Clinical Investigation
Congestive Heart Failure
Characteristics and outcomes of cardiomyopathy in children with Duchenne or Becker muscular dystrophy: A comparative study from the Pediatric Cardiomyopathy Registry

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Objective

The aim of this study was to determine in pediatric Duchenne (DMD) and Becker muscular dystrophy (BMD) or other dilated cardiomyopathies (ODCM) whether outcomes differ by diagnosis.

Background

Children with dilated cardiomyopathy are treated as a single undifferentiated group.

Methods

This cohort study of 128 children with DMD, 15 with BMD, and 312 with ODCM uses outcome measures of left ventricular (LV) size and function, death, heart transplant, and death or transplant.

Results

At cardiomyopathy diagnosis, the DMD and BMD groups had similar mean ages (14.4 and 14.6 years), prevalence of congestive heart failure (CHF) (30% and 33%), and LV fractional shortening (FS) Z-scores (median, −5.2 for DMD and −6.7 for BMD). The BMD group had more severe mitral regurgitation (P = .05) and a higher mean LV end-diastolic dimension Z-score than the DMD group (2.9 ± 1.5 vs 1.2 ± 1.9, P = .002). Duchenne muscular dystrophy group survival was lower than in BMD or ODCM groups (P = .06) at 5 years (57%, 100%, and 71%, respectively). In BMD, 25% received cardiac transplants within 0.4 years of cardiomyopathy diagnosis. The combined DMD and BMD group had less LV dilation and a closer-to-normal LV FS at cardiomyopathy diagnosis than the ODCM group. After 2 years, LV dilation increased, and LV FS did not change in the combined DMD and BMD group; for ODCM patients, LV dilation did not progress, and LV FS improved.

Conclusions

Children with DMD and cardiomyopathy have a higher mortality. Becker muscular dystrophy has a high heart transplantation rate in the 5 years after diagnosis of cardiomyopathy. Serial echocardiography demonstrates a different disease course for DMD and BMD patients compared with ODCM patients.

Section snippets

The Pediatric Cardiomyopathy Registry

This report is based on PCMR data as of April 2005 on 3045 patients (newborn to 18 years at diagnosis) who presented with cardiomyopathy to a pediatric cardiologist in 1990 or later. Each case is classified according to morphology as dilated, hypertrophic, restrictive, mixed, or other type of cardiomyopathy. Cases are further classified as “definite” if specified quantitative strict echocardiographic criteria of left ventricular (LV) dilation and systolic dysfunction are met, if the pattern of

Comparison of DMD and BMD Groups

The DMD and BMD groups had a similar age at cardiomyopathy diagnosis (14.4 ± 2.3 vs 14.6 ± 2.0 years) and rates of CHF at diagnosis (30% vs 33%) (Table I).

Echocardiographic findings

At the time of cardiomyopathy diagnosis, the BMD group had larger LV end-diastolic and LV end-systolic dimension Z-scores than did the DMD group (Table II) but similar LV fractional shortening (FS) and LV wall thickness. Although qualitative echocardiographic data were available for only 40 of the 143 children with DMD or BMD, the BMD group

Echocardiographic findings

Patients with BMD do not usually experience marked cardiomyopathy as children, but when they do, they present with a higher degree of mitral and tricuspid regurgitation, LV dilation, and CHF than do children with DMD. Because BMD children have fewer neuromuscular symptoms until they reach older ages, they may not be diagnosed until they present with CHF or cardiac symptoms.

Children and adolescents with ODCM had a higher incidence of CHF at the time of diagnosis than did those in the DMD + BMD

Conclusion

We have shown that a subset of patients with DMD and BMD has clinically important cardiac dysfunction during childhood and that BMD patients have more severe LV dilation and valvular regurgitation at the time of presentation with cardiomyopathy than do DMD patients. The mortality rate for DMD patients with cardiomyopathy is significantly worse than that of BMD patients (who often undergo transplant) and similarly aged myocarditis and idiopathic dilated cardiomyopathy patients; however, rates of

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This study was supported by the National Heart, Lung, and Blood Institute/Department of Health and Human Services grant R01 HL53392, Bethesda, MD, the Children's Cardiomyopathy Foundation, Tenafly, NJ, and the Muscular Dystrophy Association, Tuscon, AZ.

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