T Vector and Loop Characteristics Improve Detection of Myocardial Injury After Infarction
Hans Reiner Figulla,
Electrocardiography (ECG) is widely used to detect myocardial injury. ECG recordings after subendocardial, non-ST-elevation myocardial infarction (MI) may lack striking infarct patterns. A vectorcardiogram (VCG) of the T wave is a three-dimensional characterization of the ventricular repolarization and identifies abnormalities at an advanced level of analysis, which would normally be done manually from conventional ECG. Several parameters describing T vector loop morphology and T vector spatial orientation are examined with regard to their suitability for late MI detection. The discriminatory performance of VCG analysis is compared to that of conventional ECG analysis in identifying post-MI patients. T vector and T loop parameters as well as infarct indicators of the ECG recordings were calculated for 114 subjects: 59 patients (42 males; mean age: 54 years) 15 days after MI (11.9 ± 6.9 d) and 55 healthy controls (27 males; mean age: 49 years). ECG infarct indicators correctly identified 75.2 % of patients, while T vector and loop parameters correctly identified 83.2 % of patients. Discrimination analysis revealed a sensitivity of 66.7 % and a specificity of 77.4 % for conventional ECG, and a sensitivity of 71.7 % and a specificity of 88.7 % for the VCG parameters. T vector and loop characteristics were superior to conventional ECG in separating patients from controls. T vector ECG can improve the detection of myocardial injury and is applicable to the analysis of cardiac repolarization.