Arrhythmogenic cardiomyopathy
Task Force RV criteria measured correctly, regional wall motion, and when to send for CMR.
Numbers to remember
- Major: regional akinesia/dyskinesia/aneurysm plus PLAX RVOT ≥32 mm (≥19 mm/m²), PSAX RVOT ≥36 mm (≥21 mm/m²) or FAC ≤33% [145]
- Minor: regional akinesia/dyskinesia plus PLAX RVOT 29–<32 mm, PSAX RVOT 32–<36 mm or FAC 34–40% [145]
- Size alone is never a criterion — a regional wall-motion abnormality is mandatory [145]
Questions echo must answer
Arrhythmogenic cardiomyopathy replaces myocardium with fibrofatty tissue. The disease is classically right-ventricular (ARVC) but increasingly biventricular or left-dominant [14,146]. The echocardiographic Task Force criteria require a regional wall-motion abnormality combined with RV dilatation or dysfunction [145]. The Padua criteria add LV involvement and CMR tissue characterisation [146].
- Regional RV wall motionLook for akinesia, dyskinesia or micro-aneurysms of the RV free wall, RVOT and subtricuspid region (the "triangle of dysplasia").
- SizeRVOT in PLAX and PSAX, measured as the Task Force defines [145].
- FunctionFAC, TAPSE, S′ and RV free-wall strain [3,163].
- LV involvementLook for inferolateral hypokinesia and reduced GLS [146].
- Alternative explanationsExclude shunts, PH, athlete's heart and sarcoidosis.
Acquisition protocol
- PLAXRVOT diameter from the anterior RV wall to the interventricular septum–aortic junction, at end-diastole [145].
- PSAX-AVProximal RVOT diameter at end-diastole [145].
- RV-focused A4CRVD1–3 and FAC by tracing the endocardium with the trabeculations included in the cavity. Calculate TAPSE, S′ and RV free-wall strain (and dispersion if available) [3,163].
- RV inflow and subcostalLook at the inferior (subtricuspid) and anterior RV walls for aneurysms. These are often seen only here.
- ContrastUse contrast if the RV free wall is poorly seen.
- LVLVEF, GLS and regional motion (inferolateral).
- ExcludeColour across the IAS (shunt), pulmonary vein drainage, TR velocity (PH).
- RVOT PLAX (mm and mm/m²)
- RVOT PSAX (mm and mm/m²)
- FAC
- Regional RV wall motion: RVOT / free wall / subtricuspid
- TAPSE, S′, RV strain
- LV involvement
- Shunt and PH excluded
Diagnosis & severity
2010 Task Force criteria — echocardiographic imaging [145]
| Grade | Regional wall motion | AND one of |
|---|---|---|
| Major | RV akinesia, dyskinesia or aneurysm | PLAX RVOT ≥32 mm (≥19 mm/m²); PSAX RVOT ≥36 mm (≥21 mm/m²); FAC ≤33% |
| Minor | RV akinesia or dyskinesia | PLAX RVOT ≥29 to <32 mm (≥16 to <19 mm/m²); PSAX RVOT ≥32 to <36 mm (≥18 to <21 mm/m²); FAC >33% to ≤40% |
A definite diagnosis needs 2 major, or 1 major plus 2 minor, or 4 minor criteria from different categories (imaging, tissue, repolarisation, depolarisation, arrhythmia, family history) [145].
NoteThe Padua criteria (2020) keep the RV criteria and add CMR LGE and LV criteria, for biventricular and left-dominant forms [146].
Thresholds that change management
- Any suggestive echo, or unexplained VT of RV origin (LBBB morphology) → cardiac MRI with LGE, a signal-averaged or high-resolution ECG, Holter and genetic testing [14,38,146].
- ICD decisions (VT, syncope, severe RV or LV dysfunction) follow the ESC ventricular-arrhythmia and cardiomyopathy guidelines. Echo supplies RV and LV function and size [14,38].
- Stop competitive and high-intensity endurance sport in a definite diagnosis, because exercise accelerates the disease [14,150].
- Family screening: echo and ECG in first-degree relatives, repeated over years because penetrance is age-dependent [14].
Pitfalls & mimics
PitfallAn oblique PLAX cut inflates the RVOT. Measure exactly as defined at end-diastole, and index to BSA. Athletes often exceed the size thresholds without any regional abnormality [145,150].
- The moderator band and trabeculations create apparent "bulges". Confirm dyskinesia in two views.
- Athlete's heart: symmetric RV and LV enlargement, normal regional motion and normal or supranormal function [150].
- Volume-overload RV (ASD, anomalous pulmonary venous return, TR) and PH (D-shaped septum, high TR velocity).
- Cardiac sarcoidosis can mimic ARVC. Look for basal septal thinning and conduction disease.
- Normal echo does not exclude ACM. Early disease is electrical before it is structural. CMR is more sensitive [146].