Assessment of pharmacist-driven QT interval prolongation in cardiac patients: Application of Framingham's heart rate corrected QT interval formula and the Tisdale risk score

Abstract

QTc interval prolongation is a clinical concern in critically ill cardiac patients. Pharmacist-driven approaches that utilize accurate QTc interval measurements and risk stratification tools are essential for identifying high-risk patients and preventing arrhythmic events. This study evaluates the application of Framingham's heart rate corrected QT interval (QTc) formula and the Tisdale risk score for identifying QTc interval prolongation. This prospective observational study was conducted at the National Institute of Cardiovascular Diseases (NICVD), Karachi, Pakistan. A total of 485 patients were analyzed. Of 485 patients, 71 (14.6%) exhibited QTc interval prolongation. Among them, 6 (1.2%) exhibited severe QTc interval prolongation, with values >500 ms. The Tisdale risk score classified 67.6% of the patients as high-risk before the intervention, and reduced to 36.6% post-intervention. Older patients (≥60 years) were significantly more likely to exhibit QTc interval prolongation, particularly in the >500 ms. Risk factors for QTc interval prolongation included female sex, hypokalemia, and the use of multiple QTc interval prolonging medications. This study underscores the importance of combining Framingham's formula and the Tisdale risk score, with pharmacist involvement, to accurately assess QTc interval prolongation and optimize patient management, enhancing safety and reducing arrhythmic risk in critically ill cardiac patients.