The importance of correct QTc measurement in elderly patients treated with QT interval prolonging drugs.

J U L Y 2 0 1 4 , V O L . 7 2 , N O 6 © Van Zuiden Communications B.V. All rights reserved. To the Editor, We read with interest the recently published article by Kan et al. In this review, the authors address the identification and management of drug-intoxicated patients who may be at risk for prolongation of the QT interval corrected for heart rate (QTc) and possible torsades de pointes (TdP). They recommend a stepwise approach that includes identifying which QTc interval-prolonging drugs are involved and if additional risk factors are present, correct determination of the QTc interval using the Hodges or Frederica formula, and when indicated initiating monitoring and treatment. While this review focuses on the intoxicated patient, this is also very important in the hospitalised elderly patient. Elderly patients may be more vulnerable for drug-induced QTc prolongation and consequently at risk for TdP since the QTc interval is known to increase with age. Additionally, they often have other risk factors for QTc interval prolongation present such as myocardial damage, polypharmacy (e.g. use of class Ia or III antiarrhythmic agents, and specific antidepressants), or electrolyte disturbances. Several safety concerns have been raised for use of QTc interval-prolonging drugs such as fluoroquinolones and antipsychotics in elderly patients. The antipsychotic haloperidol, currently the treatment of choice for most delirium, may induce QTc prolongation. With delirium prevalence rates of more than 30% in older general internal medicine patients, treatment initiation with haloperidol or other antipsychotics known to prolong the QTc interval in elderly patients is daily practice for many physicians. To date, there is no accepted standard for risk assessment and monitoring of elderly patients subjected to drugs that may potentiate QTc prolongation and TdP. We are currently conducting a multicentre double-blind placebo-controlled randomised clinical trial (The HARPOON study; NCT01530308) to study the effects of L E T T E R T O T H E E D I T O R