Prescribing Practices of QT Interval Prolonging Drugs in Critically Ill Older Adults in South India.

Background It was Dissertenne who first described a cardiac phenomenon known as the Torsades de Pointes (TdP). QT prolongation caused by drugs is one of the most important causes for acquired QT prolongation syndrome. Objective To observe the prescribing practices of QT interval prolonging drugs among a highrisk population of critically ill older adults in a tertiary care hospital in South India The objectives were to identify the most commonly prescribed QT prolonging drugs, to analyse types of QT prolonging drugs based on risk of causing QT prolongation, to study the frequency of occurrence of common risk factors for QT prolongation and to identify presence of any significant relationships among the study variables. Method We have conducted a one-year cross-sectional descriptive study of the prescribing practices of QT interval prolonging drugs among 319 critically ill older adults in a tertiary care hospital in South India. Data was analysed to categorize the most common drugs which prolong QT interval; the type and frequency of use of QT interval prolonging drugs and to find the most common risk factors for QT prolongation in this study population. Result In this study, ondansetron, clarithromycin, azithromycin,and amiodarone were the most prescribed among the drugs with known risk of QTc (Corrected QT interval) prolongation. Among the drugs with conditional risk of QTc prolongation, pantoprazole, frusemide, piperacillin-tazobactam and esomeprazole were the most prescribed. The most common risk factors for QTc prolongation that were identified in this study were bradycardia, acute kidney injury, chronic kidney disease and low serum potassium. Conclusion This study helps to inform our physicians regarding the commonly prescribed QT interval prolonging drugs so that they may reduce co prescription of multiple QT prolonging drugs in high-risk patients. It identifies kidney injury, low potassium, and bradycardia as common risk factors for QT interval prolongation in these patients.