Association between a prolonged corrected QT interval and outcomes in patients in a medical Intensive Care Unit
Tarun K. George, David Chase, John Victor Peter, Sowmya Satyendra, R. Kavitha, Leah Raju George, Vineeth Varghese Thomas
electrocardiography, India, intensive care unit, predictors, QT prolongation,Critical care
Citation Information :
George TK, Chase D, Peter JV, Satyendra S, Kavitha R, George LR, Thomas VV. Association between a prolonged corrected QT interval and outcomes in patients in a medical Intensive Care Unit. Indian J Crit Care Med 2015; 19 (6):326-332.
Introduction: Patients admitted into a medical Intensive Care Unit (ICU) have varying illnesses and risk factors. An electrocardiogram (ECG) is a useful tool to assess the cardiac status. The aim of the study was to determine the prevalence of QT prolongation of the ECG in patients admitted to a medical ICU in a tertiary hospital, to assess outcomes in terms of mortality, cardiovascular events, and duration of ICU stay. Materials and Methods: Prospective observational study, 6 months duration, assessing the prevalence of prolonged corrected QT interval (QTc) at admission into a medical ICU. A QTc calculated by Bazett′s formula, of >440 ms for males and >460 ms for females was considered prolonged. Details of illness, clinical and lab parameters were monitored. Results: The total number of patients screened was 182. There was a high prevalence of prolonged QTc (30%) on admission to the ICU. This reduced to 19% on day 3 (P = 0.011). In patients with a prolonged QTc the odds ratio of adverse outcome from ICU was 3.17 (confidence interval [CI]: 1.52-6.63) (P = 0.001) and of adverse outcome for hospital stay was 2.27 (CI: 1.11-4.66) (P = 0.014). In the study, 35% of all patients received drugs with QT prolonging action. Of patients with a prolonged QTc at admission 18 (35%) received a QT prolonging drug. Conclusions: We found that prolonged QTc is common (30%) in our medical ICU at admission and a large proportion (35%) received drugs capable of prolonging QT interval. These patients with QTc prolongation have a higher odds ratio for adverse outcomes.
Goldhill DR, Sumner A. Outcome of intensive care patients in a group of British intensive care units. Crit Care Med 1998;26:1337-45.
Knaus WA, Draper EA, Wagner DP, Zimmerman JE. APACHE II: A severity of disease classification system. Crit Care Med 1985;13:818-29.
Ferreira FL, Bota DP, Bross A, Mélot C, Vincent JL. Serial evaluation of the SOFA score to predict outcome in critically ill patients. JAMA 2001;286:1754-8.
Le Gall JR, Lemeshow S, Saulnier F. A new Simplified Acute Physiology Score (SAPS II) based on a European/North American multicenter study. JAMA 1993;270:2957-63.
Haugaa KH, Bos JM, Tarrell RF, Morlan BW, Caraballo PJ, Ackerman MJ. Institution-wide QT alert system identifies patients with a high risk of mortality. Mayo Clin Proc 2013;88:315-25.
Pickham D, Helfenbein E, Shinn JA, Chan G, Funk M, Weinacker A, et al. High prevalence of corrected QT interval prolongation in acutely ill patients is associated with mortality: Results of the QT in Practice (QTIP) Study. Crit Care Med 2012;40:394-9.
Tisdale JE, Wroblewski HA, Overholser BR, Kingery JR, Trujillo TN, Kovacs RJ. Prevalence of QT interval prolongation in patients admitted to cardiac care units and frequency of subsequent administration of QT interval-prolonging drugs: A prospective, observational study in a large urban academic medical center in the US. Drug Saf 2012;35:459-70.
Mabasa VH, Yokoyama S, Man D, Martyn J. Analysis of Orders for QTc-Prolonging Medication for Intensive and Cardiac Care Unit Patients with Pre-existing QTc Prolongation (QTIPPP Study). Can J Hosp Pharm 2011;64:412-8.
Garson A Jr. How to measure the QT interval - What is normal? Am J Cardiol 1993;72:14B-16.
Goldenberg I, Moss AJ, Zareba W. QT interval: How to measure it and what is normal. J Cardiovasc Electrophysiol 2006;17:333-6.
Available from: http://www.medicine-on-line.com/html/ecg/e0001en_files/05.htm.
Available from: http://www.en.ecgpedia.org/wiki/File: LastigeQT1.png.
Moss AJ. Long QT syndrome. JAMA 2003;289:2041-4.
Al-Khatib SM, LaPointe NM, Kramer JM, Califf RM. What clinicians should know about the QT interval. JAMA 2003;289:2120-7.
Ng TM, Olsen KM, McCartan MA, Puumala SE, Speidel KM, Miller MA, et al. Drug-induced QTc-interval prolongation in the intensive care unit: Incidence and predictors. J Pharm Pract 2010;23:19-24.
Kozik TM, Wung SF. Acquired long QT syndrome: Frequency, onset, and risk factors in intensive care patients. Crit Care Nurse 2012;32:32-41.
Shadnia S, Okazi A, Akhlaghi N, Sasanian G, Abdollahi M. Prognostic value of long QT interval in acute and severe organophosphate poisoning. J Med Toxicol 2009;5:196-9.