The CMR criteria are functional: regional RV akinesia, dyskinesia or dyssynchronous contraction PLUS RV dilatation or dysfunction. Fat on its own is not a criterion; LV subepicardial LGE identifies left-dominant disease.
Orient first
- Arrhythmogenic cardiomyopathy replaces myocardium with fibro-fatty tissue; the RV free wall, outflow tract and inferior wall (the "triangle of dysplasia") are typical.
- Task Force (2010) and Padua (2020) criteria use CMR regional wall motion WITH volumes — major criteria need both; thresholds are indexed to BSA and sex (verify the current values).
- Left-dominant and biventricular forms show subepicardial/mid-wall LV LGE, often inferolateral, which can mimic myocarditis.
Acquire the study
- Cine SSFP short-axis stack covering the entire RV plus axial (transaxial) cine stack and RVOT view; LGE including RV free wall; black-blood T1 optional for fat (low value).
The manoeuvre
- Axial and RVOT cine: regional RV akinesia, dyskinesia or bulging (micro-aneurysms), and dyssynchronous contraction — describe the segment.
- Short-axis stack: RV end-diastolic volume index and RVEF against sex-specific criteria; LV volumes and EF.
- LGE: RV free wall and RVOT (difficult — thin wall); LV subepicardial/mid-wall inferolateral LGE for left-dominant disease.
- State which Task Force/Padua imaging criteria are MET or NOT MET, and that diagnosis integrates ECG, arrhythmia, family and genetic criteria.
What confirms it
- Regional RV wall-motion abnormality together with RV dilatation or dysfunction meeting a major imaging criterion — within the full criteria set.
What licenses you to exclude it
- Normal RV volumes, function and regional motion on a complete axial and short-axis stack argue against RV-predominant disease; they do not exclude the left-dominant form — look at LV LGE.
The classic misread
- Diagnosing ARVC from intramyocardial fat — common in normal older hearts.
- Calling the normal moderator-band insertion or the RV apex "focal dyskinesia".