Acute Myocardial Infarction

Myocardial infarction (MI) is considered part of a spectrum referred to as acute coronary syndrome (ACS). The ACS continuum consists of unstable angina, non-ST-segment elevation myocardial infarction (NSTEMI) and ST-segment elevation myocardial infarction (STEMI). Without immediate reperfusion therapy, most people with STEMI develop Q waves, reflecting irreversible damage and death in part of the myocardium.

Diagnosis of whether the person is having a STEMI or NSTEMI is vital because the therapy differs for each of the types.
A suggested focus of the emergency department to assist in diagnosis is;
  • Identification of patients with STEMI. An ECG should be performed and shown to an experienced emergency medicinal physician within 10 minutes of arrival.
  • If STEMI is present, the decision as to whether the patient will be treated with thrombolysis or primary PCI should be made within the next 10 minutes.
  • If STEMI is not present, then the diagnostic review should proceed looking for unstable angina or NSTEMI and for alternative diagnoses. Confirmation of the diagnosis of NSTEMI requires waiting for the results of cardiac markers.
  • In the case of unstable angina, diagnosis may await further diagnostic studies. Although patients presenting with no ST-segment elevation are not candidates for immediate thrombolytics, they should receive anti-ischaemic therapy and may be candidates for PCI urgently or during admission.

Rapid diagnosis and early risk stratification of patients presenting with acute chest pain are important to identify patients in whom early interventions can improve outcome. The management of AMI is therefore well suited to a care bundle approach as delays in treatment affect survival in patients with AMI.