Prediction of QTc length as function of BMI: A clinical tool to establish arrhythmias risk in obesity

Abstract Among the electrocardiographic alterations used for stratifying the cardiovascular risk of life threatening arrhythmias (LFA) and sudden death (SD) there is the increment of the corrected QT(QTc). This increment is usually observable in obese patients (OP). Therefore, a study has been planned to investigate the possibility to predict QTc values in OP simply by detecting the best fitting regression method that represents the relationship between QTc and Body Mass Index (BMI). The study has been carried on 144 individuals classified as a function of their BMI in normoponderal subjects (NPS, No. 24; F/M=15/9; BMI=21.8± 1.7 kg/m(2)), Class I OP (No. 24; F/M=17/7; BMI=32.5± 1.1 kg/m(2)); Class II OP (No. 24; F/M=17/7; BMI=37.7± 1.5 kg/m(2)). Class IIIa (No. 24, F/M=15/9; BMI=44.4± 27 kg/m(2)), Class IIIb (No. 24; F/M=14/10; BMI 54.3± 2.7 kg/m(2)); Class IIIc (No. 24; F/M=14/10; BMI=63.3± 4.5 kg/m(2)). Both linear and non-linear fitting modes have been tested. While the BMI progressively increases in classified OP, the QTc shows an intergroup difference that is not only not constant but also declining in Class IIIc obesity. The optimal regressive model was found to be the following fourth order degree polynomial: QTc=317,15+(7,47xBMI)+(-0,28*BMI(2))+(0,005xBMI(3))+ (-0,00003xBMI(4)). By entering the BMI of a given OP into the above-cited formula, the QTc can be easily predicted and compared to that of NPS. Importantly, to have the possibility for a pre-electrocardiographic estimation of QTc allows all the medical and paramedical personnel, involved in the multidisciplinary treatment of obesity, to immediately establish the cardiovascular risk in the OP under observation.