To the Editor:

A 64-year-old female undergoing abdominal surgery developed transient third-degree atrio-ventricular block (IIIAVB) after a dose of sugammadex. She had no noteworthy abnormalities on the ECG (ESM Fig. 1A) or of the serum electrolytes and no history of allergy or sugammadex usage. After the epidural catheter was inserted, general anesthesia was induced with propofol, fentanyl, and rocuronium, and maintained with desflurane, remifentanil, and rocuronium. Her hemodynamics remained stable (the operation time 559 min, bleeding 709 ml). When she regained consciousness, sugammadex was administered. Then IIIAVB was developed 4 min after 200 mg sugammadex administration (ESM Fig. 1B). The ECG converted to a wide QRS pattern after 0.5 mg of atropine, and 0.1 mg of epinephrine administration, to sinus rhythm within few minutes (ESM Fig. 1C, D). The examination about her ECG was uneventful after surgery.

Anaphylaxis has been reported as an adverse reaction to sugammadex [1]. Animal study and several clinical reports suggest that allergic reactions are the possible cause of AVB [2, 3]. Considering the allergic reaction to sugammadex, we should have checked plasma level of histamine and tryptase.