The purpose of the study is to evaluate the utility of Ischemia Modified Albumin (IMA) for risk stratification in patients presenting with chest discomfort and possible ischemic heart disease, and to evaluate the diagnostic and prognostic implication for IMA for major adverse cardiac events.

Inclusion Criteria:

• Patients with primary complaints of chest discomfort or patients with symptoms indicative of a moderate to high probability for unstable angina clinically indicated reason for evaluation for ACS in the Emergency Department meeting tyhe following inclusion criteria will be enrolled:
• Age >=21 years
• Presentation within two hours of relief of most recent episode of chest pain or presence of on-going symptoms suggestive of coronary ischemia, which should be at least 10 minutes in duration.
• Patients being evaluated for suspected ischemic signs and or symptoms (chest pain) at the time of presentation according to routine standard of care institutional chest pain protocol/pathway.

Exclusion Criteria:

• Administration of thrombolytic medication prior to first (presentation) blood draw
• Acute coronary syndrome (ACS) secondary to supply/demand inequity (i.e. known anemia, tachycardia, - defined as HR greater than 150 bpm, known sepsis, hypotension, defined as blood pressure < 90 mmHg).
• Established diagnosis of liver cirrhosis
• Other acute ischemic sources (ongoing severe claudication, mesenteric ischemia, acute TIA/CVA)
• Renal failure requiring dialysis
• Greater than 2 hours from relief of the most recent episode of chest pain or signs and symptoms suggestive of coronary ischemia.
• Chest pain following traumatic injury to the chest
• Evidence for sever systemic infection, manifesting as fever (temperature >100 degrees) and systolic blood pressure <100 mmHg
• Patients unwilling or unable to provide written consent, without available next of kin
• Cocaine-related chest pain
• Pregnancy
• Known diagnosis of active malignancy
• Acute Bowel Ischemia
• Severe peripheral vascular disease
• Acute brain ischemia

Patients who present in the emergency department at the listed institutions with suspected ischemic signs and or symptoms (chest pain) will be eligible for participation in the study as long as they meet inclusion and exclusion criteria and sign an informed consent.