Surdosage en digoxine : lorsqu'une inefficacité du traitement antidotique remet en cause le diagnostic…

Digoxin is still used in the treatment of atrial fibrillation and heart failure. This medication can cause severe poisoning in older people regarding their comorbidities. We report the case of an 83 years old patient, with renal insufficiency, suffering from digoxine poisoning and presenting vomiting, abdominal pain and bradycardia. Electrocardiographic recordings showed signs of digitalis impregnation. Digoxin was measured at 6.6 ng/mL. During the treatment, the antidote (Fab IG antidigitalis) was administered twice which allowed an improvement in gastrointestinal symptoms but had no effect on cardiovascular ones. Even if an electrographic improvement was present, the patient presented persistent bradycardia associated with hypotensive phases. The patient's interrogation revealed that he was also taking a beta-blocker, bisoprolol. Because of its renal failure, we assumed that patient presented likely a co-poisoning with beta-blocker, but this could not be confirmed by a plasma or urinary dosage of this medication. Thus, the serotherapy antagonized specifically digoxin but not bisoprolol which could explain the persistence of bradycardia and hypotensive phases. After a hospital surveillance for 6 days, the patient was able to return home. In conclusion, this observation does not question the therapeutic indication of antidigitalis antibodies, but in case of their apparent ineffectiveness during digitalis intoxication, another toxic etiology must be sought.