Objectives: First derivative electrocardiography (FDECG) records the slope of the wave of the standard 12-lead electrocardiography (ECG) and enables quantification of ECG-T wave symmetry. This study investigated the usefulness of FDECG to diagnose effort angina pectoris in patients with chest pain.
Methods: All 62 patients who visited our hospital with exertional chest pain underwent FDECG at rest, and exercise electrocardiography or stress thallium scintigraphy. Patients with possible ischemic change underwent coronary angiography, and those with significant coronary artery stenosis (> or = 75% reduction) were classified as the angina pectoris group (23 subjects). The other patients (without ischemic change or without significant coronary artery stenosis) formed the non-angina pectoris group (39 subjects). The FDECG is a simple differential wave with two peaks. The first peak of the FDECG-T wave designated as the T1 wave and the second peak as the T2 wave. The heights (the T1 and T2 wave amplitude) and the T2/T1 ratio (T2 wave heights/T1 wave heights) were calculated in the two groups.
Results: The T2/T1 ratios in leads I, V3, V4, V5 and V6 were significantly (I, V3, V4: p < 0.01, V5: p < 0.0001, V6: p < 0.001) decreased in the angina pectoris group. Using the criterion of a T2/T1 ratio at the V5 lead of less than 1.30, FDECG could detect effort angina pectoris patients with 65% in sensitivity, 74% specificity and 71% accuracy.
Conclusions: ECG-T waves in the angina pectoris group were symmetrical. T2/T1 ratio of the FDECG-T wave is a useful index to diagnose effort angina pectoris at rest.