The risk of treatment-induced QT interval prolongation

Objective: QT interval prolongation can increase patients' hospital stay and mortality rate. This study aims to determine the incidence of drug-induced QT interval prolongation and establish which QT interval measurement method is the most appropriate for electrocardiographic monitoring. Method: A retrospective observational study was conducted of patients admitted to the Clinica Biblica Hospital during 2018. The electronic medical records of patients hospitalized for longer than 48 hours and whose drug regimen included at least one drug potentially able to prolong the QT interval were reviewed. Manually-measured QT intervals were corrected using Fridericia's and Rautaharju's formulae, while automatically-measured QT intervals were corrected with Bazett's formula. Risk was assessed using the RISQ-PATH scale. Results: Of the 141 patients analyzed, 23 had arrhythmia as per their clinical history and 14 suffered a complication during their stay in hospital. A total of 113 (80%) had a high RISQ-PATH score and only 64 were subjected to an electrocardiogram on admission. Patients received a mean of three potentially QT interval prolonging drugs. Most of the QT intervals measured automatically were shorter than those obtained manually. Of all corrections, the longest QTc interval values were obtained with Bazett's formula, and the shortest with Rautaharju's formula. None of the patients developed TdP or complex ventricular tachycardia. Conclusions: Every effort should be made to implement strategies con-ducive to more effective monitoring of the QT interval to prevent QT inter-val prolongation related complications in hospitalized patients.