What are the diagnosis and management strategies for Acute Coronary Syndrome (ACS) with ST-Elevation Myocardial Infarction (STEMI)?

Diagnosis and Management of ACS STEMI

Primary PCI is the recommended reperfusion strategy for STEMI patients when it can be performed within 120 minutes of diagnosis; otherwise, immediate fibrinolysis should be initiated within 10 minutes of STEMI diagnosis. 1

Diagnosis of STEMI

• A 12-lead ECG should be performed and interpreted within 10 minutes of first medical contact to identify ST-segment elevation or equivalent 2, 3
• STEMI is diagnosed by persistent ST-segment elevation in at least two contiguous leads or new left bundle branch block with clinical symptoms of myocardial ischemia 1
• In some cases, patients may have coronary occlusion without characteristic ST elevation, presenting with bundle branch block, ventricular pacing, hyperacute T-waves, isolated ST-depression in anterior leads, or universal ST depression with ST-elevation in aVR 1
• Blood samples should be collected for high-sensitivity cardiac troponin measurement, but reperfusion decisions should not be delayed waiting for results 2, 4
• Echocardiography should be performed to assess left ventricular function and detect mechanical complications 1, 3

Immediate Management

• Time is critical - "time zero" in the reperfusion strategy clock begins at STEMI diagnosis 1
• Patients should be transferred directly to the catheterization laboratory, bypassing the emergency department 1, 3
• Continuous cardiac rhythm monitoring with defibrillator capacity should be initiated immediately 2, 3
• Supplemental oxygen should be administered only if oxygen saturation is <90% 1

Reperfusion Strategy

• Primary PCI is the preferred reperfusion strategy when it can be performed within 120 minutes of STEMI diagnosis 1
• If primary PCI cannot be performed within 120 minutes, fibrinolytic therapy should be initiated immediately (within 10 minutes of STEMI diagnosis) 1
• For patients receiving fibrinolysis, transfer to a PCI-capable center is indicated immediately after fibrinolysis 1
• Rescue PCI is indicated immediately when fibrinolysis has failed (<50% ST-segment resolution at 60-90 minutes) 1
• In patients with successful fibrinolysis, angiography and PCI of the infarct-related artery is recommended between 2-24 hours 1

Antithrombotic Therapy

For Primary PCI

• Aspirin (150-300mg loading dose) should be administered as soon as possible 1, 2
• A potent P2Y12 inhibitor (prasugrel or ticagrelor) should be administered before or at the time of PCI 1, 3
• Prasugrel is contraindicated in patients with prior stroke/TIA and generally not recommended in patients ≥75 years of age 5
• Unfractionated heparin is recommended as the standard anticoagulant 1, 3

For Fibrinolysis

• Aspirin (oral or IV) is indicated 1
• Clopidogrel is indicated in addition to aspirin 1
• Enoxaparin IV followed by subcutaneous administration is preferred over unfractionated heparin 1

Technical Aspects of Primary PCI

• Routine radial access is the standard of care during primary PCI 1, 3
• Drug-eluting stents are the standard of care 1, 3
• Routine thrombus aspiration or deferred stenting are contraindicated 1
• Treatment of severe non-infarct related artery stenosis should be considered before hospital discharge 1
• In cardiogenic shock, non-infarct related artery PCI should be considered during the index procedure 1

Post-Reperfusion Care

• Patients should be monitored for at least 24 hours after reperfusion therapy 1
• Dual antiplatelet therapy should be continued for 12 months 1, 3
• High-intensity statin therapy should be started as early as possible 2, 3
• Beta-blockers are indicated in patients with heart failure and/or left ventricular ejection fraction <40% 3
• ACE inhibitors should be started within 24 hours in patients with heart failure, LV systolic dysfunction, diabetes, or anterior infarct 3

Management of Complications

• For cardiogenic shock, emergency angiography and PCI are indicated 1, 3
• In cardiac arrest patients with ST-elevation on post-resuscitation ECG, primary PCI strategy should be followed 1
• In cases without ST-segment elevation on post-resuscitation ECG but with high suspicion of ongoing myocardial ischemia, urgent angiography should be performed within 2 hours 1

Special Considerations

• Women and men receive equal benefit from reperfusion and other STEMI-related therapies and should be managed equally 1
• Special attention to dose adjustment of pharmacological therapies is required in patients with renal insufficiency and/or the elderly 1
• For patients with MINOCA (Myocardial Infarction with Non-Obstructive Coronary Arteries), additional diagnostic tests should be performed to identify the etiology 1
• Patients with diabetes require additional attention to optimize outcomes 1

Common Pitfalls to Avoid

• Delaying ECG beyond 10 minutes of presentation can lead to missed diagnosis and delayed treatment 2
• Waiting for troponin results before initiating reperfusion therapy in patients with clear STEMI on ECG 2, 4
• Failing to recognize atypical presentations of ACS, particularly in women, elderly, and diabetic patients 2
• Delaying transfer to a PCI-capable center when fibrinolysis is the initial reperfusion strategy 1