Improved Exercise Tolerance after Enzyme Replacement Therapy in Pompe's Disease

PURPOSE: Enzyme replacement therapy (ERT) has recently became available for Pompe's disease. Data on the effects of ERT on physiological variables related to exercise tolerance have never been published. METHODS: Pulmonary gas exchange, cardiac output (by impedance cardiography), vastus lateralis muscle O2 extraction (by near-infrared spectroscopy) were determined during cycle ergometer exercise in a 50-year-old patient BEFORE and after 1, 12 and 24 months of ERT. RESULTS: At the same constant-workload submaximal exercise, rates of self-perceived exertion and values of respiratory exchange ratio, pulmonary ventilation and heart rate were lower during ERT vs.. BEFORE, suggesting an increased exercise tolerance. Peak oxygen uptake (VÙO2peak) increased by ~35% from BEFORE (0.64 L/min, or 11.4 ml/kg/min) to 1 month (0.88 L/min, or 15.7 ml/kg/min) of treatment, and did not significantly change thereafter. Also peak cardiac output significantly increased during ERT, whereas peak skeletal muscle fractional O2 extraction was unchanged compared to BEFORE. CONCLUSIONS: Improvements of peak exercise capacity and exercise tolerance at submaximal workloads were observed in a patient with Pompe's disease after 1 month of ERT, with no further changes during the ensuing treatment period (up to 24 months).