High fidelity ECG in the diagnosis of occult coronary artery disease: a study of patients with normal conventional ECG.

High fidelity (HF) electrocardiography (ECGY) was performed on four groups of patients with a normal resting electrocardiogram (ECG). Two groups (A and B) consisted of normal subjects over or under the age of 40, while the other two groups of patients (C and D) underwent coronary arteriography because of chest pain. HR ECG components within the initial portion of the QRS complex were significantly more common among patients with advanced coronary disease. The difference between the normal groups and the group with documented coronary artery disease (CAD) became more significant when the number of leads showing the HF ECG components was counted. Precordial leads were more sensitive in predicting the presence or absence of CAD than limb leads. HF ECG components in the terminal portion of the QRS complex did not differentiate between normals and patients with coronary artery disease, unless the number of leads showing these HF ECG components was considered. It seems that abnormal HF ECG components can point to minor areas of fibrosis caused by coronary artery disease even if the resting conventional ECG is normal.