Abstract
Introduction
A 67-year-old man was referred for care of "asymptomatic hypertrophic cardiomyopathy". He did not have hypertension. No significant positive family history could be elicited. Electrocardiogram showed sinus rhythm with voltage criteria of left ventricular hypertrophy (LVH). Outside Transthoracic Echocardiogram (TTE) reported normal ejection fraction with asymmetric septal hypertrophy without outflow obstruction. He was put on observation for few years and was not any treatment. On first encounter in our clinic, physical examination including skin and eye assessment, and laboratory tests including renal function were unremarkable.
Procedure
TTE was repeated in our clinic showing normal left ventricular size with ejection fraction 55%, and impaired diastolic relaxation. There was asymmetric septal hypertrophy with septal thickness 2.1 cm (Figure A). There was mild systolic anterior motion of mitral apparatus and mild mitral regurgitation, without resting or Valsalva provoked outflow obstruction. Global longitudinal strain was -7.7% with most prominent abnormalities seen at apex, mid to basal anteroseptal and anterior wall (Figure B). Further assessment by Cardiac MRI showed similar asymmetric septal wall thickening. Late gandolinium enhancement study demonstrated patchy fluffy hyperenhancement of the mid wall of the basal to mid anteroseptal segment, and mid to apical anterior segment, suggestive of myocardial fibrosis (Figure C1 and C2).
Dried spot blood was sent to Taiwan for enzyme study which revealed partial acid alpha-galactosidase A deficiency. Further genetic study detected a mutation of Hemizygous NM_000169.2(GLA):c.640-801[G > A] at intron 4. Finally endomyocardial biopsy was done which confirmed the cardiac involvement of Fabry disease (Figure D, myelin body shown under electron microscopy). This gentleman was referred for consideration of Enzyme Replacement Therapy (ERT).
Discussion
Fabry disease is an X-linked glycolipid storage disease with accumulation of globotriaosylceramide in lysosomes in multiple cell types throughout the body leading to various organ involvement. Cardiac manifestations include unexplained LVH, valvular regurgitation, conduction abnormalities etc. It occurs in up to 0.3-5% of patients with hypertrophic cardiomyopathy. Fabry disease should be considered as a differential diagnosis in all men with sporadic or non-autosomal dominant transmission of unexplained LVH, since treatment with ERT is available which may reduce LVH and improve myocardial function, although any impact on long term outcome has not yet been established.
Conclusion
This case illustrated a rare but potentially treatable cause of hypertrophic cardiomyopathy. Myocardial strain imaging should be integrated in routine TTE study for assessment of unexplained left ventricular hypertrophy. Multi-modality imaging and multi-specialty approach help in identifying patients of cardiac variant of Fabry disease who may benefit from ERT.
Abstract P873 Figure.
P873 A rare and potentially treatable cause of left ventricular hypertrophy
