Extracardiac factors influencing left ventricular hypertrophy classification models

Extracardiac factors are known to influence electrocardiographic (ECG) features used in left ventricular hypertrophy (LVH) classification criteria. It is generally assumed that ECG amplitudes decrease with age and obesity. The authors examined the association between anthropometric variables and the standard 12-lead resting ECG of white, black and Hispanic men and women and found that, contrary to the expectations, many ECG amplitudes such as RaVL+SV3 increased with increasing body mass index (BMI) and changed little with age. As expected, obesity was associated with leftward shift of QRS axis. However, the leftward shift of about 8 degrees per decade of age was equally pronounced in overweight and normal-weight women and men. The apparent strong influence of chest size and configuration on ECG amplitudes is largely due to variations in body weight and heart size. Smaller QRS amplitudes in left lateral chest leads in women appear partially to be associated with the attenuating effect of the breast tissue. It is concluded that chest size and configuration, and body weight have a strong influence on ECG amplitudes used in LVH criteria and that this influence differs from lead to lead and the interactions are complex. Extracardiac anthropometric factors, age, gender, and ethnic differences need to be properly considered in order to improve LVH criteria and ECG models for left ventricular mass estimation.<>