Feasibility of High Frequency QRS Analysis in Patients With Acute Myocardial Infarction

Chest pain is one of the leading reasons of hospital emergency department (ED) visits worldwide. In the US, approximately 6 million people annually undergo evaluation in the ED for acute chest pain. Despite the wealth of knowledge available about acute coronary syndrome (ACS), this condition continues to be among the most difficult to predict or diagnose. Misdiagnoses may lead to discharge of patients with ACS, who should have been admitted as well as costly unnecessary hospitalizations of patients who do not have ACS.

More than 2/3 of the patients with ACS have unstable angina (UA) or non-ST-elevation myocardial infarction (NSTEMI). Conventional ECG has low sensitivity of less than 50% in diagnosing these conditions. As the initial ECG in the ED is often non-diagnostic in ACS patients, the diagnosis of ST-elevation myocardial infarction (STEMI) during its early stages may also be difficult.

Analysis of high-frequency QRS components (HFQRS), which quantifies changes in the depolarization phase of the cardiac cycle, has been previously reported to be a sensitive method for detection of demand ischemia. Preliminary studies have shown that HFQRS-derived indices can also identify supply ischemia caused by prolonged balloon occlusion, and transient ischemic episodes in patients with chest pain.