Cardiomyopathies

Also known as: Cardiomyopathy

Cardiomyopathies are diseases of the heart muscle itself, in the absence of coronary artery disease, hypertension, or valvular disease sufficient to explain the degree of myocardial dysfunction observed. They are classified by structural and functional pattern.

Dilated cardiomyopathy is the most common form, characterized by ventricular dilation and systolic dysfunction. Causes include idiopathic (a substantial proportion, some of which are ultimately genetic once fully investigated), genetic (numerous genes implicated, often with a family history), ischemic (technically a cause of secondary dilated pattern but often grouped clinically), alcohol related, viral myocarditis, peripartum cardiomyopathy (presenting in the last month of pregnancy or within five months postpartum), tachycardia induced, and chemotherapy related (particularly anthracyclines and trastuzumab).

Hypertrophic cardiomyopathy is predominantly a genetic, autosomal dominant condition affecting sarcomeric proteins, causing asymmetric or symmetric ventricular hypertrophy without an identifiable pressure overload cause. It is an important cause of sudden cardiac death in young, otherwise healthy individuals, including athletes.

Restrictive cardiomyopathy is the least common form, characterized by impaired ventricular filling from increased myocardial stiffness, with relatively preserved systolic function until late in the disease. Causes include amyloidosis (a particularly important and increasingly recognized cause, especially in older adults), sarcoidosis, hemochromatosis, and endomyocardial fibrosis.

Arrhythmogenic right ventricular cardiomyopathy involves fibrofatty replacement of right ventricular myocardium, predisposing to ventricular arrhythmia and sudden death, again particularly relevant in young athletes.

Dilated cardiomyopathy presents with the typical features of heart failure: exertional dyspnea, orthopnea, paroxysmal nocturnal dyspnea, fatigue, and peripheral edema (see Heart Failure entry for full detail). Arrhythmia and thromboembolism from a dilated, poorly contracting ventricle are recognized complications.

Hypertrophic cardiomyopathy is often asymptomatic and detected incidentally or through family screening. When symptomatic, it presents with exertional dyspnea, chest pain, palpitations, presyncope or syncope (particularly concerning, as it may reflect outflow tract obstruction or arrhythmia), and, tragically, sudden cardiac death may be the first presentation in some cases. Examination may reveal a harsh systolic murmur that increases with Valsalva maneuver or standing (reflecting dynamic left ventricular outflow tract obstruction, which worsens with reduced preload) and decreases with squatting, a pattern that helps distinguish it from aortic stenosis.

Restrictive cardiomyopathy presents with predominantly right sided heart failure features: raised jugular venous pressure with a prominent y descent, ascites, peripheral edema, and hepatomegaly, often with relatively preserved exercise tolerance early in the disease compared to the degree of venous congestion present.

Echocardiography is central to diagnosis across all subtypes, characterizing chamber size, wall thickness, and systolic and diastolic function, and typically first distinguishes which category of cardiomyopathy is present. ECG frequently shows abnormalities including voltage criteria for hypertrophy, repolarization changes, or arrhythmia, and is an important screening tool in family members of a patient with a genetic cardiomyopathy.

Cardiac MRI provides detailed tissue characterization and is particularly valuable for identifying myocardial fibrosis, infiltrative disease (amyloidosis, sarcoidosis), and confirming arrhythmogenic right ventricular cardiomyopathy. Genetic testing is increasingly used, particularly for hypertrophic cardiomyopathy and dilated cardiomyopathy with a family history, both to confirm diagnosis and to guide cascade screening of relatives.

Further investigation is directed by the suspected underlying cause once the structural pattern is established: cardiac biopsy in selected cases of suspected myocarditis or infiltrative disease, serum free light chains and fat pad biopsy for suspected amyloidosis, ferritin and genetic testing for hemochromatosis, and ACE level and further imaging for suspected sarcoidosis.

Differentials include hypertensive heart disease, ischemic cardiomyopathy from coronary artery disease, valvular heart disease causing secondary ventricular remodeling, and, for hypertrophic patterns, athlete's heart (physiological hypertrophy in trained athletes, which can be difficult to distinguish and sometimes requires deconditioning and repeat assessment).

Dilated cardiomyopathy is managed with standard heart failure guideline directed medical therapy (see Heart Failure entry), alongside treatment of any identifiable reversible cause, such as alcohol cessation, rate control or rhythm control for tachycardia induced cardiomyopathy, and specific immunosuppression in selected cases of myocarditis. Implantable cardioverter defibrillator or cardiac resynchronization therapy is considered once patients are optimized on medical therapy, guided by ejection fraction and other risk criteria.

Hypertrophic cardiomyopathy management centers on symptom control and sudden death risk stratification. Beta blockers are first-line for symptomatic outflow tract obstruction; non-dihydropyridine calcium channel blockers (verapamil) are an alternative. Disopyramide or, increasingly, cardiac myosin inhibitors (mavacamten) are used for refractory obstructive symptoms. Septal reduction therapy, either surgical myectomy or alcohol septal ablation, is reserved for severe, drug refractory obstructive symptoms. Sudden death risk is formally calculated using validated risk scores, guiding the decision for prophylactic implantable cardioverter defibrillator placement. Strenuous competitive exercise is generally restricted, per current guidelines and individualized specialist assessment.

