Abstract 5694: Interpretation of the Spatial QRS-T Angle: Normal Limits in Healthy Subjects and Implications for Risk Stratification
Introduction - In healthy individuals, the QRS and T axes have a similar orientation, resulting in a small spatial QRS-T angle (spatial angle). It is known that a wide spatial angle, typically wider than 105°, is associated with the presence of cardiac disease and increased cardiac mortality. Normal variations of the spatial angle and the influence of gender are currently unknown. Therefore we determined normal limits of the spatial angle in the light of current risk stratification criteria and we analyzed differences between males and females.
Methods -Normal ECGs of 660 young, healthy subjects aged 18–29 yrs were included in the analysis (female/male: 449/211). The spatial angle was calculated from the standard ECG with a dedicated computer program. We analyzed male/female differences and determined normal limits of the spatial angle defined as the 2nd to 98th percentiles of observed values.
Results -In females, the spatial angle was significantly sharper (66 ±23° vs. 80 ±24°, P<0.001) than in males. Normal limits ranged from 20°–116° in females and from 30°–130° in males (figure 1⇓). Interestingly, 3.1% (n=14) of the females and 13.3% (n=28) of the males had a spatial angle within normal limits, but wider than 105°, which is currently considered a high risk category, see figure⇓.
Conclusion - In a population of healthy young subjects, the spatial angle has a wide range of normal limits and part of what is now considered a high risk category falls within the upper limits of normal. Moreover, there is a significant difference between males and females and interpretation should be done taking gender into account.