Myocardial Fibrosis in Glycogen Storage Disease Type III
A 32-year-old man was referred with exertional chest pain. He had been diagnosed with glycogen storage disease type IIIa (GSDIIIa) by liver biopsy in childhood.
Cine cardiovascular magnetic resonance (CMR) demonstrated profound symmetrical hypertrophy (483 g) with impaired systolic function. Gadolinium-diethylene triamine penta-acetic acid (DTPA) rest perfusion demonstrated multifocal first pass mid-myocardial defects and late imaging demonstrated hyperenhancement (Figure) in these and other areas.
Gadolinium-DTPA is an extracellular tracer, and relative myocardial concentrations are higher in regions of interstitial expansion in the washout phase. Such regions demonstrate hyperenhancement on late imaging (5 to 30 minutes). Initially used to demonstrate fibrosis in myocardial infarction, myocardial hyperenhancement has potential to demonstrate focal interstitial expansion in other conditions.
In GSDIIIa, the functional absence of a glycogen debranching enzyme results in intracellular glycogen accumulation; however, cardiac hypertrophy may also result from interstitial expansion. In the liver, fibrosis is universal, although rarely progressive. In this patient, hyperenhancement comprising 30% of total myocardial mass was present with associated rest perfusion defects, strongly suggesting fibrosis. Imaging the interstitium using gadolinium-DTPA in cardiomyopathy is a new area, and the clinical and prognostic implications are promising.
The editor of Images in Cardiovascular Medicine is Hugh A. McAllister, Jr, MD, Chief, Department of Pathology, St Luke’s Episcopal Hospital and Texas Heart Institute, and Clinical Professor of Pathology, University of Texas Medical School and Baylor College of Medicine.
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