OBJECTIVE: Long QT syndrome (LQTS) poses a significant risk of torsade de pointes, particularly in older patients due to age-related changes in cardiac repolarization and increased susceptibility to medication-induced QTc interval prolongation. Despite the increased risk, data on medication-related LQTS remain limited, leading to this study on its prevalence, characteristics, and risk factors, along with QT-prolonging drug use in older patients. The study aims to identify clinical and medication-related predictors of LQTS and evaluate the burden of co-prescribed QT-prolonging medications in this population. SUBJECT AND METHODS: This prospective study at a tertiary care hospital included initial and follow-up ECGs, with medication details were collected. Statistical analyses compared variables, including QTc intervals and medication use, between patients with and without LQTS. RESULTS: The study included 128 adults aged 65 or older, with 27.3% presenting LQTS on admission, increasing to 42.2% after 7 days of hospitalization. Patients with LQTS had a higher prevalence of QTc-interval prolonging medications, List 1 medications, and atrial fibrillation. Laboratory changes and medication use were observed, with significant increases in QTc interval and List 1 medication administration. Male sex and amiodarone use were identified as predictors of LQTS during hospitalization. CONCLUSION: The study report a high prevalence of prolonged QTc interval and LQTS in older inpatients. Proton pump inhibitors were frequently prescribed despite their QTc-prolonging potential. This underscores the need of close monitoring and awareness of QTc prolongation risks in older patients, advocating for routine ECG assessments and vigilant management of modifiable risk factors, especially the electrolytes. .