Glycogen storage disease type III (GSD III) is an autosomal recessive disease, due to deficiency of glycogen debranching enzyme (GDE), a key enzyme involved in glycogen degradation. Hypertrophic cardiomyopathy is a classical complication in this disease.

We performed a longitudinal study in order to describe the natural history of heart involvement, relationship with genotype and to determine long term follow up related to hypertrophic cardiomyopathy in patients with GSD III.

We included all consecutive patients with GSD III followed in Pitié-Salpêtrière and Antoine Beclere centers and collected clinical, genetic, electrocardiogram and echocardiography data and cardiac events.

37 patients were included in this study (12 males/25 females). Mean age was 22.4 years [1–52]. All patients were in sinus rhythm expect one patient (atrial fibrillation). Electrical left ventricular hypertrophy was found in 16 (43%) patients. Symptomatic heart failure was found in 8 (22%) patients and 1 (3%) patient disclosed left ventricular dysfunction. Left ventricular hypertrophy (LVH) was found in 16 (43%) patients, mostly symmetric and 4 (11%) patients disclosed obstructive hypertrophic cardiomyopathy. Patients essentially developed heart failure with preserved LVEF (HFpEF) which prevalence increased with age. In univariate analysis, nonsense mutations were associated with more LVH than other type of mutations but not in multivariate analysis.

Hypertrophic cardiomyopathy is frequent in patients with GSD3 and is associated with cardiac clinical events, especially HFpEF.