Aims: The New York Heart Association functional classification (NYHA class) is often used to describe the functional capacity of adults with congenital heart disease (ACHD), albeit with limited evidence on its validity in this heterogeneous population. We aimed to validate the NYHA functional classification in ACHD by examining its relation to objective measures of limitation using cardiopulmonary exercise testing (CPET) and mortality.
Methods and results: This study included all ACHD patients who underwent a CPET between 2005 and 2015 at the Royal Brompton, in whom functional capacity was graded according to the NYHA classification. Congenital heart diagnoses were classified according to the Bethesda score. Time to all-cause mortality from CPET was recorded in all 2781 ACHD patients (mean age 33.8 ± 14.2 years) enrolled in the study. There was a strong relation between NYHA class and peak oxygen consumption (peak VO2), ventilation per unit in carbon dioxide production (VE/VCO2) slope and the Bethesda classification (P < 0.0001). Although a large number of 'asymptomatic' (NYHA class 1) patients did not achieve a 'normal' peak VO2, the NYHA class was a strong predictor of mortality, with an 8.7-fold increased mortality risk in class 3 compared with class 1 (hazard ratio 8.68, 95% confidence interval: 5.26-14.35, P < 0.0001).
Conclusion: Despite underestimating the degree of limitation in some ACHD patients, NYHA classification remains a valuable clinical tool. It correlates with objective measures of exercise and the severity of underlying cardiac disease, as well as mid- to long-term mortality and should, thus, be into incorporated the routine assessment and risk stratification of these patients.
Keywords: Cardiopulmonary exercise test; Congenital heart diseases; Mortality; NYHA; Prognosis.
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