Abstract 5708: Utility of Exercise Testing to Predict Morbidity and Mortality in Adults with Fontan Surgery
Adults with Fontan surgery are at increased risk for late morbidity and mortality. Although exercise intolerance has been associated with decreased quality of life and functional capacity, its value in predicting late morbidity and mortality remains unknown. To determine if reduced peak oxygen consumption (VO2) is predictive of morbidity (i.e., congestive heart failure (CHF), thrombosis, protein losing enteropathy) and death. We performed a retrospective cohort study of patients ≥16 yrs old s/p Fontan surgery who had an exercise test between 11/1/2002 and 12/31/2007. The first exercise test during the study period was retained for analysis. A total of 112 patients, 50% females, median age 21.5 (16.1–51.1) yrs were enrolled. Fontan type was: lateral tunnel 62; right atrium to pulmonary artery 37; right atrium to right ventricle 6; extra-cardiac conduit 4; other 3. A morphologic left ventricle was present in 74/112 (66%) patients. Patients were followed for 18.9 (3.9 – 31.4) yrs after Fontan surgery and 3.2 (0.2–5.5) yrs after the initial exercise test. Mean peak VO2 was 20.8 ±6.2, ml/kg/min, predicted peak VO2 was 57 ±15%. Most (75/112; 67%) patients had no morbidity end-point at the time of exercise testing; 11 of these went on to develop at least one morbidity end-point (thrombosis 4, CHF 9) at a median follow up time of 1.7 (0.5– 4.0) yrs. Peak VO2 did not predict the onset of morbidity. Mortality occurred in 5/112 patients. Peak VO2 was significantly lower in patients who died during the follow-up. Peak VO2< 15 ml/kg/min carried a relative risk (RR) of 17.7 (95% CI: 2.0 –158.1; p=0.01), and peak VO2 <40 %predicted carried a RR of 6.0 (95% CI: 1.0 –36.02; p=0.05). Exercise intolerance does not predict the onset of CHF, thrombosis, or protein-losing enteropathy. However, it is predictive of all-cause death. Fontan patients with peak VO2 <15 ml/kg/min or 40% predicted are at particularly increased risk for mortality.