Overview
This lecture covers the essentials of acute coronary syndrome, including its causes, risk factors, diagnosis, clinical manifestations, initial management, and long-term care.
Acute Coronary Syndrome: Causes and Types
- Acute coronary syndrome (ACS) results from acute myocardial ischemia and can lead to myocardial infarction (MI) or death.
- Most ACS cases are due to plaque buildup in coronary arteries, causing angina that can progress to MI.
- Plaque rupture can cause complete (STEMI) or partial (NSTEMI, unstable angina) artery blockages.
- Other MI causes include coronary vasospasm (e.g., drug use), decreased oxygen supply, or increased oxygen demand.
Types and Clinical Presentation
- Stable angina: chest pain relieved by rest or nitroglycerin, typically after exertion.
- Unstable angina: chest pain unrelieved by rest/nitroglycerin, no EKG or biomarker evidence of MI; may lead to MI.
- NSTEMI: elevated cardiac biomarkers, no ST elevation on EKG; partial vessel blockage, nontransmural damage.
- STEMI: ST elevation in ≥2 EKG leads, complete vessel blockage, significant myocardial damage.
Risk Factors
- Non-modifiable: family history, older age, male sex, African-American, American Indian, or Hispanic ethnicity.
- Modifiable: hyperlipidemia, smoking, hypertension, obesity, sedentary lifestyle, stress.
Signs and Symptoms
- Main: chest pressure, heaviness, crushing pain.
- Others: fever, indigestion, anxiety, dizziness, pale/clammy skin, increased then decreased blood pressure (possible shock).
- Specific to women: upper back pain, nausea, weakness, fatigue.
Diagnostics
- Troponins (I, T): most important, rise within 3-6 hours after MI; serial measurements needed.
- CK-MB: rises with cardiac cell damage.
- Myoglobin: rapid rise but not cardiac specific.
- EKG: perform within 10 minutes; look for ST elevation in ≥2 leads, T-wave inversion, abnormal Q wave.
- Echocardiogram: assess for ischemia or reduced ejection fraction.
- Stress test: for selected patients.
EKG Changes
- Ischemia: ST depression, T-wave inversion.
- Injury/acute MI: ST elevation at J point (≥1 mm).
- Old infarct: abnormal Q wave without ST/T changes.
Initial Management
- "ROMAN" mnemonic: Rest, Oxygen, Morphine, Aspirin, Nitroglycerin.
- Continuous EKG, oxygen if SpO₂ <93%, two large-bore IVs, bed rest.
- Morphine if nitro fails or for anxiety (watch for hypotension, low respirations).
- Chewable aspirin (162-324 mg).
- Antiplatelets, anticoagulants, beta-blockers, statins, ACE inhibitors as indicated.
Advanced Treatment
- PCI (percutaneous coronary intervention): door-to-balloon ≤60 minutes preferred.
- Thrombolytics if PCI unavailable (within 30 min of arrival, symptoms <12 hr).
- Monitor for bleeding, arrhythmias post-thrombolysis.
Long-Term Management and Education
- Lifestyle: DASH/cardiac diet, smoking/alcohol cessation, exercise, cardiac rehab.
- Medication adherence is crucial; case management may assist with access.
- Monitor for statin and ACE inhibitor side effects.
- Emphasize gradual return to activity and avoiding exertion when symptomatic.
- Reduce anxiety and encourage long-term disease management.
Key Terms & Definitions
- Acute Coronary Syndrome (ACS) — Sudden decreased blood flow to the heart, risking infarction or death.
- Myocardial Infarction (MI) — Death of heart muscle tissue due to lack of blood supply.
- STEMI/NSTEMI — MI with (STEMI) or without (NSTEMI) ST elevation on EKG.
- Troponin — Cardiac protein released during myocardial damage.
- PCI — Procedure to open blocked coronary arteries.
Action Items / Next Steps
- Review cardiac emergency protocols (ROMAN mnemonic).
- Study the differences between STEMI, NSTEMI, and unstable angina.
- Be able to interpret basic EKG changes in ischemia and infarction.
- Read about the DASH and cardiac diet for patient education.