Dilated Cardiomyopathy (DCM)
Dilated Cardiomyopathy (DCM) is a type of heart muscle disease affecting the heart’s main pumping chambers. DCM can affect one ventricle or both. Where the left ventricle becomes enlarged and weakened, its ability to pump blood effectively to the rest of the body is reduced. 
Overview:
Definition: Dilation (stretching and thinning) of one or both ventricles, usually the left, leading to systolic dysfunction (poor contraction).
Prevalence: It’s the most common type of cardiomyopathy and a frequent cause of heart failure and heart transplantation.
Causes:
1. Idiopathic (unknown cause) – ~50% of cases
2. Genetic (familial DCM) – ~25–35% of cases
Mutations in genes affecting cytoskeletal or sarcomeric proteins
3. Secondary causes:
Infections: Viral myocarditis (e.g., Coxsackievirus, adenovirus)
Toxins: Alcohol, cocaine, chemotherapy drugs (e.g., doxorubicin)
Metabolic: Thyroid disease, nutritional deficiencies (thiamine, selenium)
Autoimmune: Lupus, sarcoidosis
Pregnancy-related: Peripartum cardiomyopathy
Tachycardia-induced: Chronic rapid heart rate
Pathophysiology:
Ventricular dilation →
Increased end-diastolic volume
Decreased contractile strength (↓ejection fraction)
Compensatory mechanisms:
Neurohormonal activation (RAAS, sympathetic nervous system)
Myocardial remodelling (fibrosis, apoptosis)
Results in:
Progressive heart failure
Arrhythmias
Increased risk of thromboembolism
Clinical Features
Symptoms of heart failure:
Dyspnoea (shortness of breath)
Fatigue
Orthopnoea, paroxysmal nocturnal dyspnoea
Peripheral oedema, ascites
Signs:
Displaced apical impulse (moves more laterally from 4th intercostal space mid axillary line)
S3 gallop
Mitral/tricuspid regurgitation murmurs
Diagnosis:
Echocardiogram: Key test
Dilated ventricles
Reduced ejection fraction (EF < 40%)
Chest X-ray: Cardiomegaly, pulmonary congestion
ECG: Nonspecific changes, conduction delays, arrhythmias, left ventricular hypertrophy
Cardiac MRI: Detects fibrosis, myocarditis
Blood tests: BNP/NT-proBNP (heart failure markers)
Genetic testing: For familial cases
Treatment:
1. Medical management:
Heart failure therapy:
ACE inhibitors / ARBs / ARNIs
Beta-blockers
Aldosterone antagonists (e.g., spironolactone)
Diuretics (for fluid overload)
SGLT2 inhibitors (newer standard therapy)
Anticoagulation: If risk of thrombus (low EF, atrial fibrillation)
Anti-arrhythmics / ICD: For arrhythmia prevention
2. Device therapy
ICD (Implantable Cardioverter Defibrillator): Prevents sudden cardiac death
CRT (Cardiac Resynchronization Therapy): For ventricular dysynchrony
3. Advanced options (if severe)
LVAD (Left Ventricular Assist Device) or BiVAD (biventricular device)
Heart transplant in end-stage cases
4. Lifestyle and Monitoring
Sodium and fluid restriction
Avoid alcohol and toxins
Regular exercise (as tolerated)
Family screening if genetic
Prognosis
Variable — depends on cause and response to treatment
Some cases (e.g., viral, peripartum) can recover function if supported in the acute phase
Chronic DCM may progress to end-stage heart failure
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