The primary objective of this study is to characterize the morphological patterns of high frequency QRS components (HFQRS) in patients with acute myocardial infarction (AMI), including STEMI and NSTEMI, compared to patients without AMI.

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.

Inclusion Criteria:

• Age > 40 years (men and women)
• Time from onset of chest pain ≤ 12h
• AMI confirmed by biomarkers
• Clinical or electrocardiographic evidence of ischemia during recording
• Signed an informed consent

Exclusion Criteria:

• Prior MI
• Prior CABG
• pre-excitation syndrome (e.g. WP)
• Atrial Fibrillation or significant ventricular arrhythmia
• BBB, intraventricular conduction delay or QRS duration > 120 ms
• Implanted pacemaker or defibrillator
• Left-ventricular hypertrophy

Patients presenting with confirmed AMI in the intensive cardiac care unit (ICCU) of Soroka Medical Center (Beer Sheva, Israel), who are expected to undergo percutaneous coronary intervention (PCI) will be asked to participate in the study. These include both ST-elevation MI (STEMI) and non ST-elevation MI (NSTEMI) patients, with positive biomarkers and clear ongoing electrocardiographic or clinical evidence of ischemia.