CORRESPONDENCE: LETTER TO THE EDITOR
Myocardial Late Enhancement in Duchenne and Becker Individuals in the Clinical Milieu
Vincenzo Giglio, MD, PhD*,
Giovanni Camastra, MD and
Gerardo Ansalone, MD, FESC
* Center for Neuromuscular Diseases–Uildm, Prospero Santacroce St., 5, 00167 Rome, Italy (Email: giglio.echo{at}libero.it).
We read with interest the study by Silva et al. (1) of myocardial delayed enhancement (MDE) in patients with muscular dystrophy. This study focuses on 10 patients, 8 Duchenne muscular dystrophy (DMD) and 2 Becker muscular dystrophy (BMD) individuals age 7 to 18 years, 2 having dilated cardiomyopathy (DCM). It raises several issues.
The authors reported a significant correlation between MDE, as a marker of myocardial fibrosis (MF), and low left ventricular ejection fraction (EF) values.
Although only 2 patients had MF and abnormal echocardiography, their EF values were not shown. Similarly, the correlation between EF and MF in the 5 patients with MF and normal echocardiography should be focused on, as a wide variability in EF data (37.3% to 59.3%) was observed.
Correlation between contractile dysfunction and MF seems ambiguous, as 56.2% of dysfunctional segments had MF, whereas 43.8% did not.
Lack of muscle biopsy renders the diagnosis of 4 patients incomplete: Patients #2 and #3 diagnosed as DMD, carrying an in-frame (Becker) deletion. Patients #5 and #6 (siblings) were diagnosed as BMD, despite the absence of muscle biopsy data. In these patients without cardiomyopathy, the differential diagnosis with limb-girdle dystrophy should be considered.
Seven patients had no deletions of the dystrophin gene. Surprisingly, in these patients, screening for duplications or splicing mutations was not performed. Indeed, Patients #1, #5, and #10 (without MF) could have early cardiac involvement undetectable by cardiac magnetic resonance and develop severe DCM (2). Finally, even the youngest patients (Patients #7 and #8) with MF had no screening for mutations.
Regarding the early detection of heart involvement by cardiac magnetic resonance in children, the authors did not cite ultrasound tissue characterization analysis (3) that reveals early occult cardiac involvement in all affected individuals.
The authors should be highly critical in their assumptions, emphasizing the uncertainties of the conclusions, specifically in view of the small study group.
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References
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- Silva MC, Meira ZMA, Campos AFO, et al. Myocardial delayed enhancement by magnetic resonance imaging in patients with muscular dystrophy J Am Coll Cardiol 2007;49:1874-1879.[Abstract/Free Full Text]
- Nigro G, Politano L, Nigro V, et al. Mutation of dystrophin gene and cardiomyopathy Neuromusc Disord 1994;4:371-379.[CrossRef][ISI][Medline]
- Giglio V, Pasceri V, Messano L, et al. Ultrasound tissue characterization detects preclinical myocardial structural changes in children affected by Duchenne muscular dystrophy J Am Coll Cardiol 2003;42:309-316.[Abstract/Free Full Text]
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