Key Facts

Dilated cardiomyopathy (DCM) is characterised by left ventricular (or biventricular) dilatation with impaired systolic function, in the absence of coronary artery disease or abnormal loading conditions sufficient to explain the degree of dysfunction. It is the most common form of cardiomyopathy.

Epidemiology

• Prevalence: ~1 in 250-500
• Most common cardiomyopathy; accounts for ~50% of cardiomyopathies
• Most common indication for heart transplantation
• Male:female ~3:1; peak incidence 20-50 years

Aetiology

• Idiopathic: ~50% (though genetic testing increasingly identifies mutations)
• Genetic/familial: ~25-30%; autosomal dominant most common
  • TTN (titin): most common mutation (~25% of familial DCM)
  • LMNA (lamin A/C): associated with conduction disease and arrhythmias
  • Other: MYH7, TNNT2, SCN5A, DES, BAG3
• Previous myocarditis: viral (Coxsackie, parvovirus B19) — may be post-inflammatory DCM
• Alcohol: significant contributor; potentially reversible with abstinence
• Peripartum cardiomyopathy: last month pregnancy to 5 months postpartum
• Tachycardia-induced: persistent tachycardia (AF, SVT) → reversible if rate controlled
• Drugs/toxins: anthracyclines (doxorubicin), cocaine, amphetamines
• Endocrine: thyroid disease (hyper/hypothyroidism), phaeochromocytoma
• Nutritional: thiamine deficiency (wet beriberi), selenium deficiency (Keshan disease)
• Infiltrative: may overlap with restrictive cardiomyopathy (sarcoidosis, haemochromatosis)

Pathophysiology

• Myocyte loss and fibrosis → ventricular dilatation → reduced contractility (systolic dysfunction)
• Volume overload from regurgitation (functional MR/TR) → further dilatation
• Neurohormonal activation: RAAS, sympathetic → maladaptive remodelling
• Elevated filling pressures → pulmonary and systemic congestion (heart failure)
• Dilated chambers → intracardiac thrombus risk
• Electrical remodelling → arrhythmias (AF, VT/VF)

Typical Presentation

• Heart failure symptoms: dyspnoea (exertional, orthopnoea, PND), fatigue, ankle swelling
• Palpitations (AF, VT)
• Syncope (arrhythmia-related)
• Thromboembolic events (stroke, peripheral embolism)
• May be discovered incidentally on screening

Examination Findings

• Displaced, diffuse apex beat (LV dilatation)
• S3 gallop, elevated JVP, pulmonary crepitations
• Functional mitral regurgitation (pansystolic murmur)
• Peripheral oedema, hepatomegaly, ascites (if biventricular failure)
• Cool peripheries (low cardiac output)

Red Flags

• Progressive heart failure symptoms despite treatment
• Ventricular arrhythmias or syncope
• Family history of sudden death or DCM (screen relatives)
• Young patient with unexplained heart failure
• Conduction disease + DCM (consider LMNA mutation)

Bedside

• ECG: sinus tachycardia, AF, LBBB, poor R-wave progression, low voltage; may show ventricular ectopy
• CXR: cardiomegaly, pulmonary congestion, pleural effusions

Bloods

• BNP/NT-proBNP: elevated (severity and prognosis marker)
• FBC, U&Es, LFTs: baseline
• TFTs: thyroid dysfunction
• Iron studies, ferritin: haemochromatosis
• Glucose/HbA1c: diabetes
• Vitamin B1 (thiamine): if nutritional deficiency suspected
• Viral serology: if recent myocarditis suspected
• Autoimmune screen: if connective tissue disease features

Imaging

• Echocardiography: LV dilatation, reduced LVEF, global hypokinesis, functional MR/TR, LA dilatation
• Cardiac MRI: gold standard for volumes and function; late gadolinium enhancement pattern (mid-wall fibrosis in DCM); excludes ischaemic cause, myocarditis, sarcoidosis
• Coronary angiography: essential to exclude ischaemic aetiology

Special Tests

• Genetic testing: recommended for all DCM patients (especially familial, young onset, conduction disease)
• Family screening: ECG + echocardiography for first-degree relatives (repeat every 2-5 years)
• Endomyocardial biopsy: rarely needed; consider for suspected giant cell myocarditis, sarcoidosis, or haemochromatosis
• Holter monitor: arrhythmia assessment

Non-pharmacological

• Sodium restriction (<6g/day), fluid restriction (1.5-2L/day if hyponatraemic)
• Regular moderate exercise (cardiac rehabilitation)
• Alcohol abstinence (especially if alcoholic CM)
• Daily weights, self-monitoring

Pharmacological

NICE NG106 heart failure management (pillars of therapy):

• ACEi (ramipril 1.25-10mg OD) or ARB (candesartan 4-32mg OD) — if ACEi intolerant
• Beta-blocker: bisoprolol 1.25-10mg OD, carvedilol 3.125-25mg BD, or nebivolol 1.25-10mg OD
• MRA: spironolactone 25-50mg OD or eplerenone 25-50mg OD (RALES, EMPHASIS-HF trials)
• SGLT2 inhibitor: dapagliflozin 10mg OD or empagliflozin 10mg OD (DAPA-HF, EMPEROR-Reduced trials)
• Diuretics: furosemide 20-120mg OD for congestion (symptom relief, not mortality benefit)
• Sacubitril/valsartan (ENTRESTO): replace ACEi/ARB if still symptomatic (PARADIGM-HF trial); require 36-hour ACEi washout
• Hydralazine + ISDN: if ACEi/ARB contraindicated (especially in Black patients — A-HeFT trial)
• Ivabradine: if HR >70 bpm on max beta-blocker in sinus rhythm (SHIFT trial)
• Anticoagulation: if AF, intracardiac thrombus, or prior embolism

Surgical/Interventional

• ICD: if LVEF ≤35% despite ≥3 months OMT, NYHA II-III (primary prevention — NICE TA314)
  • LMNA mutation: lower threshold for ICD (high arrhythmia risk)
• CRT-D or CRT-P: if LVEF ≤35%, LBBB ≥150 ms, NYHA II-IV despite OMT
  • CARE-HF, COMPANION trials: mortality reduction with CRT
• Heart transplantation: end-stage DCM refractory to all therapies
• LVAD (left ventricular assist device): bridge to transplant or destination therapy

Referral Criteria

• All new DCM: cardiology referral for investigation and management
• LVEF ≤35%: specialist HF team for device therapy assessment
• Family history of DCM/SCD: genetics and family screening referral
• End-stage HF: transplant/LVAD assessment

• 5-year survival: ~50-60% overall (improving with modern therapy)
• ~25-30% improve LV function on optimal medical therapy (reverse remodelling)
• Alcohol-related DCM: significant recovery possible with abstinence (~40-50% improve)
• Peripartum DCM: ~50% recover LV function within 6-12 months; recurrence risk in future pregnancies
• Tachycardia-induced DCM: often fully reversible with rate/rhythm control
• LMNA mutations: higher risk of sudden death and need for ICD
• Predictors of poor outcome: severe LV dysfunction, persistent NYHA III-IV, low BP, renal impairment, high BNP

NYHA Functional Classification

Key Heart Failure Trials