Effet de la prise d’antipsychotiques atypiques sur l’intervalle QT des patients du Centre de pédopsychiatrie du Centre hospitalier universitaire de Québec

Resume Objectifs : Decrire les variations de l’intervalle QTc et le suivi effectue aupres des patients du Centre de pedopsychiatrie du Centre hospitalier universitaire de Quebec recevant des antipsychotiques atypiques. Methodologie : Etude descriptive retrospective longitudinale realisee au moyen de la revue de 166 dossiers medicaux de patients âges de 18 ans au maximum, hospitalises ou frequentant l’hopital de jour du Centre de pedopsychiatrie du Centre hospitalier universitaire de Quebec et ayant recu un antipsychotique atypique entre le 1er janvier 2007 et le 31 decembre 2009. Resultats : On a mesure en tout 236 QTc, ce qui represente 40 sujets inclus dans l’etude. La moyenne des QTc obtenue en monotherapie est de 417 ± 26 msec. Au total, 11 % des QTc ont ete consideres anormaux en termes de valeur absolue et 1 % en termes de difference par rapport a la valeur initiale. Une dose elevee  d’olanzapine  (p  =  0,001)  et de  quetiapine (p = 0,0036) ainsi que la presence d’une interaction pharmacodynamique (p = 0,028) ont ete associees de facon statistiquement significative a une augmentation du risque de prolongation de l’intervalle QTc. Conclusion : La prolongation de l’intervalle QTc a ete observee dans une faible proportion d’ECG mesures sur des enfants recevant des antipsychotiques atypiques. Notre etude a permis de determiner cer- taines associations liees a un risque de prolongation de l’intervalle QTc, telles qu’une dose elevee d’un antipsychotique, une polytherapie ainsi que la presence d’interactions medicamenteuses. Mots-cles : antipsychotique atypique, intervalle QT, torsades de pointes, electrocardiogramme, pediatrie Abstract Objective: To describe the observed variations in QTc interval and the follow-up that was done for child psychiatry patients of the Centre hospitalier universitaire de Quebec receiving atypical antipsychotics. Methods: The study had a retrospective and lon- gitudinal descriptive design and was done by re- viewing 166 medical records of patients aged at most 18 years. These patients must have been hospitalized or have attended the day hospital of the child psychiatry centre of the Centre hospitalier universitaire de Quebec and have received an atypical antipsychotic between January 1, 2007 and December 31,2009. Results: Two hundred and thirty-six QTc were measured, representing the 40 subjects included in the study. The average QTc obtained under mono- therapy was 417 ± 26 msec. In total, 11% of QTc’s were considered abnormal in terms of absolute value and 1% in terms of difference from the initial value. A high dose of olanzapine (p=0.001) and of quetiapine (p=0.0036) and the presence of a pharmacodynamic interaction (p=0.028) were asso- ciated with a statistically significant increase in the risk of QTc interval prolongation. Conclusion: QTc interval prolongation was observed in a weak proportion of ECGs performed on children receiving atypical antipsychotics. Our study was useful in determining some associations related to the risk of QTc interval prolongation, such as high dose of an antipsychotic and the presence of drug interactions. Key words: atypical antipsychotic, QT interval, torsades de pointes, electrocardiogram, pediatrics