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 electrocardiographically determined corrected QT (QTc) interval and its role as a marker for potentially life-threatening cardiac arrhythmias such as torsades de pointes. Presently, using the QTc interval as a surrogate for polymorphic ventricular tachycardia is handicapped, in part, by the limitations of currently available group-derived formulas to estimate the QTc interval. Regulatory agencies have sharpened their interest in this arena. Substantial progress almost certainly awaits the application of individual rather than group-derived formulas to estimate the QTc interval. Until this refinement arrives, clinicians are advised to exercise caution when administering antipsychotic drugs with the potential to significantly prolong the QT interval. Caution is particularly urged in patients with cardiovascular disease or risk factors for cardiovascular disease.