What is the diagnosis and management for a patient with acute inferior STEMI (ST-elevation myocardial infarction) presenting with chest pain and diaphoresis (profuse sweating)?

From the Guidelines

The diagnosis for a patient with acute inferior STEMI presenting with chest pain and diaphoresis is confirmed by an electrocardiogram (ECG) showing ST-segment elevation in the inferior leads, and management involves immediate reperfusion therapy, preferably primary percutaneous coronary intervention (PCI), as recommended by the American College of Cardiology/American Heart Association (ACCF/AHA) guidelines 1.

Key Management Strategies

• Reperfusion therapy should be administered to all eligible patients with STEMI within 12 hours of symptom onset, with primary PCI being the preferred method when it can be performed in a timely fashion by experienced operators 1.
• Primary PCI should be performed in patients with STEMI and ischemic symptoms of less than 12 hours’ duration, with a goal of achieving a door-to-device time of 90 minutes or less 1.
• In cases where primary PCI cannot be performed within 120 minutes, fibrinolytic therapy may be considered, especially if the patient presents within 12 hours of symptom onset and there are no contraindications 1.
• Adenosine diphosphate receptor antagonists and unfractionated heparin (UFH) may be given to patients with suspected STEMI who are planned for primary PCI, either prehospital or in-hospital 1.

Important Considerations

• Time is muscle: every effort should be made to provide reperfusion therapy as rapidly as possible to minimize cardiac damage and improve outcomes 1.
• Individualized approach: the decision between primary PCI and fibrinolysis should be based on individual patient factors, including time from symptom onset, anticipated delay to PCI, and relative contraindications to fibrinolysis 1.
• Systems of care: establishing efficient systems of care, including rapid transportation to PCI-capable hospitals and timely activation of the catheterization laboratory, can significantly improve STEMI outcomes 1.

From the Research

Diagnosis of Acute Inferior STEMI

• The diagnosis of acute inferior STEMI is typically made using electrocardiography (ECG), which can distinguish between STEMI and non-ST-segment elevation ACS (NSTE-ACS) 2.
• ECG should be performed immediately (within 10 minutes of presentation) for patients presenting with possible ACS 2.
• STEMI is caused by complete coronary artery occlusion and accounts for approximately 30% of ACS 2.

Management of Acute Inferior STEMI

• Rapid reperfusion with primary percutaneous coronary intervention (PCI) within 120 minutes reduces mortality from 9% to 7% 2.
• If PCI within 120 minutes is not possible, fibrinolytic therapy with alteplase, reteplase, or tenecteplase at full dose should be administered for patients younger than 75 years without contraindications and at half dose for patients 75 years or older (or streptokinase at full dose if cost is a consideration), followed by transfer to a facility with the goal of PCI within the next 24 hours 2.
• Prehospital diagnosis of patients with STEMI is performed to save time and make primary percutaneous coronary intervention (PPCI) available to the majority of patients 3.
• PPCI should be performed within 120 min of first medical contact for patients with STEMI 3.

Consideration of Other Diagnoses

• Type A aortic dissection with concurrent STEMI is relatively rare, but can be potentially fatal and easily misdiagnosed as STEMI alone 4.
• Misdiagnosis of Type A aortic dissection with STEMI can lead to inappropriate administration of anticoagulant and thrombolytic therapy and delayed surgical repair of the aorta 4.
• Atypical ECG patterns, known as "STEMI equivalents", are present in 10% to 25% of patients with ongoing myocardial ischemia in need of urgent primary percutaneous coronary intervention 5.
• Prompt recognition of "STEMI equivalent" ECG patterns is crucial for every physician or paramedic dealing with acute coronary syndrome patients in the emergency department or the prehospital setting, as misinterpretation of those high risk presentations can lead to reperfusion delays and worse outcomes 5.