Table 2.

The ‘Padua criteria’ for diagnosis of ACM

Category	Right ventricle (upgraded 2010 ITF diagnostic criteria)	Left ventricle (new diagnostic criteria)
I. Morpho‐functional ventricular abnormalities	By echocardiography, CMR or angiography:	By echocardiography, CMR or angiography: Minor
	► Major
specific	• Regional RV akinesia, dyskinesia, or bulging plus one of the following:	► • Global LV systolic dysfunction (depression of LV EF or reduction of echocardiographic global longitudinal strain), with or without LV dilatation (increase of LV EDV according to the imaging test nomograms for age, sex, and BSA)
	‐ Global RV dilatation (increase of RV EDV according to the imaging test specific nomograms)
	‐ Global RV systolic dysfunction (reduction of RV EF according to the imaging test specific nomograms)	Minor
		• Regional LV hypokinesia or akinesia of LV free wall, septum, or both
II. Structural myocardial abnormalities	Minor
	• Regional RV akinesia, dyskinesia or aneurysm of RV free wall
	By CE‐CMR:Major	By CE‐CMR:Major
	• Transmural LGE (stria pattern) of ≥1 RV region(s) (inlet, outlet, and apex in 2 orthogonal views) By EMB (limited indications): Major	► • LV LGE (stria pattern) of ≥1 Bull's Eye segment(s) (in 2 orthogonal views) of the free wall (subepicardial or midmyocardial), septum or both (excluding septal junctional LGE)
	• Fibrous replacement of the myocardium in ≥1 sample, with or without fatty tissue
III. Repolarization abnormalities	Major	Minor
	► • Inverted T waves in right precordial leads (V1, V2 and V3) or beyond in individuals with complete pubertal development (in the absence of complete RBBB)
	Minor
	• Inverted T waves in leads V1 and V2 in individuals with completed pubertal development (in the absence of complete RBBB) • Inverted T waves in V1, V2, V3 and V4 in individuals with completed pubertal development in the presence of complete RBBB.	► • Inverted T waves in left precordial leads (V4–V6) (in the absence of complete LBBB)
IV. Depolarization abnormalities	Minor	Minor
	► • Epsilon wave (reproducible low‐amplitude signals between end of QRS complex to onset of the T wave) in the right precordial leads (V1 to V3) ► •Terminal activation duration of QRS ≥ 55 ms measured from the nadir of the S wave to the end of the QRS, including R′, in V1, V2 or V3 (in the absence of complete RBBB)	• Low QRS voltages (<0.5 mV peak to peak) in limb leads (in the absence of obesity, emphysema, or pericardial effusion)
V. Ventricular arrhythmias	Major	Minor
	• Frequent ventricular extrasystoles (>500 per 24 h), non‐sustained or sustained ventricular tachycardia of LBBB morphology	•Frequent ventricular extrasystoles (>500 per 24 h), non‐sustained or sustained ventricular tachycardia with a RBBB morphology (excluding the ‘fascicular pattern’)
	Minor
	• Frequent ventricular extrasystoles (500 per 24 h), non‐sustained or sustained ventricular tachycardia of LBBB morphology with inferior axis (‘RVOT pattern’)
VI. Family history/genetics	Major
	• ACM confirmed in a first‐degree relative who meets diagnostic criteria • ACM confirmed pathologically at autopsy or surgery in a first degree relative • Identification of a pathogenic or likely pathogenetic ACM mutation in the patient under evaluation
	Minor
	•History of ACM in a first‐degree relative in whom it is not possible or practical to determine whether the family member meets diagnostic criteria •Premature sudden death (<35 years of age) due to suspected ACM in a first‐degree relative •ACM confirmed pathologically or by diagnostic criteria in a second‐degree relative

Note: Adapted from References 7, 10 with minor modifications. Any diagnosis of ‘right‐dominant’ or biventricular ACM requires that at least 1 criterion (RV criterion for ‘right‐dominant’ both RV and LV criterion for biventricular ACM), either major or minor from category I (Morpho‐functional ventricular abnormalities) or II (Structural myocardial abnormalities) be fulfilled. ‘Right‐dominant ‘ACM definite diagnosis: 2 major, or 1 major and 2 minor, or 4 minor RV criteria, borderline diagnosis: 1 major and 2 minor, or 3 minor RV criteria, possible diagnosis: 2 minor RV criteria,. Biventricular ACM definite diagnosis: 2 major, or 1 major and 2 minor, or 4 minor RV or LV criteria, borderline diagnosis: 1 major and 2 minor, or 3 minor RV or LV criteria, possible diagnosis: 2 minor RV or LV criteria. ‘Left‐dominant’ ACM diagnosis: a major structural LV criterion plus pathogenic or likely pathogenic ACM‐causing gene mutation must be present. ► criteria, that were present in our patient.

Abbreviations: ACM, arrhythmogenic cardiomyopathy; BSA, body surface area; EDV, end diastolic volume; EF, ejection fraction; ITF=International Task Force; LBBB, left bundle‐branch block; LGE, late gadolinium enhancement; LV, left ventricle; RBBB, right bundle‐branch block; RV, right ventricle; RVOT, right ventricular outflow tract.