Exercise Function of Children with Congenital Aortic Stenosis Following Aortic Valvuloplasty during Early Infancy

OBJECTIVES: The objectives of this study were to characterize the exercise function of patients treated with balloon aortic valvuloplasty at <or=6 months of age, and identify factors associated with exercise dysfunction. BACKGROUND: Balloon aortic valvuloplasty is the primary therapy for neonatal aortic stenosis (AS). Residual and/or acquired abnormalities of left heart structure and function may adversely affect exercise capacity. Methods. We prospectively recruited patients >6 years old with a history of neonatal AS to undergo exercise testing. RESULTS: We enrolled 30 patients (median age 13.1 years) who underwent balloon aortic valvuloplasty at a median age of 12 days. At time of exercise testing, the median maximum Doppler AS gradient was 34 mm Hg (0-70 mm Hg); 11 patients had moderate or severe aortic regurgitation. All patients were asymptomatic. Overall, peak oxygen consumption (VO(2)) was below normal (87 +/- 18% predicted; P < .001), and was severely depressed (<or=70% predicted) in 7 patients (23%). Although peak O(2) pulse was well preserved overall (97 +/- 22% predicted; P= .36), 11 patients had an O(2) pulse <85% predicted, including all patients with VO(2)<or= 70% predicted. Peak heart rate was below normal overall (91 +/- 7% predicted, P < .001), but severe chronotropic dysfunction (<or=70% predicted) was rare (n = 1). Age at testing correlated inversely with peak VO(2) (R(2)= 0.30; P= .002). No other demographic, historical, or echocardiographic variables were associated with peak VO(2). CONCLUSION: Although exercise function is preserved in most patients with a history of AS treated in early infancy, a subset have markedly reduced peak VO(2), usually because of inability to increase stroke volume.