Two cases of wide QRS complex tachycardia caused by anamorelin.

Anamorelin is prescribed for cancer cachexia treatment. Anamorelin is a ghrelin receptor antagonist and exerts a sodium channel blockade effect, possibly inducing disorders of the cardiac conduction system. We herein report two cases of wide QRS complex tachycardia caused by anamorelin. In both cases, the patients had liver dysfunction. Anamorelin is mainly metabolized in the liver; hence, sodium channel blockade by anamorelin during liver dysfunction can cause serious side effects, including wide QRS complex tachycardia, similar to flecainide toxicity. The differential diagnosis of wide QRS tachycardia caused by anamorelin can be challenging because conventional electrocardiogram criteria cannot be applicable in patients with drug intoxication. It can worsen the situation for the use of antiarrhythmic drugs for wide QRS tachycardia. The appropriate treatment is supportive care until anamorelin is metabolized. To our best knowledge, this is the first study to report the life-threatening adverse effects of anamorelin. Learning objective: Anamorelin is prescribed for cancer cachexia treatment. Anamorelin can cause wide QRS complex tachycardia. Our findings in the two cases we encountered indicate that we should be aware of wide QRS complex tachycardia in patients taking anamorelin, especially if they have liver dysfunction. We should suspect the condition to be the adverse effect of anamorelin and monitor the electrocardiogram and blood test findings regularly to prevent this fatal side effect.