To the Editor:
We have read with great interest the issues raised by Ramón Fité-Mora and thank him for his timely clarifications. We would like to offer some comments regarding his letter and our article.1 The yellow card sent from our center to the Spanish Pharmacovigilance System (Sistema Español de Farmacovigilancia) described all the drugs that the patient took at the time of arrhythmia onset, among them sertraline and rupatadine. The purpose of this card is to report a suspected adverse drug reaction.2 We consider it appropriate to report this possible adverse effect, due to the recent marketing of this drug in Spain and the relevance of the clinical event.
We would like to emphasize the temporal relationship between the time of rupatadine administration and symptom onset. The patient had already been receiving treatment with sertraline for several months without arrhythmic problems being recorded, even with previous electrocardiograms indicating a prolonged QT interval. Indeed, as we mentioned in the original article, the patient had been examined by the neurology service for previous syncopal symptoms, without a conclusive and definitive diagnosis. However, after starting rupatadine, the diagnosis was clear, since the patient presented presyncopal symptoms with 2 episodes of syncope, one of them in which ventricular tachycardia was recorded. We consider that a previous syncopal episode cannot be compared to the definitive diagnosis of the case. Again, the temporal relationship between the suspension of both drugs was the factor that normalized the QT interval and led to the disappearance of the ventricular arrhythmia.
As described, the patient presented a prolonged QT interval on previous electrocardiograms, so we emphasize that the final diagnosis was aborted sudden death due to torsade de pointes secondary to idiopathic long QT syndrome and exacerbated by rupatadine treatment. We agree that it would have been better to have made the combined administration of rupatadine and sertraline more explicit.
Finally, we do not consider that rupatadine was the cause of arrhythmia onset, rather, given a long QT syndrome substrate, a long list of factors can induce torsade de pointes, among which is recently initiated medication.3,4 Thus, the association, rather than a causal link, between rupatadine and the symptoms is clear, although other influencing factors also exist.