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Acute myocarditis (Inflammatory cardiomyopathy)
This describes acute inflammation of the myocardium.
It is most commonly due to a viral infection. The most common virus is Coxsackie A and B (although usually the causal virus is not identified).
The most common cause worldwide is Trypanosoma cruzi (Chagas disease).
It can also be due to drugs including ethanol, clozapine and doxorubicin.
Half of patients recover in a month whereas many go on to develop dilated cardiomyopathy and heart failure.
Symptoms
Patients may have signs of a recent viral infection e.g. fever, joint pain, fatigue
Disease mirrors acute coronary syndrome e.g. acute chest pain, palpitations with shortness of breath
Key tests
ECG shows diffuse T wave inversions and saddle-shaped ST elevations
Raised inflammatory markers CRP/ESR with raised troponin and BNP
Heart MRI shows inflammation of the heart muscle
Management
Treat underlying cause, e.g., if parasitic or bacterial then give antibiotics
Anti-inflammatories, e.g., NSAIDs and colchicine, steroids if refractory to treatment
Symptomatic treatment of heart failure and antiarrhythmics
Dilated Cardiomyopathy (DCM)
The most common cardiomyopathy which refers to dilation of all 4 heart chambers.
It gives systolic dysfunction with biventricular heart failure and valve incompetence.
Causes
Usually idiopathic
Acute myocarditis (usually due to Coxsackie A/B)
Haemochromatosis
Ischaemic heart disease
Hypertension
Vitamin B1 deficiency
Drugs – Doxorubicin
Symptoms
Symptoms of heart failure – fatigue, oedema, ascites, S3 gallop heart sounds
Systolic murmur due to mitral/tricuspid regurgitation
Key tests
CXR shows “balloon” appearance of the heart
Echocardiogram shows LV dilation and systolic dysfunction with impaired global contractility
Management
Medications for heart failure (beta-blockers, ACE-i, mineralocorticoid antagonist).
If refractory to medical treatment, the definitive management is heart transplant
Hypertrophic Obstructive Cardiomyopathy (HOCM)
This refers to left ventricular hypertrophy which causes obstruction and turbulence in the left ventricular outflow tract.
It is the leading cause of sudden cardiac death in the young.
It is usually due to a genetic mutation in sarcomere proteins (β-myosin heavy chain).
It is inherited in an autosomal dominant fashion, but also associated with conditions like Friedrich’s ataxia and WPW syndrome.
Hypertrophy means that the ventricle cannot fill in diastole reducing cardiac output.
Symptoms
Can be asymptomatic and lead to sudden cardiac death due to ventricular fibrillation
The outflow tract obstruction gives rise to symptoms of aortic stenosis in young patients, e.g., exertional dyspnoea, angina, syncope following exercise
Gives ejection systolic murmur with jerky pulse
Key tests
ECG shows left ventricle hypertrophy with deep Q waves
Echo shows MR SAM ASH (mitral regurgitation, systolic anterior motion of mitral valve and asymmetric hypertrophy)
Cardiac biopsy shows hypertrophy of the muscle fibres
Management
This involves management of the complications: heart failure (e.g., beta-blockers), atrial fibrillation (rhythm control and anticoagulation), obstructive heart failure (surgical myomectomy) and prevention of sudden cardiac death (ICD).
Restrictive Cardiomyopathy
This is decreased compliance of the ventricular endocardium that restricts filling during diastole. This gives it similar symptoms to constrictive pericarditis.
Causes
Amyloidosis – build-up of amyloid plaques in organs
Haemochromatosis – inherited condition in which iron levels rise over many years
Endomyocardial fibrosis – fibrosis of the endocardium
Loffler’s syndrome – endomyocardial fibrosis with eosinophilic infiltrate and eosinophilia.
Symptoms
Presents as right heart failure –> Increased JVP, hepatomegaly, oedema, ascites
Classic finding is low-voltage ECG with diminished QRS amplitude
Key tests
Echocardiogram
MRI
Management
Treat the underlying cause
