Cardiovascular

Cardiomyopathy

Cardiomyopathy is a primary myocardial disorder classified by its structural and functional phenotype; it may present with heart failure, arrhythmia, syncope or a family history and requires specialist phenotyping, aetiological assessment, sudden-death risk review and family screening.

In a nutshell

Cardiomyopathy is a primary myocardial disease classified by phenotype: hypertrophic (thick and stiff, sometimes obstructive), dilated (enlarged and weak), restrictive (stiff and filling-limited) and arrhythmogenic (scar-related ventricular arrhythmia, often with pump failure). Suspect it with unexplained heart failure, exertional syncope, arrhythmia or a family history. Confirm with ECG, echocardiography and specialist cardiac MRI, then assess aetiology, sudden-death risk and relatives.

Classic presentation

A young person has exertional syncope or palpitations and a family history of cardiomyopathy or sudden death; or an adult has otherwise unexplained heart failure with an abnormal ECG and echocardiogram.

Key points

Use a phenotype-first approach, then investigate genetic, inflammatory, infiltrative, toxic, metabolic, pregnancy-related and tachyarrhythmic causes.
Hypertrophic cardiomyopathy causes impaired relaxation and may cause dynamic LV outflow obstruction; the murmur may increase with standing or Valsalva.
Dilated cardiomyopathy causes chamber dilatation and systolic dysfunction; manage reduced ejection fraction using current NICE heart-failure therapy while treating reversible causes.
Cardiac MRI characterises tissue and scar and may change aetiological or arrhythmic-risk assessment.
Exertional syncope, sustained ventricular arrhythmia, cardiac arrest or a concerning family history requires urgent specialist assessment.
NICE TA913 restricts NHS mavacamten to selected adults with symptomatic obstructive HCM and NYHA class 2 to 3 symptoms as add-on to optimised standard care.
First-degree relatives may need ongoing ECG and echocardiographic screening, with targeted cascade testing when a familial pathogenic variant is found.
Exercise and pregnancy advice must be individualised through the cardiomyopathy or inherited-cardiac service.

First-line investigation

12-lead ECG and transthoracic echocardiography, followed by ambulatory rhythm assessment, cardiac MRI and targeted aetiological or genetic testing as indicated.

Management

Recognise instability and sudden-death risk

Escalate cardiac arrest, sustained ventricular arrhythmia, shock, acute pulmonary oedema, severe decompensation or exertional syncope with concerning history for urgent acute or inherited-cardiac assessment.^7,5,3

Define phenotype and cause

Start with ECG and echocardiography; add ambulatory rhythm monitoring, cardiac MRI and targeted blood or genetic testing to define morphology, tissue, rhythm, aetiology and family risk.^1,5,2

Treat heart failure and tailor lifestyle

Use current NICE NG106 heart-failure treatment for reduced ejection fraction, diuretics for congestion and specialist monitoring of renal function, electrolytes, blood pressure and tolerance; individualise diet, alcohol, exercise, pregnancy and driving advice.^5,2,9

Treat obstruction and prevent lethal arrhythmia

Manage symptomatic obstructive HCM through specialist care with optimised standard therapy and consider NICE TA913-eligible mavacamten or septal reduction; assess ICD need using phenotype-specific sudden-death risk and device guidance.^4,10,1,9

Screen relatives and review progression

Refer first-degree relatives for inherited-cardiac or genetics assessment, offer targeted cascade testing when a familial variant is known, and continue review of rhythm, function, symptoms, treatment tolerance and advanced heart-failure needs.^3,2,5

Exam traps

A cardiomyopathy is not diagnosed from an ejection fraction alone; describe morphology, function, tissue and cause.
The hypertrophic murmur can become louder on standing or Valsalva because obstruction is dynamic; the manoeuvre is not a substitute for echocardiography.
Do not treat all hypertrophy as HCM: hypertension, aortic stenosis, athlete's heart and infiltrative disease require different reasoning.
A normal initial genetic test does not exclude familial disease; relatives may still need clinical screening.
Do not use a generic heart-failure pathway alone for arrhythmogenic or restrictive disease, where arrhythmic and systemic causes may dominate.

Illustrations

ECG in hypertrophic cardiomyopathyTwelve-lead ECG from hypertrophic cardiomyopathy showing high precordial voltages and prominent repolarisation abnormalities, with a reminder that ECG findings support but do not establish the phenotype alone.W.G. de Voogt, MD, PhD, SLAZ, The Netherlands, Wikimedia Commons · CC-BY-SA-3.0

Key sources

This page is exam revision material, not medical advice, and must not be used for patient care. Always check drug doses against the BNF and current guidance. Full disclaimer.