Enlarged heart, an umbrella finding with many causes and a modern treatment plan.

An enlarged heart, or cardiomegaly, is an imaging finding of increased heart size - typically a cardiothoracic ratio above 50 per cent on chest X-ray with chamber-specific measurements on echocardiography or cardiac MRI. It is a sign, not a diagnosis. The clinical work is identifying the underlying cause, whether that is coronary disease, valve disease, cardiomyopathy, chronic hypertension or a rarer condition such as amyloidosis or sarcoidosis.

The five recognised inherited or acquired muscle diseases are dilated cardiomyopathy, hypertrophic cardiomyopathy, restrictive cardiomyopathy, arrhythmogenic right ventricular cardiomyopathy and left ventricular non-compaction. Each has its own causes, imaging pattern, genetic profile and treatment pathway - which is why cardiac MRI and specialist review matter.

Not always. Some enlargement is physiological, such as athlete's heart in trained endurance athletes. Pathological enlargement, however, is associated with heart failure, arrhythmia and sudden cardiac death, so the correct approach is a structured assessment - history, examination, ECG, echo and often cardiac MRI - to distinguish safe adaptation from underlying disease.

Echocardiography is the workhorse and provides chamber sizes, systolic and diastolic function, wall thickness, valve assessment and pulmonary pressure. Cardiac MRI is the reference standard for morphology and tissue characterisation, particularly for fibrosis on late gadolinium enhancement. Bloods (NT-proBNP, troponin, iron studies, free light chains) and ambulatory monitoring complete the picture.

Modern therapy rests on four pillars - a beta-blocker, an ACE inhibitor or ARNI such as sacubitril-valsartan, a mineralocorticoid receptor antagonist such as spironolactone or eplerenone, and an SGLT2 inhibitor such as dapagliflozin or empagliflozin. NICE now approves SGLT2 inhibitors for heart failure regardless of diabetes status. Device therapy, disease-specific options and cardiac rehabilitation sit on top.

In inherited cardiomyopathies such as HCM, dilated cardiomyopathy with a genetic cause, ARVC and LVNC, first-degree relatives should be offered clinical assessment and, where a pathogenic variant is identified, cascade genetic testing. This is coordinated through a specialist inherited cardiac conditions clinic with structured genetic counselling.