Predictive Value of V̇O2peak in Adult Congenital Heart Disease in Comparison With Heart Failure With Reduced Ejection Fraction

Peak oxygen consumption (V̇O_2peak) is used to predict outcomes and time to transplantation in patients with heart failure with reduced ejection fraction (HFrEF); V̇O_2peak also has predictive utility in patients with adult congenital heart disease (ACHD). However, the predictive value of a given V̇O_2peak on cardiac events in patients with ACHD compared to HFrEF, especially after adjustment for age and sex, is unclear. Therefore, we performed a longitudinal cohort study comparing patients with ACHD to patients with HFrEF. The cohorts were sex and age matched (±10 years). V̇O_2peak tests were conducted from 1993 to 2012. Cardiac events included death, cardiac transplantation, and LVAD placement. Events were obtained via electronic medical record, SSDI, and phone interview. Cox proportional-hazard regression analyses were used to evaluate relationships of event-free survival with predictor variables. Patients with ACHD (N = 137) and HFrEF (N = 137) had median follow-up times of 19.0 years (14.8 to 21.1) and 14.5 years (13.4 to 15.6), respectively. In multivariable models, Higher V̇O_2peak was associated with lower risk for a cardiac event, independent of age and sex, in both ACHD (HR 0.89, 95% CI 0.83 to 0.96, p = 0.002) and HFrEF (HR 0.86, 95% CI 0.82 to 0.91, p <0.001). Male sex was associated with greater risk of a cardiac event HFrEF (HR 1.90, 95% CI 1.24 to 2.90, p = 0.003) but not in ACHD group. After multivariable adjustment (Beta-blockers, sex, and V̇O_2peak), having ACHD conferred a 71% lower risk of cardiac events compared to a HFrEF diagnosis (HR 0.29, 95% CI 0.18 to 0.47, p <0.001). V̇O_2peak independently predicts event-free survival among adults with ACHD or HFrEF and has clinical utility in outpatient settings. Patients with ACHD have a better prognosis after multivariable adjustment including V̇O_2peak compared to HFrEF.