Background Previous studies reported that hypo‐ and hyperthermia are associated with several atrial and ventricular electrocardiographical parameters, including corrected QT (QTc) interval. Enhanced characterization of variations in QTc interval and normothermic body temperature aids in better understanding the underlying mechanism behind drug induced QTc interval effects. The analysis’ objective was to investigate associations between body temperature and electrocardiographical parameters in normothermic healthy volunteers. Methods Data from 3023 volunteers collected at our center were retrospectively analyzed. Subjects were considered healthy after review of collected data by a physician, including a normal tympanic body temperature (35.5‐37.5°C) and in sinus rhythm. A linear multivariate model with body temperature as a continuous was performed. Another multivariate analysis was performed with only the QT subintervals as independent variables and body temperature as dependent variable. Results Mean age was 33.8 ± 17.5 years and mean body temperature was 36.6 ± 0.4°C. Body temperature was independently associated with age (standardized coefficient [SC] = −0.255, P < .001), female gender (SC = +0.209, P < .001), heart rate (SC = +0.231, P < .001), P‐wave axis (SC = −0.051, P < .001), J‐point elevation in lead V4 (SC = −0.121, P < .001), and QTcF duration (SC = −0.061, P = .002). In contrast, other atrial and atrioventricular (AV) nodal parameters were not independently associated with body temperature. QT subinterval analysis revealed that only QRS duration (SC = −0.121, P < .001) was independently associated with body temperature. Conclusion Body temperature in normothermic healthy volunteers was associated with heart rate, P‐wave axis, J‐point amplitude in lead V4, and ventricular conductivity, the latter primarily through prolongation of the QRS duration.

Introduction Previous studies have observed that hypo- and hyperthermia are associated with several atrial and ventricular electrocardiographical parameters, including the corrected QT interval. Preclinical studies have shown that drugs that exert an effect on body temperature also exert an effect on the corrected QT interval. Therefore, increased characterization in healthy humans of the association between the corrected QT interval and body temperature within the normal body temperature range aids in understanding the mechanism behind drug induced corrected QT interval effects. The objective of this analysis was to evaluate the association between body temperature and electrocardiographical parameters in normothermic healthy volunteers. Methods Data from 3023 volunteers collected at our center were analyzed. Only subjects considered healthy after review of collected data by a physician, including a normal tympanic body temperature (35.5–37.5 °C) and in sinus rhythm, were included in the analysis. Subjects were divided into body temperature quartiles for analysis and a linear multivariate model with body temperature as a continuous was performed. Another multivariate analysis was performed with only the QT subintervals as independent variables and body temperature as dependent variable. Results Mean age was 33.8±17.5 years and mean body temperature was 36.6±0.4 °C. Body temperature was independently associated with age (standardized coefficient (SC)=−0.252, P&lt;0.001), gender (SC=+0.208, P&lt;0.001), heart rate (SC=+0.230, P&lt;0.001), J-point elevation in lead V4 (SC=−0.118, P&lt;0.001), and Fridericia corrected QT interval (SC=−0.061, P=0.002). Atrial and AV nodal parameters were not independently associated with body temperature. The effects of temperature on the surface ECG are displayed in figure 1. QT subinterval analysis revealed that only QRS duration (SC=−0.121, P&lt;0.001) was independently associated with body temperature. Conclusion Body temperature in normothermic healthy volunteers was associated with heart rate, J-point amplitude in lead V4 and ventricular conductivity, primarily through a prolongation of the QRS duration. In contrast, atrial and AV nodal ECG parameters were not independently associated with body temperature. Funding Acknowledgement Type of funding source: None