Drug-induced atrioventricular block: prognosis after discontinuation of the culprit drug.
OBJECTIVE
The goal of this study was to determine how often atrioventricular (AV) block is really caused by medications.


BACKGROUND
Beta-blockers, verapamil, and diltiazem are considered a cause of AV block for which pacemaker implantation is not indicated. However, it is not known if such patients can expect a benign course after discontinuation of the culprit medication.


METHODS
Consecutive patients with II or III degree AV block not related to acute myocardial infarction, digitalis toxicity, or vasovagal syncope were studied. The level of AV block (AV-nodal or infranodal) was defined by electrocardiographic criteria. The cause and effect relation between AV block and drugs was defined according to the response to drug discontinuation.


RESULTS
Of 169 patients with AV block, 92 (54%) were receiving beta-blockers and/or verapamil or diltiazem. Patients receiving medications had similar clinical and electrocardiographic characteristics with patients who had AV block in the absence of drugs. Drug discontinuation was followed by resolution of AV block in 41% of cases, whereas spontaneous improvement of AV conduction occurred in 23% of patients who had AV block in the absence of drugs. However, 56% of the patients for whom drug discontinuation led to resolution of AV block had recurrence of AV block in the absence of therapy. Atrioventricular block that was "truly caused by drugs" was found in only 15% of patients who had II or III degree AV block during therapy with beta-blockers, verapamil, or diltiazem.


CONCLUSIONS
Atrioventricular block is commonly "related to drugs" but is rarely "caused by drugs."
Zeltser
David
D
Internal Medicine D, Tel Aviv-Sourasky Medical Center and Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel.
Justo
Dan
D
Halkin
Amir
A
Rosso
Raphael
R
Ish-Shalom
Maya
M
Hochenberg
Mordechai
M
Viskin
Sami
S
D000319:Adrenergic beta-Antagonists / Q000009:adverse effects; D000368:Aged; D000369:Aged, 80 and over; D002121:Calcium Channel Blockers / Q000009:adverse effects; D004110:Diltiazem / Q000009:adverse effects; D004562:Electrocardiography; D005260:Female; D005500:Follow-Up Studies; D006327:Heart Block / Q000139:chemically induced* / Q000503:physiopathology; D006801:Humans; D006973:Hypertension / Q000188:drug therapy; D007557:Israel; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D017211:Treatment Failure; D014700:Verapamil / Q000009:adverse effects
D000319:Adrenergic beta-Antagonists; D002121:Calcium Channel Blockers; D014700:Verapamil; D004110:Diltiazem