Shortened QT interval

A pathologically reduced QT or QTc interval on ECG (mild QTc shortening: <350-360 ms, severe shortening: <330 ms), reflecting abnormally brief ventricular repolarization and potentially associated with increased risk of atrial and ventricular arrhythmias. Possible causes are hypercalcemia, hyperkalemia, acidosis, hyperthermia, medications (digoxin, testosterone), genetic disease (short QT syndrome, ion channel mutations), and physiologic factors (high vagal/parasympathetic tone or elevated stress hormones such as catecholamines).