Gender and QT interval

 Q;  Which gender tends to have a higher propensity to have a prolonged QT interval? (select one)

A) Males

B) Females

Answer: B

The 99th percentile of QTc value in an adult male has a QT interval on average of 470 milliseconds and an adult female of 480 milliseconds. This makes the female gender more prone to develop prolong QT-related arrhythmias. This also explains why females are more at risk of Torsades de Pointes (TdP) with sotalol and other commonly prescribed anti-arrhythmic drugs. Female sex is considered the highest risk factor for drug-induced TdP. 

The objective of the above question is to highlight the American Heart Association/American College of Cardiology (AHA/ACC) scientific statement on the prevention of TdP in hospital settings that a QTc over the 99th percentile should be considered abnormally prolonged.

#cardiology

References:

1. Drew BJ, Ackerman MJ, Funk M, et al. Prevention of torsade de pointes in hospital settings: a scientific statement from the American Heart Association and the American College of Cardiology Foundation. Circulation 2010; 121:1047. 

2. Lehmann MH, Hardy S, Archibald D, et al. Sex difference in risk of torsade de pointes with d,l-sotalol. Circulation 1996; 94:2535. 

3. Makkar RR, Fromm BS, Steinman RT, et al. Female gender as a risk factor for torsades de pointes associated with cardiovascular drugs. JAMA 1993; 270:2590. 

4. Drici MD, Clément N. Is gender a risk factor for adverse drug reactions? The example of drug-induced long QT syndrome. Drug Saf 2001; 24:575.