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Long-term observation of cardiac function in Duchenne's muscular dystrophy. Evaluation using systolic time intervals
T Utsunomiya1, H Mori, N Shibuya
1Third Department of Internal Medicine, Nagasaki University School of Medicine, Japan.
Insights
Cardiac dysfunction progresses over time in Duchenne muscular dystrophy (DMD) patients, often independently of skeletal muscle decline. Careful cardiac monitoring is essential for managing DMD progression and preventing heart failure.
Area of Science:
- Cardiology
- Neurology
- Genetics
Background:
- Duchenne muscular dystrophy (DMD) frequently causes cardiac involvement.
- Long-term follow-up data on cardiac function in DMD patients are scarce.
Observation:
- Cardiac function was serially assessed over 2-12 years in 34 DMD patients using systolic time intervals and echocardiography.
- Significant deterioration in PEP/ET and echocardiographic parameters (MSEV, MDEV, D/S ratio) was observed within 5-12 years.
- Cardiac function decline correlated with skeletal muscle dysfunction (Swinyard's stage) in approximately half the patients.
Findings:
- Systolic time intervals (PEP/ET) significantly worsened after 9-12 years.
- Echocardiographic parameters (MSEV, MDEV, D/S ratio) showed significant deterioration by 5 years.
- Correlation between cardiac and skeletal muscle function decline was inconsistent, with some patients exhibiting predominant cardiac issues, including one fatal case of congestive heart failure.
Implications:
- The natural course of cardiac dysfunction in DMD requires long-term monitoring.
- Cardiac deterioration may occur independently of skeletal muscle impairment, necessitating specific cardiac surveillance.
- Identification of 'cardiac type' DMD underscores the need for tailored management strategies focusing on cardiac health.
Abstract:
Cardiac involvement is common in patients with Duchenne type muscular dystrophy (DMD). However, published reports of long-term follow-up studies in the same patients are very rare. The purpose of this study was to clarify the natural course of cardiac dysfunction in DMD, and to analyze the relationship between the deterioration of cardiac function and skeletal muscular function. The cardiac function was serially evaluated for 2-12 years in 34 patients with DMD. The systolic time intervals and echocardiography were used for evaluating the cardiac function. The PEP/ET (pre-ejection period/ejection time) of systolic time intervals significantly deteriorated in 9-12 years (p less than 0.001). The maximal systolic and diastolic endocardial velocity (MSEV and MDEV) and the D/S ratio of echocardiography significantly deteriorated in 5 years (p less than 0.001). The D/S ratio is the ratio of the mean systolic velocity and the mean diastolic velocity of the left ventricular posterior wall. In almost half the patients, the deterioration of these parameters was correlated with that of Swinyard's stage. The Swinyard's functional ability stage demonstrates the grade of the skeletal muscular dysfunction. However, there was no correlation between the deterioration of cardiac function and Swinyard's stage in the other half of the patients. Correlation coefficient in the whole group was 0.32 (p = n.s.) between the PEP/ET and Swinyard's stage, and was -0.15 (p = n.s.) between the D/S ratio and Swinyard's stage. Although the mean left ventricular ejection fraction calculated using echocardiography was slightly decreased for 5 years, no significant change was detected in the whole group. One patient had progressive deterioration of left ventricular function despite mild skeletal muscular dysfunction, and died from congestive heart failure. The cardiac dysfunction was predominant. We named it 'cardiac type' DMD. Since deterioration of cardiac function was not always correlated with deterioration of skeletal muscular function (Swinyard's stage), cardiac function must be carefully monitored in patients with DMD.