Prognostic Value of Exercise Variables in 335 Patients after the Fontan Operation: A 23-year Single-center Experience of Cardiopulmonary Exercise Testing

BACKGROUND: The prognostic value of cardiopulmonary exercise testing (CPX) for mortality risk remains controversial in Fontan patients. PURPOSE: Our goal of the present study was to clarify the prognostic value of major CPX variables and the factors determining exercise capacity in a large cohort of Fontan patients. METHODS: Since 1990, heart rate (HR), oxygen uptake (VO2 ), and ventilatory equivalent for carbon dioxide production (VE/VCO2 ) at peak exercise were determined in 335 Fontan patients (18 ± 5 years old), and the CPX variables were compared with the clinical profile and events. RESULTS: When compared with 209 controls, peak HR (148 ± 24 bpm), VO2 (27 ± 7 mL/kg/minute, 61 ± 15%), and VE/VCO2 (40 ± 8 117 ± 24%) were markedly impaired in the Fontan patients (P < .0001). During a follow-up of 3.1 ± 2.7 years, 62 Fontan pathophysiological-associated events requiring unscheduled hospitalization (USH) occurred, and 24 patients died. All the CPX variables predicted the USH and mortality (P < .001-.0001). On multivariate analysis, in addition to use of diuretics (P = .0007) and low cardiac index (P = .0426), peak VO2 independently predicted the USH (hazard ratio: 0.95 per %, 95% confidence interval: 0.91-0.99, P = .014), while for mortality, multivariate analysis revealed that, in addition to heterotaxy syndrome (P = .0128) and year at first Fontan operation (P = .0532), peak VO2 independently predicted mortality (hazard ratio: 0.88 per %, 95% confidence interval: 0.76-0.98, P = .0217). CONCLUSION: Fontan patients exhibit markedly impaired CPX variables, and all the major variables, especially peak VO2 , predicted the risk of both morbidity and mortality.