Assessment of QTc-interval Prolonging Medication Utilization and Associated Potential Drug-Drug Interactions in Hospitalized Cardiac Patients: A Cross-Sectional Study in Cardiology

Background: Several medications are linked to QTc-interval prolongation and torsades de pointes (TdP), a risk that is more common among hospitalized patients due to polypharmacy and associated QTc-interval-prolonging drug-drug interactions (QTc-pDDIs).
Objective: This study aimed to identify the prevalence of QTc-interval-prolonging drug (QTc-Drug) utilization and QTc-pDDIs among postoperative cardiac patients admitted to the National Institute of Cardiovascular Diseases (NICVD).
Method: We conducted a cross-sectional study at the NICVD, reviewing patients' medication charts for the use of QTc-Drugs and QTc-pDDIs. The CredibleMeds list was used to identify drugs associated with QTc-interval prolongation, while Micromedex Drug-Int.® and Lexicomp Interact® were utilized to screen for QTc-pDDIs.
Results: A total of 384 patients, with an average age of 48.9 ± 13.9 years, were included in the study. On average, patients used 10.3 ± 1.7 medications. Of the 3,956 medications prescribed, 22.9% were QTc-Drugs. The most frequently used QTc-Drug classes were diuretics (69.3%), anti-emetics (61.5%), and proton pump inhibitors (51.0%). Overall, 99.7% of patients received at least one QTc-Drug. The most frequent QTc-pDDI was ciprofloxacin-domperidone (7.6%), classified as major by Micromedex and a category B interaction by Lexicomp.
Conclusion: The prevalence of QTc-Drugs was very high among postoperative cardiac patients, with nearly all patients (99.7%) receiving at least one QTc-Drug. The most common QTc-pDDI was ciprofloxacin-domperidone (7.6%), identified as a major interaction by Micromedex and a category B interaction by Lexicomp. Category X (contraindicated) QTc-pDDIs should be avoided in hospitalized patients.