Myocardial ischemia causes changes in the depolarization phase of the cardiac cycle, which can be quantified by analysis of high-frequency QRS components (HFQRS). We introduce a novel HFQRS analysis technology and evaluate its performance in monitoring transient ischemic episodes in patients hospitalized due to chest pain. Continuous monitoring by high-resolution 12-lead ECG was performed in 43 patients admitted to a chest pain unit, followed by cardiac imaging. Indices of HFQRS based on ischemia-specific morphological changes and conventional ST segment levels were extracted from signal-averaged ECG. HFQRS indices were positive for 5 of 10 patients that were diagnosed with coronary artery disease, while ST analysis was negative for all patients. The severity of the HFQRS indices was directly related to the likelihood of ischemic events. HFQRS is a promising technology for monitoring and early detection of acute coronary syndrome.