Key result
Women have ~11 ms longer mean QT and QTc intervals than men.
Why the study?
Although the impact of age and gender on QT and QTc intervals on conventional ECG is well established, their impact on mean QT and QTc intervals measured with ambulatory ECG monitoring has not been studied.
Do age and gender impact mean QT and QTc intervals measured with ambulatory ECG monitoring in patients without significant cardiac abnormalities?
Do age and gender impact mean QT and QTc intervals measured with ambulatory ECG monitoring in patients without significant cardiac abnormalities?
Female gender and increasing age are associated with longer mean QT and QTc intervals on ambulatory ECG monitoring, establishing normal ranges for this modality.
Women had longer QT/QTc on ambulatory ECG; leaves open whether gender-specific norms should guide practice pending validation.
Although the impact of age and gender on QT and QTc intervals on conventional electrocardiogram (ECG) has been well studied, the impact of these factors on mean QT and QTc intervals measured with ambulatory ECG monitoring has not been studied. The aim of this study was to assess the impact of age and gender on mean QT and QTc intervals measured with ambulatory ECG monitoring. Recordings of ambulatory ECG monitoring from 380 patients without significant cardiac abnormalities were analysed. The mean QT interval was longer in women (390.5 [373.0–405.0] ms) than in men (380.0 [366.0–397.5] ms) (p<0.001). The mean QTc interval was also longer in women (439.0 [429.0–447.5] ms) than in men (428.5 [417.0–441.0] ms) (p<0.001). The normal (2.5–97.5 percentiles) mean QTc interval measured with ambulatory ECG monitoring ranged from 393 to 466 ms in men and from 411 to 471 ms in women. QT and QTc intervals increased with age (p<0.001). There was a positive correlation between age and QT interval (r=0.474, p<0.001) as well as between age and QTc interval (r=0.263, p<0.001). Thus, female gender is associated with longer mean QT and QTc intervals measured with ambulatory ECG monitoring. QT and QTc intervals become longer with age.
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Skakun et al. (2026) studied this question. Women had a mean QT interval of 390.5 ms and mean QTc interval of 439.0 ms, both significantly longer than men's values (380.0 ms and 428.5 ms, p<0.001).
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