Duchenne (DMD) and Becker (BMD) muscular dystrophies are hereditary diseases linked on X chromosome. Thus, manifestation of skeletal muscle wasting, but also cardiomyopathy occurs in males, while female carriers of the defective DMD gene are perceived healthy. Nevertheless, they have only one functional variant of the gene on one of the X chromosomes.
In male patients, dystrophy has prevalence of 1/3500–6000 (Mah et al., 2014) affects primarily skeletal muscles, but also heart impairment may occur as a cardiomyopathy (McNally, 2007). Cardiac involvement manifests as progressing decline in diastolic function, systolic ejection fraction, and fractional shortening (Markham et al., 2006). Related is myocardial fibrosis, with muscle contraction impairment (Panovský et al., 2019)
There is number of proposed mechanisms of the disease etiology, primary sarcolemmal tears (Danialou et al., 2001) as consequence of non-functional dystroglycan complex has number of consequences, e.g. increase oxidative stress, ion channel disturbances as well as numerous molecular pathways alteration (Berry et al., 2013; Jelinkova et al., 2019; Mu et al., 2015) eventually leading to impaired heart muscle regeneration, possibly due to stem cell depletion (Pesl et al., 2020). The severity of cardiomyopathy is not always in correlation with skeletal myopathy and cardiac impairment occurs long before clinical symptoms (Li et al., 2009). In female carriers, the clinical symptoms are mostly not presented, thus cardiac function has not been studied in depth. Nevertheless, in case studies were published severe heart failure episodes in different settings as peripartum cardiomyopathy, perioperative stress and others (Cheng and Prior, 2013; Finsterer et al., 2018; Florian et al., 2016; Kerr et al., 2001; Papa et al., 2016), possibly leading even to heart transplantation (Melacini et al., 1998). Still complex prospective randomized studies are missing.
In our previously published study (Panovský et al., 2019) in young males with manifest Duchenne dystrophy we used cardiac magnetic resonance (CMR) to assess the cardiac function and early signs of affection of the heart by T1 mapping because echocardiography has some difficulties due to skeletal deformities and narrow intercostal spaces. Female carriers do not present rib cage anomalies, thus we used echocardiography with tissue Doppler imaging as first line method to assess subclinical cardiac dysfunction. The aim of this study is to assess detectable changes of tissue Doppler parameters in comparison with healthy control subjects.