The aim of the study is to evaluate the association of QTc cutoff, gender, race, and age on reporting of QTc interval prolongation.
Retrospective study of 147 patients admitted to our hospital or ER visit from January 2016 to May 2020. Simple descriptive statistics and longitudinal linear mixed model was performed on the 213 total observations from 147 patients.
The average age of the patients was 65 (±17.8, 18-98) years. Females were 32% (n=47) and Hispanics 78.4% of sample. QTc prolongation was reported in 65% (n=138) of the 213 EKG’s. Calculated 90th and 99th percentile for QTC is 522 and 586 milliseconds respectively. Unadjusted, QTc > 480 millisecond is 1.7 times more likely to be reported as prolongation (p=0.08) while, QTc >90th is 2.37 times more likely to be reported as a prolongation (p=0.07). With every year increase in age, the interpretation of prolonged QTc is 2% less likely (OR= 0.98, p= 0.04). After adjusting for age and gender, reporting of prolongation is 2.38 times more likely with QTc >480 milliseconds (p=0.01) and 2.66 times more likely with QTc >90th percentile (p=0.06).
For the same value of QTc, the odds of reporting of QTc prolongation is less likely for older patients. After adjusting for age and gender, the odds of prolonged QTc reporting is more than two times higher for >480 and >522 milliseconds. Our study provides evidence that greater guidance on prolongation reporting should be considered to ensure more consistent reporting of prolongation.
Thunuguntla, S., & Machiorlatti, M. (2020). QTc Cutoff, Gender, Race and Age on Reporting of Prolonged QTc. American Heart Journal, 229, 170. https://doi.org/10.1016/j.ahj.2020.10.033