Management of Elevated Troponin in Duchenne Muscular Dystrophy (DMD)
Patients with Duchenne muscular dystrophy who present with elevated troponin levels require immediate cardiac evaluation and management with ACE inhibitors or ARBs, with consideration for adding eplerenone when early cardiomyopathy is detected. 1
Initial Assessment
- Obtain immediate cardiology consultation for comprehensive cardiac evaluation, including electrocardiogram and echocardiogram 1
- Elevated troponin in DMD patients indicates myocardial damage that may be present even in subclinical stages of cardiac involvement 2, 3
- Consider cardiac MRI with late gadolinium enhancement (LGE) as the preferred imaging modality to assess cardiac status, as it provides superior information on tissue characteristics, chamber dimensions, and function 1
- Troponin I levels correlate with cardiac MRI findings and can identify early disease progression - levels are significantly increased in patients with mild LGE compared to those without LGE 4
Pharmacological Management
- Initiate ACE inhibitors (such as perindopril or lisinopril) or ARBs (such as losartan) as first-line therapy for cardioprotection, even in patients with preserved left ventricular function 1, 5
- Consider adding eplerenone (a mineralocorticoid receptor antagonist) to ACE inhibitor or ARB therapy in patients with early cardiomyopathy, as it has been shown to slow the rate of decline in left ventricular function 1, 5
- Be cautious with medication titration, as DMD patients typically have lower systolic blood pressure, especially in advanced stages 1
- Beta-blocker therapy should be considered after initiation of ACE inhibitor/ARB therapy, particularly in patients with ventricular dysfunction or elevated heart rate 1
Monitoring and Follow-up
- Schedule regular cardiac evaluations with annual electrocardiograms and echocardiograms 1
- Consider serial troponin I measurements using high-sensitivity assays to monitor disease progression 3, 4
- Monitor for arrhythmias, as DMD patients with advanced cardiomyopathy may develop atrial fibrillation/flutter, ventricular tachycardia, and ventricular fibrillation 1
- For patients with LV ejection fraction <35%, consider ICD placement following adult heart failure guidelines, but weigh benefits against increased risks due to kyphoscoliosis and respiratory muscle weakness 1
Special Considerations
- Assess respiratory function alongside cardiac evaluation, as respiratory and cardiac involvement often progress in parallel 1
- Measure forced vital capacity (FVC), maximal inspiratory pressure (MIP), maximal expiratory pressure (MEP), and peak cough flow (PCF) to evaluate respiratory status 1
- Consider preoperative training in non-invasive positive pressure ventilation (NPPV) for patients with FVC <50% of predicted who may require procedures 1
- Discuss advance directives and attitudes toward mechanical ventilation and other interventions early in the disease course 1
Advanced Therapies
- For advanced DMD cardiomyopathy, mechanical circulatory support may be considered in select cases as a bridge to transplantation or destination therapy 1
- The risks of ventricular assist device placement may be higher in DMD patients with kyphoscoliosis and respiratory muscle weakness 1
- Establish long-term patient/family/physician relationships to facilitate discussions about goals of care before urgent need for advanced therapies arises 1
Pitfalls and Caveats
- Do not rely solely on symptoms to guide management, as typical heart failure symptoms like exercise limitation or dyspnea may be absent or masked by skeletal muscle weakness 1
- Normal ECG and echocardiogram findings do not exclude the possibility of cardiac complications 1
- Troponin elevation in DMD may reflect ongoing myocardial damage even in the absence of acute coronary syndrome 2, 3
- The pattern of cardiac involvement in DMD (inferolateral) may limit the effectiveness of certain interventions like cardiac resynchronization therapy 1