Dilated Cardiomyopathy

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Etiology:
- Idiopathic (risk factors; male, black race, family history)
- Alcohol
- Inflammatory (subsequent to myocarditis)
- Collagen vascular disease; SLE, PAN, dermatomyositis, progressive systemic sclerosis
- Infectious post viral (Coxsackie), Chagas disease, Lyme disease, Rickettsial diseases, acute rheumatic fever
- Neuromuscular disease, Duchenne muscular dystrophy, myotonic dystrophy, Friedreich ataxia
- Metabolic uremia, nutritional deficiency (thiamine, selenium, camitine)
- Endocrine thyrotoxicosis DM
- Familial
- Peripartum
- Toxic cocaine, heroine, glue sniffing, organic solvents
- Radiation induced
- Drug chemotherapeutics (adriamycin)
Pathophysiology
- Clinical manifestation
  * Chronic heart failure (CHF)
  * Systematic or pulmonary emboli
  * Arrhythmias
  * Sudden death (major cause of mortality due to fetal arrhythmia)

 Investigations
- 12 lead ECG
  * ST-T wave abnormalities
  * Poor R wave progression
  * Conduction defects (e.g, BBB)
  * Arrhythmias
- Chest X-ray
  * Global cardiomegaly (glubular heart)
  * Signs of CHF
- Echocardiography
  * 4-chamber enlargment
  * Depressed ejection fraction
  * MR and TR secondary to cardiac dilatation

 - Endomyocardial biopsy; not routine, used to diagnose infiltrative RCM and myocarditis, or to rule out a treatable cause
- Angiography, selected patients
Natural History
- Prognosis
  * Depends on etiology
  * Generally inexorable progression
  * Overall once CHF - 50% 5 year survival
  * Cause of death usually CHF or sudden death
  * Systemic emboli are significant source of morbidity 
Management
- Treat underlying disease - e.g, abstinence from EtOH
- Treat CHF, β blockers (e.g, metaprolol, carvedilol) and ACEI (± All receptor inhibitors) to decrease remodeling
- Anticoagulation to prevent thromboembolism (comadin)
  * Absolute - A fib, history of thromboembolism or documented thrombus
  * Clinical practice is to anticogulate if EF < 20%
- Treat symptomatic or serious arrhythmias
- Immunize against influenza and pneumococcus
- Surgical therapy
  * Cardiac transplant - established definitive therapy
  * LVAD
  * Volume reduction surgery (role remain unclear)
  * Cardiomyopathy (latissimus dorsi wrap)

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