Fabry disease is a rare genetic disease caused by mutations in a gene encoding for the enzyme alpha-galactosidase A. This results in the accumulation of a type of fat called globotriaosylceramide (Gb3 or GL-3) in the body, which the enzyme would normally break down, especially in the heart, kidneys, skin, brain, and lungs.

Impaired exercise capacity

Impaired exercise capacity is a common experience for people with Fabry disease. Patients usually become tired even with mild activity. Moreover, physical exercise and activity can trigger pain episodes.

Adult patients show decreased lung function and heart problems that progressively worsen with age, including enlarged heart, irregular heartbeats, malfunctioning heart valves, heart attack, and heart failure. Therefore, people with Fabry disease have to modify their physical activities and exercise routine, or avoid exercise altogether.

Studies on exercise and Fabry disease

A study published in the American Journal of Medical Genetics used cardiopulmonary exercise testing (CPET) to evaluate the aerobic fitness (ability to use oxygen as an energy source), cardiac function, and heart response to physical activity in Fabry disease patients. The study included 29 patients and age-matched healthy volunteers. All participants were subjected to two CPET protocols. In the first one, 18 patients and 18 healthy volunteers were subjected to the Bruce protocol involving a treadmill exercise, and in the second, 11 patients and 11 healthy volunteers underwent the ramp protocol involving bike exercises.

Results showed that Fabry disease patients had significantly lower heart rates at peak exercise (151.2 vs. 178.6 in healthy participants), maximal oxygen consumption (23.7 vs. 33.9), and peak oxygen pulse (volume of blood pumped by the heart: 12.1 vs. 15.2), compared with healthy controls. The study also showed a possible link between heart disease and exercise performance in Fabry disease patients using results of cardiac magnetic resonance imaging — an imaging method that evaluates structural details within and around the heart. The maximal oxygen consumption was directly linked to the volume of blood in the right heart ventricle after relaxation, called diastole, and after a contraction, called systole.

Another study published in the Journal of Inherited Metabolic Disease investigated the impact of enzyme replacement therapy (ERT) on exercise tolerance. In this study, 15 patients with Fabry disease underwent baseline cardiopulmonary exercise tests, with six of them being randomized in a 2:1 ratio to receive ERT or a placebo. The tests were recorded for all patients at baseline and then every three months for at least 18 months. The baseline test was compared to the last two exercise tests for each patient.

The results showed that the mean maximal oxygen consumption for those receiving ERT increased by 0.459 ± 0.64 L per minute from a basal value of 1.680 ± 0.67 L per minute, whereas it decreased in patients in the placebo group by 0.116 ± 0.44 L per minute from the basal value of 1.462 ± 0.25 L per minute. Furthermore, the mean oxygen pulse, which is the mean oxygen consumption divided by heart rate, increased 1.71 fold in ERT-treated patients compared to 0.025 in patients taking the placebo. These results demonstrated that exercise tolerance improved significantly in patients receiving ERT and that cardiopulmonary exercise testing is useful for measuring the response to therapy in Fabry disease patients.

 

Last updated: Feb. 18, 2020

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