Treatment of Atrioventricular (AV) Block

Classification and Diagnosis

AV block is classified as first-, second-, or third-degree (complete) block, with first-degree AV block characterized by a PR interval >0.20 seconds, according to the American Heart Association 2
Second-degree AV block is further divided into Type I (Wenckebach) and Type II, with Type I characterized by progressive PR prolongation before a nonconducted beat, and Type II characterized by fixed PR intervals before and after blocked beats, usually with wide QRS, as defined by the American College of Cardiology 2
Advanced second-degree AV block is characterized by the blocking of 2+ consecutive P waves with some conducted beats, and third-degree AV block is characterized by the complete absence of AV conduction, as stated by the American Heart Association 2

Permanent pacemaker implantation is indicated for symptomatic third-degree and advanced second-degree AV block, including cases with bradycardia, ventricular arrhythmias, and medical conditions requiring drug therapy that causes symptomatic bradycardia, according to the American College of Cardiology 1, 3, 5
Permanent pacemaker implantation is also recommended for patients with asystole ≥3.0 seconds or escape rate <40 bpm in awake, symptom-free patients, and for patients with atrial fibrillation and bradycardia with pauses ≥5 seconds, as stated by the American Heart Association 2, 5

No specific treatment is required for asymptomatic patients with isolated first-degree AV block, but marked first-degree AV block (PR interval ≥300 ms) with symptoms may require permanent pacing, according to the American College of Cardiology 2, 4
Permanent pacing may also be considered for patients with neuromuscular diseases and any degree of AV block due to unpredictable progression, as recommended by the American Heart Association 3

Reversible causes of AV block, such as electrolyte abnormalities, Lyme disease, hypervagotonia, perioperative hypothermia, and inflammation near the AV conduction system after surgery, should be corrected first, according to the American College of Cardiology 2, 3
Permanent pacing may be necessary despite transient resolution in patients with sarcoidosis, amyloidosis, neuromuscular diseases, and post-valve surgery, as stated by the American Heart Association 2, 3

Avoid certain medications in pre-excited atrial fibrillation, such as intravenous digoxin, amiodarone, beta blockers, diltiazem, and verapamil, as they may enhance conduction over accessory pathways, according to the American College of Cardiology 6

Regular follow-up is essential for patients with first-degree AV block with concurrent bundle branch block, as they require closer monitoring, according to the American Heart Association 4