9 –16 However, a study of the natural history of the exercise function of patients with rTOF, according to assessments using modern cardiopulmonary exercise testing (CPX) technology, has not been undertaken. The purpose of the present study was to analyze the serial CPX data from patients with rTOF to quantify the changes in their exercise capacity over time. We also sought to identify the clinical and cardiac magnetic resonance imaging variables 16 associated with any observed changes in exercise function.