Dispersion of the corrected QT interval in the electrocardiogram of the ex-prisoners of war

The study of electrocardiograms (ECGs) was performed in a subgroup of 181 men, ex-prisoners of war with mean age 35.8±11.0 years and mean duration of imprisonment 164.5±87.1 days, chosen at random from the total sample of released prisoners (N=1458). The control group was pair-matched. The analysis of ECGs was done according to the Minnesota code, and Bazett’s formula gave the values of the corrected QT interval (QTc). The dispersion of the QTc interval is determined by the difference between the longest and the shortest measured QTc interval in each ECG lead. The results of descriptive statistics in the group of ex-prisoners showed the range of QTc dispersion of 8.0–122.0 ms (mean 52.4±21.6 ms), while in the control group the range was 6.0–72.0 ms (mean 30.4±13.8 ms) (df=360, t=11.536; P<0.001). The QTc interval from 422.0 to 480.0 ms had 60.2% ex-prisoners and 30.4% controls, while a QTc interval over 480.0 ms had 19.3% ex-prisoners and 1.10% controls (P<0.0001). In the ex-prisoners group, the QTc dispersion over 50 ms was present in 51.4%; of those, a dispersion of 95 ms and more was found in 3.9%, while in the controls a QTc dispersion over 50 ms was found in 8.3%, but a dispersion of 95 ms and more was not recorded (P<0.0001). The odds ratio estimated for the prolonged QTc interval was 8.467 and for enlarged QTc dispersion it was 11.695 in the ex-prisoners versus controls (P<0.001). In conclusion, persons exposed to long-term maltreatment in detention camps have significantly greater QTc dispersion, as well as a higher relative risk of prolonged QTc interval and greater QTc dispersion than a control group.