[QTc interval in the neonatal period in a Mexican population. A pilot study].

Introduction: QT interval prolongation is associated with ventricular arrhythmias and sudden death syndrome.

Objective: To determine the value of QTc interval in healthy newborns in a general hospital in Jalisco, Mexico, and their outcome during their first months of life.

Methods: The study included healthy newborns from March to November 2016, in the Hospital General of Occidente in Jalisco, Mexico. A 12-lead electrocardiogram was performed at a speed of 25mm/s during the first 48h of life. The QT interval was measured in lead DII, and the QTc interval was calculated using the Bazett formula. Patients detected with QTc prolongation were assessed monthly with an ECG and echocardiogram. If they persisted with prolonged QTc interval, they were re-evaluated at 6 months with an ECG, 24h Holter, and electrocardiography study on parents and siblings. Those who persisted with prolonged QTc interval were evaluated with an ECG at 9 months.

Results: The study included 548 patients. The mean QTc interval at birth was 459 ms; during this period 33 patients has a QTc greated that 470 ms; which were evaluated monthly with a new electrocardiographic study, obtaining a mean QTc interal of 446 ms. At 6 months 16 patients were evaluated, with a mean QTc interval of 434ms. At 9 months, 6 patients were found to have a mean QTc interval of 438ms, and only 4 patients persisted with a prolonged QTc interval.

Conclusions: The QTc interval in our population is prolonged compared to other populations and with a gradual return to normal.