Shortened QT interval

A pathologically reduced QT or QTc interval on ECG, reflecting abnormally brief ventricular repolarization and potentially increasing the risk of atrial and ventricular arrhythmias.

• Mild QTc shortening: <350–360 ms

• Severe shortening: <330 ms

Causes

• Electrolyte and metabolic causes

  • Hypercalcemia

  • Hyperkalemia

  • Acidosis

  • Hyperthermia

• Medication-related causes

  • Digoxin

  • Testosterone

• Genetic causes

  • Short QT syndrome

  • Ion channel mutations affecting cardiac repolarization

• Physiological causes

  • High vagal/parasympathetic tone

  • Increased sympathetic activity

  • Elevated catecholamine states (stress hormones)