Exercise Testing Identifies Patients at Increased Risk for Morbidity and Mortality Following Fontan Surgery

Objective. The objective of this study was to examine the relationship between exercise test data and mortality in patients who have had the Fontan procedure. Design. The study was designed as a retrospective cohort study. Setting. The study was set in a tertiary care center. Patients. All study participants were Fontan patients >= 16 years old who had cardiopulmonary exercise tests at our institution between November 2002 and March 2010. The first exercise test with adequate effort during the study period was retained for analysis. We enrolled 146 patients at a median age of 21.5 years (16.0-51.6); 15.8 years (1.2-29.9) after Fontan surgery. Outcome Measures. The outcome measures were exercise test data (peak oxygen consumption, peak heart rate, etc.); mortality. Results. Peak oxygen consumption averaged 21.2 +/- 6.2 mL/kg/min, 57.1 +/- 14.1% predicted. Follow-up data were collected 4.0 +/- 2.0 years (range 0.3-7.7) after the exercise test. Sixteen patients (11%) died during follow-up; their peak oxygen consumption (16.3 +/- 4.0 mL/kg/min) was significantly less than the survivors' (21.8 +/- 6.2 mL/kg/min; P < .0001). Recursive partitioning and Cox proportional hazards modeling revealed that the hazard for death for patients with a peak oxygen consumption of <16.6 mL/kg/min was 7.5 (95% confidence interval: 2.6, 21.6; P < .0002) times that of patients with a higher peak oxygen consumption. Similarly, the hazard ratio for patients with peak-exercise heart rates of <122.5 bpm was 10.6 (3.0, 37.1; 0 < 0.0002). Data from exercise tests could also identify patients at increased risk for a combined morbidity/mortality end point. Conclusions. In adults with Fontan surgery, exercise test data can identify patients at increased risk of midterm morbidity and mortality.