Audience: cardiology trainees, imagers and inherited-cardiac-condition teams. Evidence reviewed: September 2026.
Key message
Arrhythmogenic cardiomyopathy (ACM) is a spectrum that may be right-dominant, biventricular or left-dominant. Imaging supports—but does not independently establish—the diagnosis. Electrical, structural, tissue, genetic and family data must be integrated.
When to suspect ACM
- Ventricular arrhythmia with morphology suggesting RV or LV origin.
- Unexplained regional ventricular dysfunction or aneurysm.
- Disproportionate RV dilatation or dysfunction.
- Subepicardial or ring-like non-ischaemic scar on CMR.
- A pathogenic variant or family history of ACM or premature sudden death.
Echocardiography
Perform a complete study with an RV-focused apical view. Assess RV dimensions, fractional area change, TAPSE, S′, free-wall strain and regional motion. Examine the RV outflow tract in parasternal long- and short-axis views. For the LV, quantify volumes and ejection fraction, examine regional deformation and look for subtle inferolateral dysfunction.
Regional akinesia, dyskinesia or aneurysm is more specific than subjective hypokinesia, but normal variants and poor windows are common. Prominent trabeculation or the moderator band is not diagnostic. Isolated mild RV enlargement in an athlete requires careful differentiation using proportional chamber remodelling, function, arrhythmia burden and tissue characterisation.
Cardiovascular magnetic resonance
CMR provides reproducible biventricular volumes and ejection fractions, regional cine assessment and myocardial tissue characterisation. Late gadolinium enhancement can identify non-ischaemic fibrosis; fat-sensitive observations alone are neither sufficiently specific nor central to modern diagnosis. Image quality, arrhythmia and partial-volume effects must be documented.
| Modality | Strength | Limitation |
|---|---|---|
| Echo | Accessible, dynamic haemodynamics, serial follow-up | Geometry and acoustic-window dependence |
| CMR | Volumes, regional motion and fibrosis | Availability, artefact and device/renal considerations |
| ECG/Holter | Electrical phenotype and arrhythmia burden | May be intermittent or non-specific |
| Genetics | Aetiology and cascade testing | Variants require expert classification and counselling |
Criteria and differential diagnosis
The 2020 Padua criteria broadened assessment beyond classic right-dominant disease and incorporated CMR tissue criteria. The 2024 European Task Force criteria further address clinical diagnosis and phenotype. Apply the chosen framework explicitly and avoid mixing thresholds from different systems without explanation.
Important mimics include athlete’s heart, myocarditis, cardiac sarcoidosis, dilated cardiomyopathy, congenital shunts, pulmonary hypertension and idiopathic RV outflow-tract arrhythmia. Coronary disease should be considered for LV-predominant abnormalities.
Management implications
Management belongs in an inherited-cardiac-condition and electrophysiology pathway. It includes arrhythmic risk assessment, exercise counselling, family screening, genotype interpretation and consideration of an implantable cardioverter-defibrillator. Imaging severity alone should not determine sudden-death prevention.
Selected references
- International criteria for diagnosis of arrhythmogenic cardiomyopathy: the Padua criteria.
- 2024 European Task Force criteria for clinical diagnosis of arrhythmogenic cardiomyopathy.
- 2023 ESC cardiomyopathy guideline.
Educational material only. Suspected ACM requires specialist assessment, genetic counselling where appropriate and individualised arrhythmic-risk evaluation.
The Cardiac Compass 