Author`s Reply.

To the Editor,

A review of the literature regarding the QTc values of patients in the control group revealed the following observations: Trolle et al.’s (1) study had a control group with a mean age of 38.9±12.4 years, with mean QTc values of 389.1±20.1; Demirol et al.’s (2) study had a control group with a mean age of 12±3.5 years, with mean QTc values of 390±25.1; Olivares López et al.’s (3) study had a control group with a mean age 11.45±2.58 years, with mean QTc values of 391.73±17.7; Ergul et al.’s (4) study had a control group with a mean age of 4.3 (6 days–16 years) years, with mean QTc values of 385±58; Küçük et al.’s (5) study had a control group with a mean age of 60 years, with mean QTc values of 384±43.2; Braschi et al.’s (6) study, which shows reference ranges for non-invasive ventricular repolarization parameters for various patients, had 3 groups: group 1–child (1 day–11 years), group 2–adolescent (12–19 years), group 3–adult (20–64 years). Group 1 had a mean QTc value of 401.7±25, group 2 401.9±21.3, and group 3 407.3±19.8; Akın et al.’s (7) study had a control group with a mean age of 8.8±2.4 years, with min QTc of 371.3±24.7 and max QTc of 411.33±24.6; Ogawa et al.’s (8) study in Japan entitled “The Maximum QTc of Holter Electrocardiography in a Pediatric Population” had a QTc value of 380 (368–390) for 10–12-year-old girls and 397 (380–410) for 13–15-year-old girls; and Krasemann et al. (9) had 7 groups in their study entitled “Changes of the corrected QT interval in healthy boys and girls over day and night,” wherein the sixth group with patients aged 12–16 years had a QTc value of 400±20.

Our control group with patients aged 13.17±2.85 years had a mean QTc value of 392.06±13.21, which is not different from those in the 9 studies mentioned above but clearly different from the Brazilian study. Regional factors may be the cause of this difference; therefore, everyone including us use control groups of same population we studied. We indicated that our study population was small and that studies with a larger population are necessary along with the other limitations in the study limitations section.

Our study did not evaluate mortality, and our results indicate the differences only between the study and control groups. Because QTc prolongation can cause sudden and we did find longer QTc in our study population, we only mention that the increased QTc may cause harm and to confide in that we suggested further investigation.