Re-examination of the Electrocardiogram in Boys With Duchenne Muscular Dystrophy and Correlation With Its Dilated Cardiomyopathy.

Clinical red flags in dilated cardiomyopathies Electrocardiographic changes in patients with Dystrophin gene defects.

01 Feb 2009

Dystrophin (DYS) gene defects may cause Duchenne Muscle Dystrophy (DMD), Becker Muscle Dystrophy (BMD) and X-linked DCM (X-DCM), with or without increased serum Creatin-Phospho-Kinase (sCPK). Both patients with BMD plus DCM and X-linked DCM may reach the clinical attention for cardiologic rather than myology problems. In consecutive series of males with DCM, about 7% are affected by Dystrophin defects (1). The specific diagnosis of DCM caused by DYS gene defects can be missed unless specifically investigated. Red flags that may help diagnostic orientation are the DCM phenotype, the male gender, the increased sCPK and ECG changes, whose specificity however is not confirmed. The known ECG finding in these patients are short PR interval, right ventricular hypertrophy (RVH), prolonged QTc interval, and prominent Q waves in leads I, aVL, V5, and V6 or in leads II, III, aVF, V5, and V6.

Topic(s):

Myocardial Disease

In the January issue of the Am J Cardiol, Thrush et al from the Ohio State University, Columbus published the manuscript entitled “Re-examination of the Electrocardiogram in Boys With Duchenne Muscular Dystrophy and Correlation With Its Dilated Cardiomyopathy” (2). The search for clinical “red flags” that may guide cardiologists to specific diagnoses in cardiomyopathies is a major aim of our Working Group. In this manuscript, the Authors revised the electrocardiographic changes of 115 patients with Duchenne Muscle Dystrophy (DMD). Based on the echocardiographic criterion of echocardiographic ejection fraction <55%, the authors diagnosed DCM in 40 patients. Comparing ECG of patients with and without DCM they found no differences between the number of ECG changes in DCM and non-DCM groups (p = 0.279) (table below).

Table 1

The authors conclude “ECG changes are similar in patients with DMD regardless of presence of DCM. The most common findings are short PR interval and RVH. Prominent Q waves in leads II, III, aVF, V5, and V6 are more likely”. Therefore, in DMD, ECG changes are not-specifically present in patients with DCM. The short PR interval deserves attention as poorly outlined in the clinical evaluation as potential ECG marker of myocardial involvement in DYS-related phenotypes. Whether a short PR could constitute an ECG marker of mild BMD with DCM and X-DCM associated with Dystrophin defects could be matter of joint evaluation in our working group. Prominent Q waves are better known ECG markers: Q waves in the lateral leads seem to be much more common than in the inferior leads.

fAlthough in DMD ECG changes do not discriminate patients with and without DCM (2), the ECG changes may assume the role of Dystrophin-related disease markers in male patients with DCM. When flanked by increased sCPK, both with and without clinical signs and symptoms of overt myopathy, and X-linked recessive inheritance, ECG changes may contribute to suspect a Dystrophin-related DCM. Patients with DYS gene defects commonly seen first by cardiologists are unlikely to be affected by DMD, which is a paediatric diagnosis, well clinically recognised. BMD patients without DCM are also unlikely to reach the cardiologic attention before the myologic diagnosis.

The possible differential diagnosis as X-linked DCM could be with Barth syndrome, which is a paediatric disease, and is characterised by left ventricular non-compaction, granulocytopenia, methylglutaconic aciduria, hypocholesterolemia, mild increased sCPK and myopthy, and growth deficiency. Ventricular arrhythmia may develop later on the course of the disease (up to 43% of patients with ≥11 years of age). In Barth syndrome ECG changes are present in 58% of the cases (3).

Table 2

Additional X-linked DCM diseases include Emery-Dreifuss Muscle Dystrophy (EMDM) caused by defects of emerin: patients with EDMD frequently show conduction defects and rare develop DCM. Other X-linked cardiomyopathies, such as Danon, Anderson Fabry Disease typically show HCM phenotypes making unlikely the need for differential diagnosis with DYS-associated DCM.

References

Arbustini E, Diegoli M, Morbini P, Dal Bello B, Banchieri N, Pilotto A, Magani F, Grasso M, Narula J, Gavazzi A, Viganò M, and Tavazzi L. Prevalence and characteristics of dystrophin defects in adult male patients with dilated cardiomyopathy. J Am Coll Cardiol 35:1760-68; 2000
Thrush PA, Allen HD, Viollet L, Mendell JR. Re-examination of the Electrocardiogram in Boys With Duchenne Muscular Dystrophy and Correlation With Its Dilated Cardiomyopathy. Am J Cardiol; 103: 262-265; 2009
Spencer CT, Bryant RM, Day J, Gonzalez IL, Colan SD, Thompson WR, Berthy J, Redfearn SP, Byrne BJ. Cardiac and Clinical Phenotype in Barth Syndrome. PEDIATRICS 118: e337-e346; 2006

The content of this article reflects the personal opinion of the author/s and is not necessarily the official position of the European Society of Cardiology.

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Re-examination of the Electrocardiogram in Boys With Duchenne Muscular Dystrophy and Correlation With Its Dilated Cardiomyopathy.

Clinical red flags in dilated cardiomyopathies Electrocardiographic changes in patients with Dystrophin gene defects.

References