Russell H, et al. - In this prospective observational study, researchers focused on the incidence, predictors as well as consequences of QTc [the QT interval duration corrected for heart rate according to Bazett's formula (QTc  =  QT/(RR)^1/2)] prolongation (≥ 500 ms) during ICU admission. Participants were 257 patients who were admitted to a tertiary ICU during a two-month period. Of these, the occurrence of ≥ 1 episode of QTc ≥ 500 ms was reported in 93 (36.2%). Having higher Acute Physiology and Chronic Health Evaluation II scores, taking more QT-prolonging medications, and more often suffering non-sustained and sustained ventricular tachycardia, were observed in such patients. However, no independent link between QTc duration and odds of ventricular tachyarrhythmia was found following adjustment for confounders. Moreover, the spontaneous resolution of 98% of ventricular tachyarrhythmias was documented. Longer ICU and hospital length-of-stay, and greater ICU and in-hospital death were reported in patients with QTc prolongation. In no case, sustained Torsades de Pointes or death from ventricular arrhythmia was reported. Overall, a QTc ≥ 500 ms possible serves as a marker of illness severity changed by various risk factors and demonstrated no independent link with clinically-significant ventricular tachyarrhythmias. Therefore, there may be no clinical benefit of stopping QT-prolonging medications to prevent arrhythmias.