2.1 Study design and Patient selection
We performed a retrospective study of consecutive patients admitted to the emergency department of a tertiary hospital between the 28th of January and 17th of March 2020. Only patients with an electrocardiogram (ECG) were included. Exclusion criteria were normal corrected QT interval (cQT) (lower than 470ms in men and 480ms in women as defined by the American Society of Cardiology), repeated ECGs following ER admissions, bad electrocardiographic quality, congenital LQTS, atrial fibrillation (AF)/arrhythmias and pacemaker rhythm.