Left ventricular function in adults with muscular dystrophies: genotype-phenotype correlations.

BACKGROUND

Left ventricular dysfunction (LVD) is a clinical manifestation of muscular dystrophy (MD) in adults and an important prognostic factor. However, there is a lack of recommendations concerning cardiac followup of these patients. The aim of this work was to evaluate the prevalence of systolic LVD in adults with MD.

METHODS

The patients, referred from a Neuromuscular Diseases Unit, underwent clinical evaluation, ECG and transthoracic echocardiogram. Serum troponin I and NT-proBNP were also evaluated. Systolic LVD was defined by an ejection fraction of <0.45 and/or shortening fraction of <0.25.

RESULTS

During a one-year period, we evaluated 24 consecutive patients, 16 men, age 33 +/- 12 years (age at myopathy diagnosis 23 +/- 12 years). They had the following MD: dystrophinopathies--four patients (Duchenne: 1, Becker: 3); Steinert myotonic dystrophy--nine patients; limb-girdle myopathies--six patients; facioscapulohumeral (FSH) myopathies--four patients; and one dysferlinopathy (Miyoshi myopathy). The MD diagnosis, based on clinical and histological criteria, was genetically confirmed in 18 cases (75%). Five patients (20.8%) had thoracic pain, four (16.6%) dyspnea and one a history of syncope. ECG abnormalities were present in 14 cases (58.3%). Stolic LVD or left ventricular remodeling were present in six patients (25%): three with dystrophinopathies, one with limb-girdle myopathy, one with FSH dystrophy and one with myotonic dystrophy. Three patients (12.5%) were diagnosed with heart failure according to the European Society of Cardiology criteria. Three of the five patients with left ventricular dysfunction had elevation of NT-proBNP. One patient with Becker dystrophy had slight elevation of troponin I. In patients with systolic LVD or LV remodeling, the mutations identified were: deletion in intron 1 to exon 49 (one Duchenne MD patient) and deletions in exons 45 to 51 (two Becker MD patients) in the dystrophin gene; deletion of D4Z4 repeats in the DFS locus (4q35) (one patient with FSH MD); and 1300-1500 CTG triplet repeats in the DMPK gene (one patient with myotonic dystrophy).

CONCLUSIONS

These results, although preliminary, show that a high percentage of patients with genetically determined skeletal myopathies exhibit cardiac myocyte functional impairment, with severe LVD and heart failure, justifying periodic cardiovascular evaluation. In the future, phenotype-genotype correlations could help to determine the best cardiac surveillance in MD patients.