• M Pasquier, O Pantet, O Hugli, E Pruvot, T Buclin, G Waeber, and D Aujesky.
• Division of General Internal Medicine, University of Lausanne, Lausanne, Switzerland. mathieu.pasquier@chuv.ch
• Intern Med J. 2012 Aug 1; 42 (8): 933-40.

BackgroundQT interval prolongation carries an increased risk of torsade de pointes and death.AimWe sought to determine the prevalence of QT prolongation in medical inpatients and to identify determinants of this condition.MethodsWe enrolled consecutive patients who were admitted to the internal medicine ward and who had an electrocardiogram performed within 24 h of admission. We collected information on baseline patient characteristics and the use of QT-prolonging drugs. Two blinded readers manually measured the QT intervals. QT intervals were corrected for heart rate using the traditional Bazett formula and the linear regression-based Framingham formula. We used logistic regression to identify patient characteristics and drugs that were independently associated with QTc prolongation.ResultsOf 537 inpatients, 22.3% had a prolonged QTc based on the Bazett formula. The adjusted odds for QTc prolongation based on the Bazett correction were significantly higher in patients who had liver disease (OR 2.9, 95% CI: 1.5-5.6), hypokalaemia (OR 3.3, 95% CI: 1.9-5.6) and who were taking ≥1 QT-prolonging drug at admission (OR 1.7, 95% CI: 1.1-2.6). Overall, 50.8% of patients with QTc prolongation received additional QT-prolonging drugs during hospitalisation.ConclusionsThe prevalence of QTc prolongation was high among medical inpatients but depended on the method used to correct for heart rate. The use of QT-prolonging drugs, hypokalaemia and liver disease increased the risk of QTc prolongation. Many patients with QTc prolongation received additional QT-prolonging drugs during hospitalisation, further increasing the risk of torsade de pointes and death.© 2011 The Authors. Internal Medicine Journal © 2011 Royal Australasian College of Physicians.

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