Overview of Acute Coronary Syndrome

Dec 15, 2024

Acute Coronary Syndrome Lecture Notes

Introduction

  • Topics Covered: Acute coronary syndrome, unstable angina, STEMI, NSTEMI, Dressler syndrome, cocaine-induced MI.
  • Purpose: Key points for PANCE exam preparation.

Acute Coronary Syndrome (ACS)

  • ACS refers to suspicion or confirmed acute myocardial ischemia or infarction.
  • Often due to plaque rupture leading to secondary artery thrombosis.

Types of ACS

  • Unstable Angina: Partial occlusion of coronary arteries.
  • NSTEMI (Non-ST Elevation Myocardial Infarction): Positive cardiac enzymes without ST elevation.
  • STEMI (ST Elevation Myocardial Infarction): Complete 100% occlusion and ST elevation on EKG.

Clinical Manifestations of ACS

  • Pain Characteristics:
    • Not relieved with rest or nitroglycerin.
    • Lasts over 30 minutes.
    • Can radiate to the left arm, jaw, back.
    • Non-positional, non-pluritic, and non-reproducible.
  • Sympathetic Activation: Tachycardia, diaphoresis, nausea, vomiting.
  • Atypical Presentations: Syncopal episodes, weakness, palpitations, dyspnea, or epigastric pain especially in women, elderly, and diabetics.

Diagnosing ACS

  • EKG:
    • Unstable Angina: No ST elevation, possible T-wave inversion, or ST depression.
    • NSTEMI: Similar EKG to unstable angina but with positive cardiac enzymes.
    • STEMI: ST elevation in two or more contiguous leads.
  • Cardiac Biomarkers:
    • Troponin: Most sensitive and specific, rises 4 hours post-MI, stays elevated up to 10 days.
    • CK-MB: Used if troponin is unavailable or in cases of reinfarction.
    • Myoglobin: Peaks quickly (2 hours), not commonly used.

Treatment of ACS

  • Initial Treatment (MOAN):
    • Morphine: Only if pain is unmanageable.
    • Oxygen: If SpO2 <90%.
    • Aspirin: 325 mg chew and swallow upon arrival.
    • Nitrates: Avoid if patient is hypotensive, has right ventricular MI, or has taken PDE5 inhibitors.
  • Long-term Management (BASH):
    • Beta blockers: unless contraindicated.
    • ACE inhibitors: Improves mortality, started within 24-48 hours.
    • Statins: High intensity for patients with CAD.
    • Heparin or other antithrombotics.

Reperfusion Therapy

  • Percutaneous Coronary Intervention (PCI): Preferred, done within 90 minutes.
  • Thrombolytics (e.g., TPA): Used if PCI is not available within 90 minutes.

Miscellaneous Topics

  • Cocaine-Induced MI:
    • Presentation similar to MI due to coronary artery vasospasm.
    • Treatment: Calcium channel blockers, avoid non-selective beta blockers.
  • Dressler Syndrome (Post-MI Pericarditis):
    • Treatment with aspirin or colchicine.
  • Right Ventricular Infarction:
    • Clinical triad: Increased JVP, clear lungs, Kussmaul sign.
    • Avoid nitrates and morphine.

Important EKG Leads for MI

  • Inferior Wall MI: Leads II, III, aVF.
  • Anterior Wall MI: Leads V2-V5.
  • Septal Wall MI: Leads V1-V2.
  • Lateral Wall MI: Leads I, aVL, V5-V6.
  • Posterior Wall MI: ST depression in V1-V2, confirmed with posterior leads V7-V9.

Review Questions

  1. Atypical ACS Presentation Populations: Women, elderly, diabetics.
  2. Cocaine-Induced MI Treatment: Calcium channel blockers.
  3. Inferior Wall MI EKG Leads: II, III, aVF.
  4. Fastest Peaking Cardiac Biomarker: Myoglobin.
  5. Post-MI Pericarditis: Dressler syndrome.

This lecture provides a comprehensive overview of acute coronary syndrome, its types, clinical manifestations, diagnosis, and treatment. Remember, EKG and troponins are key for diagnosis. Treatment involves a systematic approach using MOAN and BASH mnemonics. Reperfusion therapy is critical for restoring blood flow in patients with acute MI.