Cardiac pathologies in female carriers of Duchenne muscular dystrophy assessed by cardiovascular magnetic resonance imaging

Dystrophinopathies are due to mutations in the dystrophin gene on chromosome Xp21.1 and comprise the allelic entities Duchenne muscular dystrophy (DMD), Becker muscular dystrophy (BMD) and X-linked dilative cardiomyopathy (XLDCM). In all three entities, the heart is affected to various degrees, depending on the stage of the disease and the type of the mutation (cardiac involvement, CI). The pathoanatomic evidence of CI in dystrophinopathies is the replacement of myocardium by connective tissue or fat. In DMD/BMD, the left ventricular posterobasal and lateral walls are most extensively affected, sparing the right ventricle and the atrium. Degree and dynamics of CI vary among the three entities. In DMD/BMD, CI usually remains subclinical in the early stages of the disease. Typical initial manifestations of CI in DMD/BMD are sinus tachycardia, tall R1 in V1, prominent Q in I, aVL, V6 or in II, III, and aVF, increased QT dispersion and possibly autonomic dysfunction. Initially, echocardiography is normal or shows regional wall motion abnormalities in areas of fibrosis. With spreading of fibrosis, left ventricular dysfunction and ventricular arrhythmias additionally occur. In the final stages of the disease, systolic function may lead to heart failure and sudden death. Subclinical or clinical CI is present in about 90% of the DMD/BMD patients but is the cause of death in only 20% of the DMD and 50% of the BMD patients. XLDCM is a rapidly progressive, almost exclusively myocardial disorder, starting in teenage males as heart failure due to dilative cardiomyopathy (CMP), leading to death from intractable heart failure within 1–2 years after diagnosis. Therapy of arrhythmias and CMP in all three disorders follows the established cardiological recommendations. Due to its protective effect, ACE inhibitors are recommended already at the early stages of the disease. β-Blockers may be an additional option if indicated.

This study sought to analyze whether cardiovascular magnetic resonance (CMR) can detect and quantify myocardial damage in the early stages of cardiomyopathy in muscular dystrophies (MD). Muscular dystrophy is a genetic disease that involves skeletal and cardiac tissues of humans. Cardiomyopathy is common, and death secondary to cardiac or respiratory diseases occurs early in life. Cardiovascular magnetic resonance is a reliable method for assessing global and regional cardiac function, allowing also for the detection of myocardial fibrosis (MF). Ten patients with Duchenne or Becker dystrophies were studied by CMR. Physical examination, Chagas disease serological tests, electrocardiogram, chest radiograph, total creatine kinase, and Doppler echocardiogram were also obtained in all patients. Patients with MF had a lower ejection fraction than those without. Myocardial fibrosis (midwall and/or subepicardial) was observed in 7 of the 10 patients, and the lateral wall was the most commonly involved segment. There was moderate correlation between segmental MF and dysfunction. Cardiovascular magnetic resonance can identify MF and may be useful for detecting the early stages of cardiomyopathy in MD. Future work will be needed to evaluate whether CMR can influence cardiomyopathy and outcomes.

Objectives To analyse the value of cardiovascular magnetic resonance (CMR)-derived myocardial parameters to differentiate left ventricular non-compaction cardiomyopathy (LVNC) from other cardiomyopathies and controls. Methods We retrospectively analysed 12 patients with LVNC, 11 with dilated and 10 with hypertrophic cardiomyopathy and compared them to 24 controls. LVNC patients had to fulfil standard echocardiographic criteria as well as additional clinical and imaging criteria. Cine steady-state free precession and late gadolinium enhancement (LGE) imaging was performed. The total LV myocardial mass index (LV-MMI), compacted (LV-MMIcompacted), non-compacted (LV-MMInon-compacted), percentage LV-MMnon-compacted, ventricular volumes and function were calculated. Data were compared using analysis of variance and Dunnett’s test. Additionally, semi-quantitative segmental analyses of the occurrence of increased trabeculation were performed. Results Total LV-MMInon-compacted and percentage LV-MMnon-compacted were discriminators between patients with LVCN, healthy controls and those with other cardiomyopathies with cut-offs of 15 g/m2 and 25 %, respectively. Furthermore, trabeculation in basal segments and a ratio of non-compacted/compacted myocardium of ≥3:1 were criteria for LVNC. A combination of these criteria provided sensitivities and specificities of up to 100 %. None of the LVNC patients demonstrated LGE. Conclusions Absolute CMR quantification of the LV-MMInon-compacted or the percentage LV-MMnon-compacted and increased trabeculation in basal segments allows one to reliably diagnose LVNC and to differentiate it from other cardiomyopathies. Key Points • Cardiac magnetic resonance imaging can reliably diagnose left ventricular non-compaction cardiomyopathy. • Differentiation of LVNC from other cardiomyopathies and normal hearts is possible. • The best diagnostic performance can be achieved if combined MRI criteria for the diagnosis are used.