Only slow decline in exercise capacity in the natural history of patients with congenital heart disease: A longitudinal study in 522 patients

Objective: Exercise studies in patients with congenital heart disease (CHD) suggest that exercise capacity declines progressively. This study aims to assess the natural history of exercise capacity in patients with CHD from serial cardiopulmonary exercise tests (CPETs) and to identify factors that are associated with the rate of decrease. Patients and methods: From July 2001-August 2012 we included all patients with CHD who had two CPETs separated by at least six months. Patients with any kind of intervention (surgery, catheter intervention, or change in medication) between the two tests were excluded. Results: In 522 patients (24.8 ± 10.2 years, 215 female) peak oxygen uptake (VO₂) was reduced to 80.0 ± 20.7% predicted and declined significantly during a mean follow-up of 2.5 ± 1.8 years to 78.1 ± 20.4% predicted (p < 0.0001). The annual declining rate of peak VO₂ was only -1.01 ± 6.83% points per year. Higher peak oxygen pulse (% predicted) (r = -0.230; p < 0.0001), higher peak VO₂ (% predicted) (r = -0.213; p < 0.0001) at baseline testing and the presence of a pacemaker (r = -0.095; p = 0.031) were only weakly associated with a more rapid decline in peak VO₂ (% predicted) over time. The decline was independent from diagnosis, heart defect severity, systemic ventricular morphology and age. Conclusions: There was a progressive, but slow, decline in the natural history of exercise capacity in all kind of patients with CHD. Except for having a pacemaker, we could not find any factors associated with this decline.