• gender (female/male), and age in years;
• family history for sudden cardiac death;
• previous documentation of supraventricular and/or ventricular arrhythmias (VAs);
• previous secondary prevention ICD implantation, previous transcatheter ablation of VAs;
• symptoms (history of unexplained syncope/pre-syncope, palpitations, dyspnea, chest pain);
• signs (mid-systolic click, murmurs of mitral regurgitation);
• use of anti-arrhythmic drugs and/or beta-blockers.

• left atrial biplane volume in mL/m2;
• presence, localization, and end-systolic measurement in millimeters of mitral annular disjunction (MAD);
• mitral leaflet thickness in millimeters, presence of bileaflet prolapse;
• mitral regurgitation (MR) grade, quantified by integrating qualitative and quantitative criteria according to the European guidelines;
• left ventricular (LV) diameters in millimeters, volumes in mL/m2, and ejection fraction in %;
• presence of curling of the posterolateral LV wall;
• presence of the Pickelhaube sign at tissue Doppler imaging;
• right ventricular end-diastolic area in cm2/m2, TAPSE in millimeters, and fractional area change in %;
• systolic pulmonary artery pressure in mmHg, derived from the peak velocity of the tricuspid regurgitation and from the estimated right atrial pressure.

• baseline rhythm (sinus rhythm, atrial fibrillation/flutter, junctional rhythm);
• PQ and QRS intervals in milliseconds;
• T wave inversion or biphasic T waves in the inferior and lateral leads;
• QTc interval in milliseconds;
• occurrence of premature supraventricular complexes;
• occurrence of premature ventricular complexes (PVCs).

• baseline rhythm (sinus rhythm, atrial fibrillation/flutter, junctional rhythm);
• frequency (expressed in absolute number and as percentage of total beats number), and repetitiveness of premature supraventricular complexes;
• occurrence of atrial fibrillation;
• frequency (expressed in absolute number and as percentage of total beats number), and repetitiveness of PVCs.

Ventricular arrhythmias (VAs) will be classified as suggested in the recently published EHRA consensus statement:

• MILD VAs, defined as ≥ 5% total PVC burden or non-sustained (< 30 seconds) ventricular tachycardia (VT) runs with a heart rate < 120 bpm
• MODERATE VAs, defined as non-sustained (< 30 seconds) VT runs with a heart rate of 120-179 bpm
• SEVERE VAs, defined as non-sustained (< 30 seconds) VT runs with a heart rate > 180 bpm or sustained (≥ 30 seconds) VT/ventricular fibrillation.

• MR grade (based on the regurgitant volume and regurgitant fraction);
• LV mass in g/m2;
• biventricular volumes in mL/m2, stroke volumes in mL, and ejection fraction in %;
• presence of curling of the posterolateral LV wall;
• presence, localization, end-systolic and end-diastolic measurement in millimeters of MAD;
• presence and distribution of LGE.