Restrictive cardiomyopathy management is primarily directed at the underlying cause where identifiable, such as specific amyloidosis directed therapy (tafamidis for transthyretin amyloidosis, chemotherapy for light chain amyloidosis) or chelation for hemochromatosis, alongside cautious diuretic use for congestive symptoms, since these hearts are highly preload dependent and can decompensate with excessive diuresis.

Referral: cardiology for all confirmed or suspected cardiomyopathy; specialist inherited cardiac conditions services for genetic cardiomyopathies, given the need for family screening and risk stratification; heart failure and transplant services for advanced or refractory disease.

Clinical toolsCalculators

BMI GCS EDD Parkland Formula

Corrected Sodium Corrected Calcium Anion Gap Creatinine Clearance Insulin Calculations qSOFA Wells PE Wells DVT CHA₂DS₂-VASc HAS-BLED CURB-65 Centor/McIsaac

Rheumatic Fever

Also known as: Acute rheumatic fever

Rheumatic fever is a delayed, autoimmune complication of group A Streptococcus (Streptococcus pyogenes) pharyngitis, occurring roughly two to four weeks after the initial throat infection.

It results from molecular mimicry, in which antibodies raised against streptococcal antigens cross react with host tissue in the heart, joints, skin, and central nervous system.

It remains a major cause of acquired heart disease in children and young adults in low and middle income settings, where access to prompt treatment of streptococcal pharyngitis is limited.

Recurrent episodes cause cumulative valvular damage, and it is this valvular scarring, known as rheumatic heart disease, that carries the long term morbidity and mortality burden.

Diagnosis is guided by the Jones criteria, which separate major and minor manifestations.

The major criteria are carditis (endocarditis, myocarditis, or pericarditis, often presenting as a new murmur, particularly mitral regurgitation), polyarthritis (classically migratory, affecting large joints), Sydenham chorea (involuntary, irregular movements, often delayed in onset by weeks to months after the preceding infection), erythema marginatum (a evanescent, pink, serpiginous rash with central clearing, typically on the trunk and proximal limbs), and subcutaneous nodules (firm, painless, over extensor surfaces and bony prominences).
The minor criteria include fever, arthralgia (which cannot be counted alongside polyarthritis as a major criterion in the same patient), elevated inflammatory markers (ESR or CRP), and a prolonged PR interval on ECG.

Diagnosis requires evidence of a preceding group A streptococcal infection, together with either two major criteria, or one major plus two minor criteria. A separate, lower threshold applies for recurrent episodes in a patient with known prior rheumatic fever.

Evidence of preceding streptococcal infection is sought through a positive throat culture or rapid antigen test (though these are frequently negative by the time rheumatic fever manifests, given the delay after the original infection), or, more usefully at this stage, elevated or rising anti-streptolysin O (ASOT) or anti-DNase B titres.

Inflammatory markers (ESR and CRP) support the diagnosis as minor criteria and help track disease activity.

ECG is essential, looking for a prolonged PR interval and any arrhythmia.

Echocardiography is required in all suspected cases, both to confirm carditis (which may be subclinical, detected only on echocardiography without an audible murmur) and to assess the severity of any valvular involvement, most commonly mitral regurgitation, less commonly aortic regurgitation.

Differentials include septic arthritis, reactive arthritis, juvenile idiopathic arthritis, systemic lupus erythematosus, viral myocarditis, and infective endocarditis, particularly when carditis is the presenting feature.

Eradication of the streptococcal infection is essential even if throat culture is now negative, using a single dose of intramuscular benzathine penicillin, or oral phenoxymethylpenicillin for ten days if intramuscular treatment is not feasible.

Anti-inflammatory treatment follows separately. Arthritis and fever generally respond well to high dose aspirin or another NSAID (naproxen is a commonly used alternative), continued until symptoms and inflammatory markers settle.

Moderate to severe carditis, particularly with heart failure, is treated with corticosteroids, though evidence for a mortality or long term valvular benefit is limited and steroids are used mainly for symptomatic and hemodynamic control in this context.

Heart failure arising from severe carditis is managed with standard heart failure therapy alongside the anti-inflammatory treatment above (see Heart Failure entry).

Sydenham chorea, when mild, may only require reassurance and supportive care; more significant chorea is treated with carbamazepine or sodium valproate, with antipsychotics reserved for severe, refractory cases.

Secondary prophylaxis is the cornerstone of long term management, given the markedly increased risk of recurrent rheumatic fever and progressive valvular damage with each subsequent episode.

Regular intramuscular benzathine penicillin, typically every three to four weeks, is continued for a minimum duration determined by the presence and severity of carditis: at least five years or until age twenty one for rheumatic fever without carditis, at least ten years or until age twenty five for rheumatic fever with carditis but no residual valvular disease, and lifelong for those with established valvular disease.

Referral: cardiology for all confirmed or suspected carditis, given the need for echocardiographic assessment and monitoring of valvular disease; neurology for significant chorea.

Cardiomyopathies

Overview

Clinical Features

Diagnosis

Management

Overview

Clinical Features

Diagnosis

Management