The impact of fever on corrected QT interval

We were interested in the impact of fever on the QT interval as information on this subject is limited.

We performed a retrospective, single centre study over a two year period, ending December 31st, 2013. Participants were identified using an electronic chart review of emergency department records linked to an ECG data base. Study subjects were drawn from patients presenting with fever to an academic emergency department in Canada. Our study identified febrile (T>38.0°C) patients aged >18years presenting to our centre. Included participants must have had an ED based ECG at the time of presentation with fever and a comparison ECG performed within 30days and without fever. Actively paced patients were excluded. QT values were corrected using Bazett's, Fridericia's and The Framingham Formula. QT values for febrile and afebrile cohorts were compared using Related-Samples Wilcoxon Signed Rank Test.

181 patients satisfied our inclusion/exclusion criteria, 54.1% were female and mean age was 68.9years old. Mean duration between febrile and afebrile ECGs was 6.1days. The median corrected QT interval (QTc) was significantly shorter in patients during their febrile presentation, as compared to their afebrile presentation when correcting for QT using both Framingham [QTc=466.1ms (445.8-499.5) vs. 507.6 (476.0-539.0); p<0.001] and Fridericia's formula [QTc=388.7ms, (371.5-407.5) vs. 406.7ms, (386.1-434.4); p<0.001]. This difference was independent of gender.

We found fever to shorten the QTc independently of sex in a general emergency department population.