Exercise performance in fontan patients – a single-center Bulgarian study

Aim : Exercise capacity in Fontan patients is reduced compared to healthy peers and progressive decline in cardiovascular function is expected over time. The purpose of this study is to present, analyze and discuss the initial Bulgarian experience with exercise performance of Fontan patients and to compare them to age-matched healthy peers. Additionally, we focused on understanding whether peak oxygen consumption can be predicted based on multiple independent variables. Materials and methods : The research is a retrospective observational study of 11 patients aged 8y-18y, who had undergone the Fontan procedure and underwent cardiopulmonary exercise testing in National Heart Hospital in Sofia, Bulgaria. Data were collected for a 1-year period. Simultaneously, 11 age-matched healthy patients were selected for comparison. Results : Patients with Fontan palliation had lower peak oxygen consumption (23.1 ml/kg/min vs. 30.1 ml/kg/min, P=0.046), percent-predicted peak oxygen consumption (52% vs. 76%, P<0. 001), percent-predicted peak work (56% vs. 82%, P<0.001), percent-predicted peak oxygen consumption at ventilatory anaerobic threshold (37% vs. 48%, P=0.04), resting saturation (93% vs. 97%, P<0.001) and saturation at peak work (84% vs. 95%, P<0.001). Male subjects and patients with left ventricular dominance exhibited a greater peak oxygen consumption. Conclusion : Exercise capacity in the Bulgarian Fontan cohort is reduced relative to healthy controls. Male gender and subjects with left ventricular dominance have a greater peak oxygen consumption.