Cardiac Manifestations of Systemic Disease
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Direct answer
Cardiac manifestations of systemic disease are heart abnormalities caused by a non-cardiac condition, such as thyroid dysfunction, diabetes or a connective tissue disorder. Each systemic disease has a typical cardiac lesion, so the lesion often points back to the underlying diagnosis. Thyrotoxicosis causes atrial fibrillation and high-output failure, while hypothyroidism causes pericardial effusion, bradycardia and diastolic dysfunction.
What you must remember
- Thyrotoxicosis: atrial fibrillation and high-output heart failure, which often improve once euthyroidism is restored.
- Hypothyroidism: pericardial effusion, bradycardia, low-voltage ECG and diastolic dysfunction.
- Diabetes: coronary artery disease with silent ischaemia, and diabetic cardiomyopathy with diastolic dysfunction.
- Acromegaly: biventricular hypertrophy, cardiomyopathy, hypertension and valve thickening.
- Haemochromatosis: restrictive or dilated cardiomyopathy and arrhythmias from iron deposition in the myocardium.
- Systemic lupus erythematosus: Libman-Sacks endocarditis, typically a verrucous lesion on the mitral valve, plus pericarditis and myocarditis.
- Duchenne muscular dystrophy: dilated cardiomyopathy with posterolateral left ventricular fibrosis.
- Myotonic dystrophy: conduction block and arrhythmias, with a risk of sudden death.
Linking the lesion to the disease
The heart often reveals a systemic disease before the systemic features are obvious. The table pairs each disorder with its typical cardiac lesion and the clue that points to it.
| Systemic disease | Typical cardiac lesion | Clue that points to it |
|---|---|---|
| Thyroid disease | AF, effusion, heart failure | Weight loss and tremor, or cold intolerance |
| Diabetes | Coronary disease, cardiomyopathy | Silent ischaemia, autonomic neuropathy |
| Acromegaly | Biventricular hypertrophy | Coarse facial features, enlarged hands |
| Haemochromatosis | Restrictive or dilated cardiomyopathy | Bronze skin, diabetes, liver disease |
| Systemic lupus | Libman-Sacks endocarditis, pericarditis | Rash, arthritis, nephritis |
| Duchenne dystrophy | Dilated cardiomyopathy | Boy with proximal weakness, raised CK |
| Myotonic dystrophy | Conduction block, arrhythmias | Myotonia, cataracts, frontal balding |
Thyroid, diabetic and acromegalic changes are often partly reversible once the systemic disease is controlled. Fibrosis in dystrophies and iron deposition in haemochromatosis tend to persist, so early treatment matters more there.
Arrhythmic lesions in neuromuscular disease need early device planning rather than waiting for heart failure to develop.
Where systemic causes get missed
Errors usually come from attributing a cardiac finding to a primary heart disease before the systemic cause is checked.
- Trap: calling new atrial fibrillation idiopathic without checking thyroid function Correct: thyrotoxicosis is a reversible cause and must be excluded first.
- Trap: labelling dilated cardiomyopathy in a boy as idiopathic without checking creatine kinase Correct: Duchenne dystrophy should be considered, because creatine kinase is markedly raised and early heart failure treatment matters.
- Trap: assuming acromegalic cardiac changes resolve completely with cure Correct: some hypertrophy and cardiomyopathy improve after biochemical control, but the improvement is often incomplete.
Frequently asked questions
Which systemic disease causes Libman-Sacks endocarditis?
Systemic lupus erythematosus causes Libman-Sacks endocarditis, a non-bacterial verrucous lesion that most often involves the mitral valve. It is one reason lupus patients with a new murmur need echocardiography, even without fever.
Which thyroid state causes pericardial effusion?
Hypothyroidism causes pericardial effusion, often with bradycardia, low-voltage ECG and diastolic dysfunction. Thyroid hormone replacement is the treatment, and the effusion usually improves once the thyroid state is corrected.
Which valve lesion is typical of ankylosing spondylitis?
Aortic regurgitation with aortic root dilatation is the typical valve lesion of ankylosing spondylitis. It results from aortitis at the root and can progress slowly over many years.
Which neuromuscular disease causes conduction block and arrhythmias?
Myotonic dystrophy causes conduction block and arrhythmias, and it carries a risk of sudden death. Cardiac review with ECG and rhythm monitoring is therefore part of routine care in myotonic dystrophy.