Medically reviewed by Dr Nabila Laskar, Consultant Cardiologist (GMC 7040901). Cardiomyopathy is a disease of the heart muscle itself — not the coronary arteries or valves, but the myocardium. It causes the heart to become enlarged, thickened, or stiffened, impairing its ability to pump effectively.
Dilated cardiomyopathy (DCM) is the most common type — the left ventricle enlarges and weakens, reducing pumping function, with causes including viral infection, alcohol excess, certain medications and genetic factors. Hypertrophic cardiomyopathy (HCM) involves abnormal thickening of the heart muscle, particularly the interventricular septum — see /conditions/hypertrophic-cardiomyopathy. Restrictive cardiomyopathy causes the heart walls to stiffen, impeding filling between beats, most commonly in infiltrative conditions such as amyloidosis. Arrhythmogenic cardiomyopathy (ACM) affects the right ventricle and is associated with life-threatening arrhythmias.
Symptoms vary by type and severity but commonly include breathlessness on exertion or at rest, fatigue, palpitations, chest discomfort, dizziness and syncope. In HCM, symptoms are often brought on by exercise. Cardiomyopathy may also be identified on routine screening before any symptoms develop, which is why echo screening of first-degree relatives is recommended.
Echocardiogram is the cornerstone investigation for all cardiomyopathies. In DCM it quantifies chamber dilation and reduced ejection fraction — see /conditions/ejection-fraction-explained. In HCM it measures septal thickness and identifies outflow obstruction. Genetic testing and cardiac MRI are often added in confirmed cases to characterise the condition and guide management.
Treatment depends entirely on the type and severity. Dilated cardiomyopathy is managed with heart failure medications which can significantly improve ejection fraction over time — see /conditions/heart-failure. HCM management includes medication, lifestyle advice including restrictions on intense competitive sport in some cases, and an implantable defibrillator for high-risk patients. All inherited cardiomyopathies carry implications for first-degree relatives, who should be offered cascade screening.
Hypertrophic cardiomyopathy and arrhythmogenic cardiomyopathy are frequently inherited in an autosomal dominant pattern — meaning first-degree relatives (parents, siblings, children) have a 50% chance of carrying the same genetic variant and should be offered cardiac screening.
This depends entirely on the type and severity. Some cardiomyopathies — particularly HCM — require specific restrictions on intense competitive sport. A cardiologist will advise on safe activity levels based on your individual assessment.
Some forms — particularly dilated cardiomyopathy caused by alcohol or treatable viral myocarditis — can substantially recover with treatment. Others are chronic conditions managed rather than cured, though outcomes have improved significantly with modern treatment.
Echocardiogram is the primary diagnostic tool, often combined with ECG, cardiac MRI, and in inherited forms, genetic testing. It is frequently identified during investigation of breathlessness, palpitations, or family screening.