ECG and imaging manifestations of cardiomyopathy in adults with Duchenne muscular dystrophy

Cardiomyopathy is universally penetrant in young adults with Duchenne muscular dystrophy (DMD), and is increasingly the preponderant cause of death. We describe the ECG, echocardiography and cardiac MRI (CMR) findings associated with this disease, and the level of agreement between imaging modalities, highlighting the obstacles encountered in high rates of failed diagnostic cardiac imaging in our DMD multidisciplinary care centre. We followed all patients attending a Comprehensive Multidisciplinary Adult DMD clinic over 4 years. All attendees underwent transthoracic echocardiography (TTE) and were offered referral for cardiac MRI (CMR). We recorded baseline demographics, ECG characteristics and imaging findings, comparing TTE and CMR derived LVEF. A total of 33 patients enrolled, median age 20, with mean follow-up of 3 years and 3 months. Common ECG abnormalities were dominant R in V1, pathological Q waves and right axis deviation. Mean LVEF was 51 % at enrollment and 45 % at follow-up by TTE. Presence of any degree of mitral regurgitation correlated strongly to left ventricular systolic dysfunction. CMR was completed in just 25 % of patients, all of whom had extensive midwall fibrosis. Of those in whom CMR failed, 52 % were unable to lie flat or position correctly for scanning, predominantly due to muscle contractures. Despite suboptimal TTE imaging in 75 %, there was good agreement in LVEF between CMR and TTE. We found a high rate of failure to complete diagnostic cardiac imaging in this group of patients with impaired mobility predominantly due to fixed flexion deformities, inability to lay flat or to tolerate the scan. Our study highlights the critical need to provided specially trained Echo and CMR sonographers who understand the challenges to optimal quality imaging in these patients, and who are appropriately supported by Health Care Assistants (HCA) who are familiar with careful positioning to facilitate optimal imaging. Never the less, the study highlights the importance of multimodality imaging, and practical strategies to overcome environmental obstacles to diagnostic imaging, to better guide aggressiveness of treatment for DMD and its inherent cardiomyopathy. Key Learning Points. What is already known: • In addition to significant mobility impairment, Duchenne muscular dystrophy (DMD) is associated with development of severe cardiomyopathy in childhood / early adulthood. Due to relatively recent improvements in survival, the evolution of ECG and imaging correlates in adulthood are poorly described. • The accuracy and degree of correlation between transthoracic echocardiography (TTE) and cardiac MRI (CMR) in this cohort is not known. Myocardial fibrosis, not evaluated on TTE, can be seen on cardiac CMR, and is thought to be predictive of earlier and more severe cardiomyopathy phenotype. Its prevalence in this form of cardiomyopathy is unknown. • Patients with DMD are likely to encounter difficulty in achieving diagnostic cardiac imaging due to factors inherent to the condition as well as environmental obstacles, and an optimal strategy for imaging is not well defined in this particular patient group with unique practical challenges and imaging findings. What the study adds: • We describe the typical and common ECG, TTE and CMR findings in an adult cohort of patients with DMD cardiomyopathy, and the barriers to completing these investigations. • Extensive midwall fibrosis was seen on CMR in 100% of patients scanned, supporting the hypothesis of a universally penetrant cardiomyopathy, and a strategy of early pharmacotherapy in all patients, prior to symptom onset. • We report a good degree of correlation between TTE and CMR −derived LVEF, and therefore highlight the importance of multimodality imaging, with an individually tailored approach in this cohort, in order to guide decisions around escalation of treatment, ICD implantation and prognostication.