Clinical Significance and Management of Atrioventricular Block Associated With Bradycardic/Antiarrhythmic Drug Therapy: Drug-Induced or Drug-Revealed?

Abstract

The development of advanced atrioventricular block (AVB) in patients on bradycardic and/or antiarrhythmic therapy (drug-related AVB) represents a clinical challenge, raising the question of whether the AVB is directly caused by these agents (drug-induced AVB) or if the offending drugs exacerbate an underlying conduction system disease. Traditionally, β-blockers, non-dihydropyridine calcium channel blockers, class Ic/III antiarrhythmics, and digoxin have been considered reversible causes of advanced AVB. However, recent evidence shows a weak cause-and-effect relationship between these drugs and AVB in the elderly, along with high recurrence rates of AVB despite initial resolution after drug discontinuation. This may also apply to patients on high doses of these medications, drug combinations, or with additional reversible factors such as hyperkalemia. Despite these considerations, the European Guidelines do not suggest permanent pacing for AVB due to transient causes that are correctable, including bradycardic/antiarrhythmic drug therapy. On the other hand, the American Guidelines recommend permanent pacing for selected patients with symptomatic second- or third-degree AVB who are on stable, necessary antiarrhythmic or β-blocker treatment, without waiting for drug washout or reversibility. Notably, an accumulating body of evidence indicates that true drug-induced AVB is rare, while recurrence rates are high. Therefore, early permanent pacing should be recommended, especially for frail elderly patients. Moreover, in patients with drug-related AVB and atrial tachyarrhythmias, adopting an early permanent pacing approach seems prudent when bradycardic and/or antiarrhythmic treatment is necessary. Finally, delays in permanent pacing are not justified when temporary pacing is needed, given the increased associated risks in such cases.