Makindo Medical Notes

Management of STEMI (Chest Pain + ECG)

Key Point: Immediate referral to Cardiology for Primary Percutaneous Intervention (Primary PCI) is essential; target door-to-balloon time should be within 60 minutes. Establish an IV line, draw blood samples for full blood count, U&Es, glucose, troponin, and lipids. A chest X-ray may be requested but should not delay initial therapy.

Aetiology

• Usually caused by a completely occluded coronary artery, typically due to a ruptured atherosclerotic plaque with subsequent thrombus formation.
• The extent of myocardial damage depends on the artery involved and the location of the occlusion (proximal occlusions generally result in greater myocardial damage).
• Rapid treatment is critical to limit myocardial damage and improve survival rates.

Clinical Presentation

• Classic symptoms include central or retrosternal chest pain/tightness, often described as a pressure or heaviness.
• Pain may radiate to the neck, shoulders, jaw, or left arm.
• Associated symptoms: Dyspnoea, nausea, vomiting, sweating (diaphoresis), and a sense of impending doom.
• Occasionally, presentations can be atypical, especially in the elderly, diabetics, or women, such as syncope, falls, or even isolated dyspnoea.
• Signs may include hypotension, tachycardia or bradycardia, pulmonary oedema, or new heart sounds (e.g., S4, murmurs of mitral regurgitation).

ECG Criteria (ST-Elevation Myocardial Infarction)

• ST elevation in two contiguous leads:
  • >2 mm in leads V2-V3 (men) or >1.5 mm in women.
  • >1 mm in other contiguous chest or limb leads.
• New or presumed new left bundle branch block (LBBB) in a symptomatic patient.
• Isolated posterior MI: ST depression and tall R waves in leads V1-V3, confirmed by ST elevation in posterior leads V7-V9.
• Right ventricular MI: ST elevation in V4R and other right-sided chest leads.

Troponin

• Cardiac troponin levels will be elevated within 3-12 hours after the onset of myocardial damage and peak at 24-48 hours. Repeat testing at 3 hours is often used for diagnosis.
• If there is clinical uncertainty and troponin is unavailable, a bedside echocardiogram may show regional wall motion abnormalities corresponding to the affected territory.

Immediate Actions

• NB: MI can be silent, especially in elderly, diabetic, or female patients. Ensure defibrillator availability.
• Assess for ABCs (Airway, Breathing, Circulation) and monitor vital signs (NEWS/MEWS). Place the patient on continuous cardiac monitoring.
• Establish IV access and draw blood for FBC, U&E, LFTs, Troponin, and D-dimer if PE or dissection is suspected.
• Admit to the Cardiac Care Unit (CCU) or other monitored bed.

Medications (MONA + P2Y12 + Anticoagulation)

• Morphine 2.5-5 mg IV (may repeat) for pain control; administer with antiemetic (e.g., Metoclopramide 10 mg IV).
• Oxygen to maintain SpO₂ > 94% (caution in COPD patients).
• Nitrates (GTN spray or tablet, or IV infusion if SBP > 110 mmHg) for chest pain.
• Aspirin 300 mg PO stat (US dose: ASA 162-325 mg PO/PR).
• Initiate a P2Y12 antagonist:
  • Clopidogrel 300-600 mg PO (if allergy or contraindications to others).
  • Ticagrelor 180 mg PO stat (preferred in most cases).
  • Prasugrel 60 mg PO (use in patients < 75 years and without a history of stroke/TIA).
• Anticoagulation:
  • Fondaparinux 2.5 mg SC once daily (if PCI is delayed).
  • Unfractionated heparin (UFH) if proceeding directly to PCI.

Reperfusion Therapy

• Primary PCI: Indicated for patients presenting within 12 hours of symptom onset. Aim for a door-to-balloon time < 90 minutes.
• Transfer to a PCI-capable center immediately if the patient can be taken to the catheter lab within 120 minutes.
• PCI can be done through a radial or femoral approach, with radial access becoming more common due to fewer complications.
• GPIIb/IIIa inhibitors (e.g., Abciximab) may be considered during PCI for high thrombus burden.
• Thrombolysis: Consider if PCI cannot be performed within 120 minutes.
  • Use Tenecteplase, Alteplase, or Streptokinase, depending on availability and patient factors.
  • Absolute contraindications: History of hemorrhagic stroke, active bleeding, recent major trauma or surgery, aortic dissection.
  • Relative contraindications: Recent TIA, anticoagulant therapy, pregnancy, uncontrolled hypertension.

Post-PCI Management

• High-dose statin (e.g., Atorvastatin 80 mg PO nocte) to stabilize plaques and lower LDL levels.
• Start ACE inhibitors (e.g., Ramipril) in patients with heart failure, LV dysfunction, or hypertension.
• Aldosterone antagonists (e.g., Eplerenone) for patients with LV dysfunction (EF < 40%) and heart failure or diabetes.
• Initiate beta-blockers (e.g., Metoprolol) if no contraindications (e.g., asthma or heart failure with low-output state).
• Continue dual antiplatelet therapy (DAPT) for 12 months post-stenting to reduce the risk of stent thrombosis.
• Monitor for complications such as arrhythmias, heart failure, or reinfarction.

Long-term Management and Lifestyle Modifications

• Encourage lifestyle changes: Smoking cessation, a heart-healthy diet (Mediterranean diet), regular physical activity, and weight management.
• Refer to cardiac rehabilitation programs for structured exercise and education on lifestyle changes.
• Manage comorbidities such as diabetes, hypertension, and hyperlipidemia aggressively to prevent further cardiovascular events.
• Discuss the risks and benefits of anticoagulation in patients with atrial fibrillation or LV thrombus, using risk scores such as CHA₂DS₂-VASc.

Follow-Up and Secondary Prevention

• Arrange follow-up with a cardiologist within 2-6 weeks post-discharge.
• Monitor for adherence to medications and adjust doses as needed based on renal function and tolerance.
• Repeat echocardiography to assess LV function and monitor for complications like heart failure or LV aneurysm.

References

• NICE Guidelines for Acute Coronary Syndromes
• European Society of Cardiology Guidelines
• American Heart Association (AHA) Guidelines