Frontal QRS-T angle and World Health Organization classification for body mass index

The frontal QRS-T angle, defined as the absolute value of the difference between QRS axis and T-wave axis on 12‑lead electrocardiogram (ECG), is the difference in orientation between ventricular depolarization and repolarization. We tested the hypothesis that QRS-T angle is affected by obesity.

A total of 177 patients undergoing both ECG and echocardiography within one month were recruited from outpatient clinic. Using the World Health Organization (WHO) classification of body mass index (BMI), the patients were classified into the four groups: underweight (<18.5 kg/m², n = 25), normal weight (18.5-24.9 kg/m², n = 79), overweight (25-29.9 kg/m², n = 38) and obese (≥30 kg/m², n = 35).

Obese patients were significantly younger than those in other groups. As for echocardiographic variables, left ventricular internal dimension and left ventricular mass (LVM) increased with increased WHO classification of BMI. QRS axis and T-wave axis decreased with increased WHO classification of BMI, whereas QRS-T angle increased. Multivariate linear regression analysis showed that BMI (β = 0.23, p = 0.01) and LVM (β = 0.19, p = 0.046) were independent determinants of QRS-T angle.

Our results suggest that BMI is an independent determinant of QRS-T angle.