High prevalence of the risk factors for QT interval prolongation and associated drug–drug interactions in coronary care units

ABSTRACT

Objectives: Patients admitted in coronary care units are susceptible to QT interval prolongation due to numerous risk factors. The purpose of this study was to identify the prevalence of risk factors for QT interval prolongation; QT prolonging medications; drug–drug interactions; their predictors; and torsades de pointes risks of drugs.

Methods: After obtaining approval, this cross-sectional study was carried out during one-year period in coronary care units of two major tertiary care hospitals of Khyber Pakhtunkhwa, Pakistan. The Arizona Center for Education and Research on Therapeutics QT drugs lists and Micromedex DrugReax® were used to identify the QT prolonging medications and QT prolonging drug–drug interactions.

Results: Total 649 patients were included in this study. The most frequent QT prolonging risk factors included use of ≥ 1 QT prolonging drugs (74.9%) and myocardial infarction (61.3%). Total 181 patients were presented with 361 QT prolonging drug–drug interactions. There was significant association of the occurrence of QT prolonging drug–drug interactions with female gender (p = 0.01), 9–10 prescribed medications (p = 0.001), and > 10 prescribed medications (p < 0.001).

Conclusions: The majority of patients presented with multiple risk factors for QT prolongation in coronary care units which may precipitate lethal outcomes.

KEYWORDS:

• QT prolongation
• torsades de pointes
• QT prolonging drugs
• coronary care unit
• QT prolonging drug–drug interactions

Acknowledgments

The authors are very grateful to hospital administration, physicians, and all other staff for their cooperation in this study.

Declaration of funding

This manuscript was not funded.

Declaration of financial/other relationships

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties. Peer reviewers on this manuscript have no relevant financial relationships to disclose.