Mechanisms and Risks of Electrocardiographic QT Interval Prolongation When Using Antipsychotic Drugs

This article reviews cardiac electrophysiology, with a focus on the assessment of the electrocardiographicallydetermined corrected QT (QTc) interval and its role as a marker for potentially lifethreateningcardiac arrhythmias such as torsades de pointes. Presently, using the QTc interval as a surrogatefor polymorphic ventricular tachycardia is handicapped, in part, by the limitations of currentlyavailable group-derived formulas to estimate the QTc interval. Regulatory agencies have sharpenedtheir interest in this arena. Substantial progress almost certainly awaits the application of individualrather than group-derived formulas to estimate the QTc interval. Until this refinement arrives, cliniciansare advised to exercise caution when administering antipsychotic drugs with the potential tosignificantly prolong the QT interval. Caution is particularly urged in patients with cardiovasculardisease or risk factors for cardiovascular disease.