PR depression

A downward displacement of the PR segment below the TP baseline on surface ECG, reflecting abnormal atrial electrical activity and altered atrial repolarization.

Causes

• Inflammatory and infectious cardiac causes

  • Acute pericarditis

  • Myocarditis

  • Pericardial effusion

  • Myopericarditis

• Ischemic and structural cardiac causes

  • Atrial ischemia

  • Left atrial overload

  • Left atrial enlargement due to increased left atrial pressure:

    • Left ventricular failure

    • Mitral valve disease

• Medications affecting atrial electrophysiology

  • Digoxin

  • Adrenaline (epinephrine)

• Normal variant PR-segment changes (rare)