Prolonged PR interval

An ECG finding in which the PR interval exceeds 200 ms, indicating delayed conduction of electrical impulses from the atria to the ventricles, most commonly through the atrioventricular (AV) node.

Causes

• Medication affecting AV nodal conduction

  • β-blockers

  • Calcium channel blockers (verapamil and diltiazem)

  • Digitalis/digoxin

  • Amiodarone

• Physiological causes

  • Trained athletes with increased vagal tone and low resting heart rate

  • Sleep-related increased parasympathetic activity

• Age-related degenerative fibrosis of the cardiac conduction system

• Cardiac structural and ischemic causes

  • Ischemic heart disease

  • Myocardial infarction

  • Cardiomyopathy

  • Congenital structural heart defects affecting the AV node or conduction pathways

  • Post-cardiac surgery conduction abnormalities

• Inflammatory and infectious diseases affecting cardiac conduction tissue

  • Lyme disease

  • Myocarditis

  • Rheumatic fever

  • Endocarditis

• Metabolic and endocrine abnormalities affecting myocardial conduction

  • Hyperkalemia

  • Hypothyroidism

  • Acid–base disturbances

• Infiltrative and systemic causes

  • Sarcoidosis

  • Cardiac amyloidosis

  • Other infiltrative cardiomyopathies

• Genetic: SCN5A mutations affecting cardiac sodium channels