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P01.003 Acute coronary syndromes
Acute Coronary Syndromes (ACS) encompasses a range of conditions associated with sudden, reduced blood flow to the heart. This includes unstable angina, non-ST-elevation myocardial infarction (NSTEMI), and ST-elevation myocardial infarction (STEMI). Understanding the differences, diagnosis, and management of these conditions is crucial for the PLAB exam.
Types of Acute Coronary Syndromes
| Type | Description | ECG Findings | Biomarkers |
|---|---|---|---|
| Unstable Angina | Reduced blood flow causing chest pain, no myocardial damage | Normal or non-specific changes | Normal |
| NSTEMI | Myocardial infarction without ST elevation | ST depression, T wave inversion | Elevated (Troponin, CK-MB) |
| STEMI | Myocardial infarction with ST elevation | ST elevation in contiguous leads | Elevated (Troponin, CK-MB) |
Pathophysiology
- Atherosclerosis: Plaque buildup in coronary arteries leads to reduced blood flow.
- Plaque Rupture: This leads to thrombus formation and acute obstruction of blood flow.
- Myocardial Ischemia/Infarction: Insufficient oxygen supply to the heart muscle.
Clinical Presentation
- Chest Pain: Central, crushing chest pain radiating to the left arm, neck, or jaw.
- Associated Symptoms: Shortness of breath, sweating, nausea, dizziness.
- Atypical Symptoms: In elderly, diabetic patients, and women (e.g., epigastric pain, fatigue).
Diagnosis
- Clinical History and Examination
- ECG
- Immediate ECG for any suspected ACS.
- Repeat ECGs as necessary.
- Biomarkers
- Cardiac troponins (T and I) are the gold standard.
- CK-MB (Creatine Kinase-MB) for additional confirmation.
- Imaging
- Echocardiography to assess wall motion abnormalities.
- Coronary angiography for definitive diagnosis and intervention.
Management
| Phase | Treatment |
|---|---|
| Initial Management | – Oxygen if hypoxic<br>- Nitrates (GTN)<br>- Aspirin<br>- Morphine for pain relief |
| Antiplatelet Therapy | – Dual antiplatelet therapy (DAPT): Aspirin + P2Y12 inhibitor (e.g., clopidogrel) |
| Anticoagulation | – Heparin or LMWH (Low Molecular Weight Heparin) |
| Reperfusion Therapy | – STEMI: Primary PCI (Percutaneous Coronary Intervention) within 90 minutes or thrombolysis if PCI not available.<br>- NSTEMI/Unstable Angina: Risk stratify using scores like GRACE to decide on early invasive vs. conservative management. |
| Beta-blockers | – To reduce myocardial oxygen demand |
| Statins | – High-intensity statins for secondary prevention |
| ACE Inhibitors | – For patients with left ventricular dysfunction, hypertension, or diabetes |
Secondary Prevention
- Lifestyle Modifications
- Smoking cessation, dietary changes, exercise.
- Medications
- Aspirin, P2Y12 inhibitors, beta-blockers, ACE inhibitors, statins.
- Cardiac Rehabilitation
- Structured programs to aid recovery and prevent recurrence.
Points to Remember
- Recognize symptoms early and perform prompt ECG.
- Understand the differences between unstable angina, NSTEMI, and STEMI.
- Familiarize with the initial management protocols, including MONA (Morphine, Oxygen, Nitrates, Aspirin).
- Know the indications and timing for reperfusion therapy.
- Emphasize secondary prevention to reduce the risk of future events.