Our study indicates that abnormal myocardial function may be present in patients with BMD, despite normal echocardiographic and radionuclide LVEF, pointing to the need for close follow up. TDE was also found to be more accurate and more sensitive than ultrasound and isotopic methods and should be considered in this setting.
Assessment of LV function in patients with suspected cardiomyopathy is commonly performed by echocardiography or radionuclide ventriculography. Routine measurements are, however, load dependent and do not systematically reflect the contractile state of the myocardium. In contrast, myocardial SR determined by TDE is known as an index of contractility independent of myocardial translational motion and loading variations, and is more sensitive than conventional indices.2,3
Using TDE in our study, we first confirmed the presence of LV systolic dysfunction in patients with a known decrease in LVEF and also demonstrated LV systolic dysfunction in BMD patients with normal LVEF. As SRSYS
are respective markers of myocardial systolic and diastolic function, these patients have both types of dysfunction.3
This is concordant with histological findings in BMD patients which have shown diffuse atrophy and fibrosis of both ventricles.1
Moreover, this complication seems to occur early in BMD (mean age in group 2 was 25.6 years), and is independent of the type of dystrophin gene mutation/deletion (data not shown).4
Combined with the possibility of a complete dissociation between muscle and myocardial involvement, this further highlights the need for appropriate and accurate detection of myocardial dysfunction.
This may have important clinical implications. The detection of systolic dysfunction is known as a crucial issue for the prognostic evaluation of patients with cardiomyopathy associated with muscular diseases.5
Since intense exercise may exacerbate myocardial damage via increases in LV pressure and volume overload, our patients were recommended to abstain from engaging in strenuous physical activities. Moreover, the early use of afterload reducing drugs (ACE inhibitors) may provide effective prevention and warrants study.
BMD patients, with either normal or decreased LVEF, may have myocardial systolic and diastolic dysfunction detected by TDE. This method may offer new diagnostic and therapeutic opportunities in the screening and management of these patients, and should be considered in these settings.