Cardiac comorbidities in McArdle disease: case report and systematic review

Myophosphorylase deficiency, also known as McArdle disease or Glycogen Storage Disease type V (GSD-V), is an autosomal recessive metabolic myopathy that results in impaired glycogen breakdown in skeletal muscle. Despite being labelled as a "pure myopathy," cardiac involvement has been reported in some cases, including various cardiac abnormalities such as electrocardiographic changes, coronary artery disease, and cardiomyopathy. Here, we present a unique case of a 72-year-old man with GSD-V and both mitral valvulopathy and coronary artery disease, prompting a systematic review to explore the existing literature on cardiac comorbidities in McArdle disease.

Our systematic literature revision identified 7 case reports and 1 retrospective cohort study. The case reports described 7 GSD-V patients, averaging 54.3 years in age, mostly male (85.7%). Coronary artery disease was noted in 57.1% of cases, hypertrophic cardiomyopathy in 28.5%, severe aortic stenosis in 14.3%, and genetic dilated cardiomyopathy in one. In the retrospective cohort study, five out of 14 subjects (36%) had coronary artery disease.

Despite McArdle disease primarily affecting skeletal muscle, cardiac involvement has been observed, especially coronary artery disease, the frequency of which was moreover found to be higher in McArdle patients than in the background population in a previous study from a European registry. Exaggerated cardiovascular responses during exercise and impaired glycolytic metabolism have been speculated as potential contributors. A comprehensive cardiological screening might be recommended for McArdle disease patients to detect and manage cardiac comorbidities. A multidisciplinary approach is crucial to effectively manage both neurological and cardiac aspects of the disease and improve patient outcomes. Further research is required to establish clearer pathophysiological links between McArdle disease and cardiac manifestations in order to clarify the existing findings.