All-trans retinoic acid-induced, life-threatening complete atrioventricular block.

We report a case of complete atrioventricular block (CAVB) with ventricular asystole and recurrent AVBs due to all-trans retinoic acid (ATRA). A 57-year-old man with acute promyelocytic leukemia was undergoing induction therapy with ATRA and developed episodic seizures with altered consciousness on the 14(th) day and then CAVB followed by cardiac arrest on the 15(th) day. Although he initially recovered after resuscitation, he suffered from recurrent CAVB, which persisted for 3 days despite immediate ATRA discontinuation. He then received ATRA retreatment with reduction of dosage, but a high-degree AVB recurred on the 5(th) day. After discontinuation of ATRA therapy, the patient recovered 3 days later without any cardiovascular event during follow-up. The serial electrocardiogram changes suggested an infra-Hisian block with possible ATRA dose-response relationship. To our knowledge, this is the first established case of ATRA-induced CAVB in the literature. We suggest clinical alertness for this life-threatening complication.