Exercise intolerance in adult congenital heart disease: Comparative severity, correlates, and prognostic implication

Background-Although some patients with adult congenital heart disease (ACHD) report limitations in exercise capacity, we hypothesized that depressed exercise capacity may be more widespread than superficially evident during clinical consultation and could be a means of assessing risk. Methods and Results-Cardiopulmonary exercise testing was performed in 335 consecutive ACHD patients (age, 33±13 years), 40 non-congenital heart failure patients (age, 58± 15 years), and 11 young (age, 29±5 years) and 12 older (age, 59±9 years) healthy subjects. Peak oxygen consumption (peak V̇O₂) was reduced in ACHD patients compared with healthy subjects of similar age (21.7±8.5 versus 45.1±8.6; P<0.001). No significant difference in peak V̇O₂ was found between ACHD and heart failure patients of corresponding NYHA class (P=NS for each NYHA class). Within ACHD subgroups, peak V̇O₂ gradually declined from aortic coarctation (28.7±10.4) to Eisenmenger (11.5±3.6) patients (P<0.001). Multivariable correlates of peak V̇O₂ were peak heart rate (r=0.33), forced expiratory volume (r=0.33), pulmonary hypertension (r=-0.26), gender (r=-0.23), and body mass index (r=-0.19). After a median follow-up of 10 months, 62 patients (18.5%) were hospitalized or had died. On multivariable Cox analysis, peak V̇O₂ predicted hospitalization or death (hazard ratio, 0.937; P=0.01) and was related to the frequency and duration of hospitalization (P=0.01 for each). Conclusions-Exercise capacity is depressed in ACHD patients (even in allegedly asymptomatic patients) on a par with chronic heart failure subjects. Lack of heart rate response to exercise, pulmonary arterial hypertension, and impaired pulmonary function are important correlates of exercise capacity, as is underlying cardiac anatomy. Poor exercise capacity identifies ACHD patients at risk for hospitalization or death.