Prolonged PR interval

An ECG finding in which the PR interval exceeds 200 ms, indicating delayed atrioventricular conduction (most often at the AV node), and corresponding classically to first-degree atrioventricular block. Possible causes are medications (β-blocker, calcium blocker, digitalis/digoxin, amiodarone), trained athletes with naturally low resting heart rate, aging (degenerative changes), sleep (increased vagal tone), heart disease (ischemic heart disease, cardiomyopathy, congenital structural heart defects that impact the AV node), inflammation (Lyme disease, myocarditis, rheumatic fever, endocarditis), metabolic imbalance (hyperkalemia, hypothyroidism, acid-base disturbances), sarcoidosis, amyloidosis, and genetic mutations (SCN5A).