QT interval

Abstract

Background: Occupational factors are likely to contribute to increased cardiovascular disease risk among emergency medical responders (EMR). The aim of this study was to clarify whether EMR stressful Job and their prolonged exposure to work stress are associated with an increase in QT interval and QT dispersion. Methods: A comparative cross sectional study was conducted upon 137 EMR and a 119 matched control group composed of non-emergency workers. All study population were subjected to history taking for age, risk factors such as diabetes mellitus, hypertension, and smoking, history of cardiovascular disease, and the use of medications. Measurement of blood pressure, and body mass index (BMI) was recorded. Standard 12-lead ECGs were recorded for the analysis of heart rate (HR), QT, QTc, QT dispersion, Tpeak and Tend (Tpe), and Tpe dispersion. In addition the levels of epinephrine and nor-epinephrine hormones in urine during the work shift were analyzed. Results: High risk EMR had a significant increase in blood pressure, urinary epinephrine and norepinephrine compared to the control group (p < 0.05). There were no differences between studied groups as regards heart rate, QT, QTc, QT dispersion, QTc dispersion, Tpe interval, and Tpe dispersion with no significant correlation between catecholamine levels and QTc interval. Conclusion: QTc and dispersion were not increased among emergency medical responders in spite of having higher catecholamine levels.

Keywords

• QT interval
• Emergency medical responders
• Work stress