Comprehensive non-invasive assessment of electrocardiographic abnormalities and cardiac arrhythmias in patients with genetically confirmed mitochondrial diseases

•Novel Tp-e and Tp-e/QT indicate ventricular repolarization and dispersion disturbances in mitochondrial disease (MitD).•Atrio- and intraventricular conduction disturbances in MitD are frequently observed.•Ventricular arrhythmias in MitD are observed relatively rarely.•mtDNA mutation promotes for conduction disturbances and ventricular arrhythmias.