A 72-year-old man is found to have an ECG showing a PR interval of 0.28 sec with consistent 1:1 AV conduction. No dropped beats occur. He is asymptomatic. What is the diagnosis and appropriate management?
- A Second-degree AV block Mobitz type I; admit for monitoring
- B First-degree AV block; reassure and no specific treatment required ✓
- C Second-degree AV block Mobitz type II; implant pacemaker
- D Third-degree AV block; temporary pacing
Correct answer: B. First-degree AV block; reassure and no specific treatment required
Explanation
First-degree AV block is defined as PR interval > 200 ms (0.20 sec) with 1:1 AV conduction and no dropped beats. It is benign, requires no treatment in asymptomatic individuals, and is not a form of AV block in the pathologic sense. Common causes include increased vagal tone, inferior ischemia, electrolyte disturbances, and drugs (digoxin, beta-blockers, calcium channel blockers). Second-degree blocks involve intermittent non-conduction; third-degree block is complete AV dissociation.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
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Written and medically reviewed by the StethoPrep medical team.