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ALL / Cardiology
Dilated cardiomyopathy
Dilated cardiomyopathy
Dilated cardiomyopathy (DCM) is the most common form of cardiomyopathy, accounting for 90% of cases.Causes:
- idiopathic: the most common cause
- myocarditis: e.g. Coxsackie B, HIV, diphtheria, Chagas disease
- ischaemic heart disease
- peripartum
- hypertension
- iatrogenic: e.g. doxorubicin
- substance abuse: e.g. alcohol, cocaine
- inherited: either a familial genetic predisposition to DCM or a specific syndrome e.g. Duchenne muscular dystrophy
- around a third of patients with DCM are thought to have a genetic predisposition
- a large number of heterogeneous defects have been identified
- the majority of defects are inherited in an autosomal dominant fashion although other patterns of inheritance are seen
- infiltrative e.g. haemochromatosis, sarcoidosis
- these causes may also lead to restrictive cardiomyopathy
- nutritional e.g. wet beriberi (thiamine deficiency)
Pathophysiology
- dilated heart leading to predominately systolic dysfunction
- all 4 chambers are dilated, but the left ventricle more so than right ventricle
- eccentric hypertrophy (sarcomeres added in series) is seen
Features
- classic findings of heart failure
- systolic murmur: stretching of the valves may result in mitral and tricuspid regurgitation
- S3
Investigations
- ECG and chest X-ray to assess arrhythmias, chamber enlargement and pulmonary congestion
- 'balloon' appearance of the heart on the chest x-ray
- transthoracic echocardiography to confirm left ventricular dilatation and systolic dysfunction
- BNP/NT-proBNP to support a diagnosis of heart failure
- coronary angiography or CT coronary angiography when ischaemic aetiology is suspected
- cardiac MRI to evaluate myocardial fibrosis, inflammation or infiltrative disease
- blood tests: FBC, U&E, LFT, TFT, iron studies, autoimmune screen if clinically indicated
- genetic testing in patients with a family history or idiopathic disease
Management
- first-line treatment for all patients with heart failure with reduced ejection fraction (HFrEF) is a combination of the following 4 medications:
- ACE-inhibitor
- beta-blocker
- mineralocorticoid receptor antagonist (MRA)
- SGLT2-inhibitor
- treat the underlying cause where identified (e.g. abstinence from alcohol, iron removal for haemochromatosis)
- loop diuretics for symptomatic fluid overload
- anticoagulation if intracardiac thrombus, atrial fibrillation or other indications are present
- cardiac resynchronisation therapy or implantable cardioverter-defibrillator in eligible patients
- consider heart transplantation in end-stage, refractory disease
+PassMedicine Notes
Dilated cardiomyopathy (DCM) is the most common form of cardiomyopathy, accounting for 90% of cases.
Causes:- idiopathic: the most common cause
- myocarditis: e.g. Coxsackie B, HIV, diphtheria, Chagas disease
- ischaemic heart disease
- peripartum
- hypertension
- iatrogenic: e.g. doxorubicin
- substance abuse: e.g. alcohol, cocaine
- inherited: either a familial genetic predisposition to DCM or a specific syndrome e.g. Duchenne muscular dystrophy
- around a third of patients with DCM are thought to have a genetic predisposition
- a large number of heterogeneous defects have been identified
- the majority of defects are inherited in an autosomal dominant fashion although other patterns of inheritance are seen
- infiltrative e.g. haemochromatosis, sarcoidosis
- these causes may also lead to restrictive cardiomyopathy
- nutritional e.g. wet beriberi (thiamine deficiency)
- dilated heart leading to predominately systolic dysfunction
- all 4 chambers are dilated, but the left ventricle more so than right ventricle
- eccentric hypertrophy (sarcomeres added in series) is seen
- classic findings of heart failure
- systolic murmur: stretching of the valves may result in mitral and tricuspid regurgitation
- S3
- ECG and chest X-ray to assess arrhythmias, chamber enlargement and pulmonary congestion
- 'balloon' appearance of the heart on the chest x-ray
- transthoracic echocardiography to confirm left ventricular dilatation and systolic dysfunction
- BNP/NT-proBNP to support a diagnosis of heart failure
- coronary angiography or CT coronary angiography when ischaemic aetiology is suspected
- cardiac MRI to evaluate myocardial fibrosis, inflammation or infiltrative disease
- blood tests: FBC, U&E, LFT, TFT, iron studies, autoimmune screen if clinically indicated
- genetic testing in patients with a family history or idiopathic disease
- first-line treatment for all patients with heart failure with reduced ejection fraction (HFrEF) is a combination of the following 4 medications:
- ACE-inhibitor
- beta-blocker
- mineralocorticoid receptor antagonist (MRA)
- SGLT2-inhibitor
- treat the underlying cause where identified (e.g. abstinence from alcohol, iron removal for haemochromatosis)
- loop diuretics for symptomatic fluid overload
- anticoagulation if intracardiac thrombus, atrial fibrillation or other indications are present
- cardiac resynchronisation therapy or implantable cardioverter-defibrillator in eligible patients
- consider heart transplantation in end-stage, refractory disease
