Abstract
Funding Acknowledgements
Type of funding sources: None.
Background
The incidence of cardiomyopathy in Duchenne muscular dystrophy (DMD) increases with age, accounting for up to 20% of mortality in the third decade of life. As patients are frequently asymptomatic until advanced stages of disease, imaging plays an essential role in screening for cardiac involvement and monitoring progression. Guidelines recommend annual transthoracic echocardiography assessment, with periodic use of cardiac magnetic resonance imaging (CMR). However, some studies suggest that CMR should be the gold standard imaging in DMD. This study aimed to review the use echo and CMR in adult patients with DMD, with particular focus on practical utility and real-world limitations.
Methods
A retrospective chart review of 24 patients attending our DMD cardiomyopathy clinic was undertaken. Demographic data including age, genotyping and medical therapy were noted. Results of cardiac imaging, as well as discussions regarding referral for CMR were recorded.
Results
All patients had echocardiography performed in our facility (table 1) and all had a documented discussion regarding referral for CMR in their medical notes. 15 patients (60%) were unsuitable for CMR and were not referred. Reasons were inability to lie flat due to breathing/claustrophobia (n = 12) and difficulty with positioning due to contractures (n = 9). 2 patients (8%) attended for CMR but were unable to proceed due to difficulty with positioning in the scanner. 4 patients (16.5%) had CMR performed, 3 additional patients were referred and awaited CMR. Results outlined in table 1 and image 1 show correlation between measurement of left ventricular ejection fraction (LVEF) on echo and CMR. Wall motion abnormalities and fibrosis were better detected with CMR.
Conclusion
Significant limitations were seen with both imaging techniques. Accessibility of CMR for adults with DMD is poor, related primarily to the severity of underlying musculoskeletal and respiratory disease. Echocardiography is easily accessible, but images are frequently suboptimal. Despite this, strong correlation was seen in assessment of LV function in those who underwent both echocardiography and CMR, with indication that echocardiography can accurately guide intensification of medications and cardiac device therapy. CMR remains the optimal modality for the assessment of myocardial fibrosis. Improving accessibility of CMR for patients with DMD should be prioritised for the future of this modality.