Objectives: To analyse the incidence of long and short corrected QT (QTc) in healthy population of Changsha in China.
Methods: Standard 12-leads electrocardiogram (ECG) were performed on 4025 subjects in Changsha of China, who aged from six minutes after birth to 83 years old, between January 1993 to December 2012. Heart rate and QT interval were measured and recorded, Corrected QT (QTc) was calculated with Bazett´s formula (QTc = QT/RR0.5). All recruited individuals had taken healthy examination, ruling out general health issue, in the Second Xiangya Hospital of Central South University. Statistical analyses were performed with the SPSS 16.0 software.
Results: The incidence of short QTc was 6.88% (127/4 025 cases). The peak values of incidence were in the 30‒40 years old group (15.71%). The low values were in the 1‒3 month group, 3‒6 month group (0.76%), respectively. The incidence of long QTc was 3.16% (127/4 025 cases). The values diminished significantly after adulthood. The low values were in the 18‒30 years old group, 30‒40 years old group (0.86%，0.71%), respectively. After the age of 50, the incidence of long QTc increased with age (7.89%，9.06%，14.06%), respectively. There was no statistically significant difference between genders (p ˃ 0.05).
Conclusions: The peak incidences of long and short QTc existed in two separate age groups in healthy population. The peak incidence of short QTc was in 18‒40 years old group, the peak incidence of long QTc was in the group beyond 50 years old groups. For these two age groups, it was recommended to pay close attention to the changes of QTc in order to prevent cardiovascular events.
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