Miho Saito

Cardiac dysfunction with Becker muscular dystrophy

Cardiac function was examined in 21 patients with Becker muscular dystrophy (BMD) and compared with 43 patients with Duchenne muscular dystrophy (DMD) and 37 healthy control subjects. Electrocardiography showed myocardial damage was most frequently found in the lateral wall, compatible with autopsy findings. The ratio of the preejection period to the ejection time was higher in patients with BMD (0.37 +/- 0.07, mean +/- SD) than in patients with DMD (0.28 +/- 0.05) and healthy controls (0.23 +/- 0.04). Left ventricular dimension and mitral annular size at end diastole in patients with BMD increased to 52.3 +/- 7.7 mm and 28.8 +/- 5.3 mm with age, respectively. In patients with cardiac failure and BMD, mitral regurgitation was observed at a rate of 66.7%. No definite relation between the deleted locus of the dystrophin gene and cardiac failure was found. Because motor dysfunction progresses more slowly in BMD than in DMD, a prolonged work load on the morbid myocardium may lead to dilated cardiomyopathy with mitral regurgitation.

Detection and management of cardiomyopathy in female dystrophinopathy carriers

Regular health checkups for mothers of patients with Duchenne muscular dystrophy have been performed at National Hospital Organization Tokushima Hospital since 1994. Among 43 mothers participated in this study, 28 dystrophinopathy carriers were identified. Skeletal and cardiac muscle functions of these subjects were examined. High serum creatine kinase was found in 23 subjects (82.1%). Obvious muscle weakness was present in 5 (17.8%) and had progressed from 1994 to 2015. Cardiomyopathy was observed in 15 subjects (60.0%), including dilated cardiomyopathy-like damage that was more common in the left ventricular (LV) posterior wall. Late gadolinium enhancement on cardiac MRI was found in 5 of 6 subjects, suggesting fibrotic cardiac muscle. In speckle tracking echocardiography performed seven years later, global longitudinal strain was decreased in these subjects, indicating LV myocardial contractile abnormality. These results suggest that female dystrophinopathy carriers should receive regular checkups for detection and treatment of cardiomyopathy, even if they have no cardiac symptoms.