Cardiac Pathology in Glycogen Storage Disease Type III.
PURPOSE: To investigate the distribution and clinical impact of glycogen accumulation on heart structure and function in individuals with GSD III. METHODS: We examined cardiac tissue and the clinical records of three individuals with GSD IIIa who died or underwent cardiac transplantation. Of the two patients that died, one was from infection and the other was from sudden cardiac death. The third patient required cardiac transplantation for end-stage heart failure with severe hypertrophic cardiomyopathy. RESULTS: Macro- and microscopic examination revealed cardiac fibrosis (n = 1), moderate to severe vacuolation of cardiac myocytes (n = 3), mild to severe glycogen accumulation in the atrioventricular (AV) node (n = 3), and glycogen accumulation in smooth muscle cells of intramyocardial arteries associated with smooth muscle hyperplasia and profoundly thickened vascular walls (n = 1). CONCLUSION: Our findings document diffuse though variable involvement of cardiac structures in GSD III patients. Furthermore, our results also show a potential for serious arrhythmia and symptomatic heart failure in some GSD III patients, and this should be considered when managing this patient population.