Pharmacist-driven Evaluation of QTc Interval Prolongation in Cardiac Patients: Integrating Rautaharju’s Heart Rate Correction Formula and the Tisdale Risk Score

Objectives: In critically ill patients, the hazard of developing torsade de pointes (TdP) is a major concern. These patients are often on multiple medications and are liable to heart-rate corrected QT interval (QTc) prolongation, which can lead to fatal arrhythmias. This highlights the significance of monitoring the QTc and evaluating the risk to prevent such complications. The study aimed to evaluate a pharmacist-driven assessment of QTc prolongation using Rautaharju’s heart-rate-corrected formula and the Tisdale risk score (TRS) for the stratification of TdP risk. Material and Methods: We conducted an observational study at the National Institute of Cardiovascular Diseases in Karachi, enrolling 485 adult patients between November 2022 and August 2023. QTc intervals were manually calculated using Rautaharju’s formula from electrocardiographic lead II and V5. We applied the TRS both before and after the pharmacist’s interventions and used logistic regression to identify the key predictors of QTc prolongation. Results: The prevalence of prolonged QTc was 28.6%, with 4.1% crossing the critical threshold of QTc ≥500 ms. Among individual TRS components, hypokalaemia (OR: 1.55, 95% CI: 1.03–2.32, p =0.035) was a significant risk factor of QTc prolongation. Pharmacist interventions led to a significant shift in patient risk, reducing the proportion of prolonged QTc patients in the high-risk TRS category from 57.6% pre-intervention to 30.2% post-intervention. Conclusion: This study demonstrates that a pharmacist-led approach to QTc assessment can effectively identify and reduce arrhythmia risks in patients. By incorporating Rautaharju’s formula and the TRS into clinical care, we can make more informed decisions, potentially reducing the occurrence of drug-induced arrhythmias and improving patient safety.