Study of cardiac repolarization during Oral Glucose Tolerance Test in metabolic syndrome patients

QT interval could be relevant for cardiopathy assessment in metabolic syndrome (MS) because of the increased difficulty the cells have to metabolize glucose, thus possibly prolonging QT intervals. The aim of this paper is to explore whether QT interval is altered in MS patients during the Oral Glucose Tolerance Test (OGTT). This database includes 10 healthy subjects and 15 MS patients undergoing OGTT. The ECG recordings were performed at sampling frequency of 1000 Hz, 16 bit resolution and 12-lead records. Each data set includes: 15 minutes ECG signal acquisition before the OGTT and before each blood samples extraction (30, 60, 90, 120 minutes). The wavelet transform method was used for delineating the ECG in this work. In order to find the end of T-wave, an alternative to threshold methods was used. This variation finds the extreme on the third derivative, which first appears ahead of the local maxima of a T-wave. The mean and the standard deviation (STD) of all QTc were calculated in each record. It was found a slight enlargement of the QT interval in MS respect to healthy subjects, however the difference doesn't seem to be of statistical significance. Yet, MS patients show a significant decrease in their STD respect healthy subjects.