Diagnostic Approach to Suspected Myocardial Infarction

Initial Evaluation

The European Society of Cardiology recommends obtaining cardiac troponin, 12-lead ECG, complete blood count, electrolytes, creatinine with renal function estimation, lipid profile including LDL-C, and glycemic status for patients with suspected heart attack 1, 2
Cardiac troponin using high-sensitivity or ultrasensitive assays should be obtained immediately to rule out acute myocardial injury 1, 2, 3
A 12-lead ECG should be performed to differentiate ST-elevation MI from non-ST-elevation presentations 4, 5
Complete blood count, including hemoglobin, should be obtained to detect anemia 1, 2
Electrolytes should be measured to identify metabolic derangements affecting management 1, 2
Creatinine with estimated glomerular filtration rate should be obtained as renal dysfunction increases CAD likelihood and affects prognosis 1, 2
Lipid profile, including LDL-C, should be obtained for cardiovascular risk assessment 1, 2
Glycemic status with HbA1c and/or fasting plasma glucose should be assessed since hypoglycemia can mimic MI and hyperglycemia worsens outcomes 1, 2

Patients with positive cardiac markers, new ST-segment deviations, ongoing chest pain, or hemodynamic abnormalities require hospital admission and aggressive management 4, 6
Patients with negative initial troponin, normal or non-diagnostic ECG, and resolved symptoms can undergo a 6-12 hour observation period with repeat troponin measurement 4, 6

The American College of Cardiology recommends immediate medical therapy, including aspirin, clopidogrel, low-molecular-weight heparin or unfractionated heparin, beta-blocker therapy, and nitrates for confirmed acute coronary syndrome 4, 7
Patients with persistent ST-segment elevation require immediate reperfusion therapy, with primary PCI preferred if available within guideline-mandated times, otherwise thrombolysis 4, 5

Thyroid function should be assessed at least once in patients with suspected chronic coronary syndrome, as hyperthyroidism can cause or exacerbate ischemia 1, 2
High-sensitivity C-reactive protein and/or fibrinogen plasma levels can be measured for additional prognostic information 1

Emergency echocardiography is recommended for evaluation of acute chest pain with non-diagnostic ECG and cardiac enzymes, patients with chest pain and hemodynamic instability, detection of mechanical complications, and assessment of left ventricular function 8