The usefulness of electrocardiographic T axis for the diagnosis of acute myocardial ischemia

Ahn, Byung Chan; Shim, Jae Yoon; Kim, Jae Hoon; Yoo, Sun Mi; Cheong, Yoo Seok; Park, Eal Whan

Abstract

BACKGROUND
Electrocardiographic variables such as changes in the ST-T segment, and increased QT interval have been found to predict the occurrence of myocardial ischemia. But disadvantages of most of these variables have poor reproducibility and require analysis of all ECG leads. If electrocardiographic T axis properly predicts myocardial ischemia, it can be used as a useful marker for diagnosing myocardial ischemia in primary practice.
METHODS
We selected 147 persons, who visited the emergency room or an outpatient clinic because of chest pain, in whom coronary angiography was performod. We reviewed their medical records. Electrocardiographic T axis was classified as normal, borderline and abnormal T axis. We identified the relation between cardiovascular risk factors and electrocardiographic T axis, and also, the relation between ischemic electrocardiographic variables and T axis. We examined the relation between coronary angiographic results and electrocardiographic T axis.
RESULTS
The sensitivity and specificity of electrocardiographic T axis was 26.7% and 86.9%, respectively. The positive predictive value and negative predictive value was 81.8% and 35.1%, respectively. The proportion of hypertension was 41.2% in normal T axis group, 65.5% in borderline T axis group, and 34.4% in abnormal T axis group, which was statistically significant (P=0.032). The relation between coronary angiographic results and electrocardiographic T axis was not statistically significant. The subjects with abnormal T axis were associated with ST depression (P=0.016).
CONCLUSION
The T axis abnormality was not useful for screening myocardial ischemia, but it was useful to rule out other diseases due to its high specificity.