Assessment of Drug Induced QT Interval Prolongation at a tertiary care, Baptist Hospital, Bangalore

Aim: To investigate the drug induced QT-interval prolongation in hospital inpatients, predictors of risk factor for QT-interval prolongation and drug-drug interactions. Methodology: It is a prospective observational study conducted in inpatient setting. The data collected in pre design data collection form for 110 patients, who are assessed for the period of six months. The prescription with at least one QT-interval prolonging drugs were considered for this study. The collected data included demographics, mean change in QT-interval with drugs, ECG data and safety analysis data. Result: The total number of patients screened was 110. Among the study patients most of them 50.91% were older age. Major co-morbidities were diabetes mellitus 39(35.45%) and hypertension 36(32.72%). There was a high prevalence (46.45%) of QT-interval prolongation. The mean QTc in prolonged group was 495 +/- 34.4ms. Ondansetron (61.18%), Metronidazole (58.18%), Ciprofloxacin (20.9%), Azithromycin (16.36%) and Domperidone (11.81%) were associated with marked QTc-interval prolongation. Female sex, longer hospitalization, electrolyte abnormalities and older age were associated with drug induced QT-interval prolongation. 97(88.18%) prescriptions showed drug interaction involving QT-interval prolongation. The most common drug interaction was found to be between ondansetron and metronidazole in 41 prescription followed by ondansetron and ciprofloxacin in 15 prescriptions. Of the 97 interventions proposed, the most frequent suggestion was on stop/avoid/dose adjustment (13.40%) followed by ECG monitoring (10.40%). 16.49% of interventions were accepted Conclusion: This study demonstrates the high prevalence of a prolonged QT-interval in patients. Cardiac drugs and antibiotics were frequently involved in drug induced QT-interval prolongation. A simple ECG and a calculated QT interval can be used to plan management and caution consultant on probable electrolyte abnormalities and drug therapies. The current study demonstrated the importance of routine medication review and the need of a pharmacist in a multidisciplinary team.