Qt-Prolongation Associated with Medication Combination in Hospitalized Patients at Johns Hopkins Aramco Healthcare (JHAH), KSA
Authors: Alhabib Mohammed , Alhumaid Rahmah Majed , Alenezi Abdullah Mohammed G. , Alanazi Renad Huwaydi 
Published: March 2022

Background: Long QT syndrome (LQTS) is a myocardial repolarization dysfunction characterized by QT-interval prolongation on electrocardiogram (ECG). Patients with long QT syndrome have a corrected QT interval (QTc) prolongation greater than 460 milliseconds (0.46 seconds). The long QT syndrome has a direct association with an increased risk of a serious type of arrhythmias called ‘Torsades de Pointes (TdP)’, a polymorphic ventricular tachycardia. QT-interval prolongation and the consequent life-threatening Torsade de Pointes may develop in both outpatient and inpatient setting, however, the risk is thought to be higher among hospitalized patients. This is mainly because admitted patients usually receive multiple drugs and may have other risk factors, including electrolyte disturbances and hepatic or renal impairment. This study is an attempt to address the issue of QT-prolongation and its prevalence among hospitalized patients, and evaluate the safety of prescribing patterns of QT-prolonging drugs selected in the study. The aim is to determine which drugs physicians more commonly prescribe and whether or not they cause long QT-interval in patients. Our paper also aims to provide general recommendations for a safer practice. We aim to extend the current knowledge and highlight this overlooked adverse effect in the clinical practice.

Methods: This retrospective study was conducted based on electronic health records (EHRs). The Institutional Review Board (IRB) of Johns Hopkins Aramco Hospital approved the study. The data were extracted from EPIC healthcare system at Johns Hopkins Aramco Healthcare (JHAH) in Dhahran, Saudi Arabia on 122 hospitalized patients. The statistical software program GraphPad Prism 9.0.0 version was used to analyze and generate the figures.

Results: Nearly half of them (51.6%) were arrhythmic patients. The duration of therapy was also considered, and we found that the majority of patients were on a short-term therapy (76.2%). Two-drug regimen was the most commonly observed (46.6% of patients), whereas nearly 30% were prescribed three or more QT-prolonging drugs. In respect to drug classes, the serotonin antagonist drug (ondansetron) was the most commonly prescribed agent among our patient population (69.6%). The corrected QT-interval (ECG reading) varied among patients; however, all subjects experienced QT-prolongation with varying degrees. Fifty-five per cent of patients fell into the 440-469 ms category, 22.9% were borderline (470-499 millisecond) and 12.3% had a clinically significant long QT syndrome (≥500 millisecond).

Conclusion: A substantial number of patients presented with drug-induced QT prolongation with varying degrees. Scores of ≤500 ms does not mean nor eliminate the risk of developing fatal arrhythmias. Proper considerations are needed in order to optimize and minimize the use of drugs that are associated with long QT syndrome. This adverse effect usually goes undetected in real-world practice. ECG monitoring should be recommended in patients who are receiving two or more QT-prolonging drugs, elderly, and/or have other risk factors.