Gemcitabine-induced atrial fibrillation: A hitherto unreported manifestation of drug toxicity

Background: Gemcitabine is an antimetabolic drug for solid tumors. Altough its pharmacokinetics as well as its side-effects are well known, paroxysmal atrial fibrillation associated to the administration of this drug has not yet been described. Patients and methods: We describe the case of a 78-year-old man with pancre atic adenocarcinoma who presented repeated paroxysmal atrial fibrillation e pisodes 18-24 hours after every gemcitabine infusion which resolved with an tiarrhythmic drugs. This clinical history was positive for a remote brief e pisode of atrial fibrillation, which resolved spontaneously, and the patien t had no predisposing factors for supraventricular arrhythmias (systemic hy pertension, diabetes or coronary artery disease). Results: Cardiac work-up revealed only a mild mitral-valve prolapse and com plete right bundle branch block. During the arrhythmia episodes no other pr ecipitating factors were reported. The close temporal relationship of the a rrhythmia to drug administration and the recurrence of arrhythmia upon rech allenge allowed to hypothesize an intrinsic pro-arrhythmic effect of gemcit abine or its metabolite 2',2'-difluorodeoxyuridine. Conclusions: The occurrence of atrial fibrillation during the administratio n of gemcitabine may be considered as a cardiac arrhythmia drug-related tox icity. This side-effect of gemcitabine infusion is a previously unreported sign of drug toxicity; therefore, a high level of awareness to this problem is warranted when this drug is administered.