Cardiopulmonary exercise test in adults with prior Fontan operation: The prognostic value of serial testing

Background The purpose of the study was to determine the role of cardiopulmonary exercise test (CPET) indices in predicting cardiovascular adverse events (CAEs) in patients with Fontan palliation. CAE was defined as death or cardiac surgery. Methods Retrospective review of adult Fontan patients who had treadmill CPET at Mayo Clinic, 1994–2013. Patients with loss of follow-up defined as ≥ 2 years without clinical follow-up were excluded. The results of serial CPETs were reviewed, and patients with CPETs meeting the following criteria were selected for analysis: maximum effort on serial CPETs, minimum of 3-year interval between CPETs, and absence of CAE between CPETs. Results A total of 145 patients met inclusion criteria for the study; age at baseline CPET was 24 ± 3 years; age at Fontan operation was 11 ± 5 years; and 91 (63%) were males. Baseline peak oxygen consumption (VO₂) was 22.7 ± 5.4 ml/kg/min (63 ± 11% predicted), peak heart rate was 135 ± 31 beats per minute, and oxygen saturation at peak exercise was 86 ± 7%. Serial CPETs were performed in 71/145 patients (49%); mean duration between CPETs was 3.8 ± 0.3 years. The % predicted peak VO₂ decreased by 1.7 ± 0.9 percentage points/year. CAE (deaths n = 22; cardiac surgery n = 45) occurred in 54/145 patients (37%) within 8 ± 3 years. Decline in % predicted peak VO₂ ≥ 3 percentage points/year was the only predictor of 5-year risk of CAE (HR 1.86, 95% CI 1.11–3.48, P = 0.02). Conclusions Serial CPET is prognostic of CAE in the adult Fontan population, and can be used to risk stratify these patients.