Management of patients with drug-induced atrioventricular block

Objective: To identify the frequency of atrioventricular (AV) conduction improvement after discontinuation of the culprit drug in patients with AV block.

Background: AV blockers are considered as reversible causes of AV block that do not require pacemaker (PM) implantation. However, controversial reports declared that a major part of these drug-induced AV blocks are persistent or recurrent.

Methods: Of 668 consecutive patients with symptomatic type II second- or third-degree AV block, 2:1 AV block, atrial fibrillation, and bradyarrhythmia, 108 patients (62 patients enrolled prospectively) using AV blockers without myocardial infarction, electrolyte abnormalities, digitalis toxicity, and vasovagal syncope were enrolled into the present study. The level of AV block (AV-nodal or infranodal) was defined according to electrocardiographic characteristics.

Results: The most frequent culprit medications were β-blockers followed by digoxin. Drug discontinuation was followed by resolution of AV block in 72% of cases, whereas spontaneous resolution of AV block occurred in only 6.6% of patients who had AV block in the absence of medications. However, 27% of patients with improved AV conduction experienced a recurrence of AV block despite discontinuation of the culprit drug. Twenty-one of 24 carvedilol-induced AV blocks resolved after discontinuation of the drug and never recurred, whereas 24 of 36 metoprolol-induced AV blocks persisted or recurred. A digoxin-induced AV block usually improved (28 of 39) after withdrawal of the drug. Roughly half of the patients with drug-induced AV block underwent permanent PM implantation.

Conclusion: Drug-induced AV block is a serious disease that requires a permanent PM for almost half of the patients.