Improved Exercise Tolerance after Enzyme Replacement Therapy in Pompe Disease

Abstract

Enzyme replacement therapy (ERT) has recently became available for Pompe disease. Data on the effects of ERT on physiological variables related to exercise tolerance have never been published. Pulmonary gas exchange, cardiac output (by impedance cardiography), and vastus lateralis muscle O₂ extraction (by near-infrared spectroscopy) were determined during cycle ergometer exercise in a 50-yr-old patient before and after 1, 12, and 24 months of ERT. At the same constant-workload submaximal exercise, RPE, R, pulmonary ventilation, and HR were lower during ERT versus before, suggesting an increased exercise tolerance. Peak oxygen uptake (V˙O2peak) increased by ~35% from before (0.64 L·min⁻¹ or 11.4 mL·kg·min⁻¹) to 1 month (0.88 L·min⁻¹ or 15.7 mL·kg·min⁻¹) 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 with before. Improvements of peak exercise capacity and exercise tolerance at submaximal workloads were observed in a patient with Pompe disease after 1 month of ERT, with no further changes during the ensuing treatment period (up to 24 months).