Influence of gender and malnutrition on QT dispersion in a north-Malagasy children population

Abstract

Children malnutrition involves simultaneous deficiency of nutrients, leading to cardiac morphological and functional alterations. In this complex condition repolarization abnormalities can evolve. Also sexual dimorphism is a well-established phenomenon, but its influence on ventricular repolarization varies tremendously among races. No data are available about African children, so the aim of our work was to study the correlation between malnourishment and electrocardiographic repolarization parameters, and evaluating the sex influence. 307 children (mean age 7,6±3 years old) were consecutively enrolled in the north of Madagascar. The QT interval was measured and corrected (QTc) following the Bazett formula (QT/√RR). QT dispersion (QTcd) was defined as the difference between maximum and minimum QTc. Malnutrition was defined in relation to age and sex specific BMI values. Grade mild, moderate and severe were defined as the value to pass through BMI of 16, 17 and 18,5 at the age of 18. 126 children (41%) were malnourished, 42 (13%) with mild, 61 (20%) moderate and 23 (7%) with a severe grade. No differences were found between normal weight and malnourished regarding the gender, age, height or heart rate. They had similar QT and QTc intervals (respectively 362,4±36 msec vs 365,1±47 msec for QT, p=0.59 and 476,9±43 msec vs 470±53 msec for QTc, p=0.70). QTcd was statistically higher in malnourished children (53,2±16 msec vs 44,4±15 msec, p<0.001). QTcd progressively increased from normal weight to severe malnutrition (p<0.001). At the multivariate analysis, independently from sex category, children with moderate [C.I. 3.94-13.1, p<0.001] and severe [C.I. 8.38-22.0, p<0.001] malnutrition had an higher risk to have an higher QTcd]. 146 children (48%) were male. Prolonged QTcd was found more frequently in male children (58% vs 44%, p=0.04), showing also longer QTc and QTcd (respectively 475,8±52 msec vs 462,3±42 msec, p=0.01; and 50,1±16 msec vs 46,2±16 msec, p=0.03). At the multivariate analysis, males had an higher risk [C.I. 0.28-7.35, p=0.03] to have higher QTc dispersion with respect to female children, independently to the nutrition state. Moderate to severe malnourishment and male sex independently influence ventricular repolarization, with higher QTc dispersion times and eventually higher risk of future arrhythmic complications. In these children, precaution must be taken with intensive correction of malnutrition and a strict ECG follow-up.