Mismatch between self-estimated and objectively assessed exercise capacity in patients with congenital heart disease varies in regard to complexity of cardiac defects.

Aim: Regular evaluation of physical capacity takes a crucial part in long-term follow-up in patients with congenital heart disease (CHD). This study aims to examine the accuracy of self-estimated exercise capacity compared to objective assessments by cardiopulmonary exercise testing in patients with CHD of various complexity.

Methods: We conducted a single centre, cross-sectional study with retrospective analysis on 382 patients aged 8-68 years with various CHD who completed cardiopulmonary exercise tests. Peak oxygen uptake was measured. Additionally, questionnaires covering self-estimation of exercise capacity were completed. Peak oxygen uptake was compared to patient's self-estimated exercise capacity with focus on differences between complex and non-complex defects.

Results: Peak oxygen uptake was 25.5 ± 7.9 ml/minute/kg, corresponding to 75.1 ± 18.8% of age- and sex-specific reference values. Higher values of peak oxygen uptake were seen in patients with higher subjective rating of exercise capacity. However, oxygen uptake in patients rating their exercise capacity as good (mean oxygen uptake 78.5 ± 1.6%) or very good (mean oxygen uptake 84.8 ± 4.8%) was on average still reduced compared to normal. In patients with non-complex cardiac defects, we saw a significant correlation between peak oxygen uptake and self-estimated exercise capacity (spearman-rho -0.30, p < 0.001), whereas in patients with complex cardiac defects, no correlation was found (spearman-rho -0.11, p < 0.255).

Conclusion: The mismatch between self-estimated and objectively assessed exercise capacity is most prominent in patients with complex CHD.Registration number at Charité Universitätsmedizin Berlin Ethics Committee: EA2/106/14.