Acute Coronary Syndromes - NREMT AEMT Level

1. What does the term acute coronary syndrome (ACS) refer to in prehospital care?

   Myocardial ischemia spectrum: unstable angina, NSTEMI, STEMI. ACS encompasses a continuum of myocardial ischemia conditions requiring prompt prehospital recognition and intervention to prevent progression to infarction.

2. Which radiation pattern is classically associated with ACS chest pain?

   Radiation to left arm, both arms, neck, jaw, or back. Pain radiation follows dermatomal patterns innervated by cardiac sympathetic nerves.

3. What is the standard adult aspirin dose for suspected ACS if not already taken and no contraindication?

   Chew $160$ to $325$ mg aspirin. Aspirin inhibits platelet aggregation, reducing thrombus progression in ACS.

4. Which associated finding is a common autonomic sign of ACS?

   Diaphoresis. Sympathetic activation in ACS triggers sweating as part of the stress response.

5. Which ECG leads are used to identify an inferior STEMI?

   Leads II, III, and aVF. These leads view the inferior heart wall, detecting ischemia in right coronary artery territory.

6. What ECG finding defines STEMI for prehospital decision-making?

   ST-segment elevation in contiguous leads consistent with infarction. ST elevation indicates transmural ischemia, guiding urgent reperfusion therapy decisions in the field.

7. What is the most common underlying cause of acute coronary syndrome?

   Atherosclerotic plaque rupture with platelet thrombus formation. This mechanism leads to partial or complete coronary artery occlusion, resulting in myocardial ischemia or infarction.

8. What is the primary ECG pattern associated with NSTEMI or unstable angina?

   ST depression and or T-wave inversion (may also be normal early). These changes reflect subendocardial ischemia, distinguishing from STEMI but still requiring urgent evaluation.

9. Which aspirin contraindication should stop you from administering it in suspected ACS?

   True aspirin allergy or active major bleeding. These conditions increase bleeding risk or cause severe reactions, outweighing aspirin's benefits in ACS.

10. Which dysrhythmias are common early complications of acute myocardial infarction?

    Ventricular tachycardia and ventricular fibrillation. Reperfusion injury and irritability in infarcted tissue predispose to these life-threatening arrhythmias.

11. What is the key pathophysiologic difference between angina and myocardial infarction?

    Angina is ischemia; MI includes myocardial necrosis (cell death). Angina involves reversible ischemia without cell death, while MI results from prolonged ischemia causing irreversible myocardial damage.

12. Which symptom description is most consistent with ischemic chest discomfort in ACS?

    Pressure, squeezing, heaviness, or tightness (not sharp pleuritic). Ischemic pain typically manifests as visceral discomfort due to myocardial oxygen deprivation.

13. Which ECG leads are used to identify an anterior STEMI?

    Leads V1 to V4. These precordial leads assess the anterior wall, indicating left anterior descending artery occlusion.

14. What is the immediate prehospital priority when ACS is suspected?

    Early recognition, 12-lead ECG, and rapid transport to PCI-capable care. Timely ECG and transport facilitate rapid reperfusion, improving outcomes in time-sensitive ACS.

15. Which infarct location makes nitroglycerin especially risky due to preload dependence?

    Right ventricular infarction (often with inferior STEMI). RV infarction relies on preload; nitroglycerin reduces it, potentially causing cardiogenic shock.

16. What is the typical prehospital oxygen target range for suspected ACS when oxygen is needed?

    Titrate to $94\%$ to $99\%$ oxygen saturation. This range optimizes oxygen delivery while avoiding hyperoxia-related complications in ACS.

17. Which ECG leads are used to identify a lateral STEMI?

    Leads I, aVL, V5, and V6. These leads evaluate the lateral wall, often involving circumflex artery pathology.

18. Which condition should be considered when chest pain is tearing and radiates to the back, affecting nitroglycerin decisions?

    Aortic dissection (avoid treatments that delay definitive care). Dissection mimics ACS but requires surgical management; nitroglycerin may worsen it by reducing pressure.

19. Which medication history within the last $24$ to $48$ hours contraindicates nitroglycerin?

    PDE-5 inhibitor use (sildenafil, vardenafil, tadalafil). These drugs synergize with nitroglycerin to cause severe hypotension via cGMP pathway.

20. What is the recommended timeframe to obtain a 12-lead ECG in suspected ACS?

    Within 10 minutes of patient contact (as soon as possible). Rapid ECG acquisition enables early STEMI detection and system activation for reperfusion.

21. Which vital sign finding is a common contraindication to nitroglycerin administration?

    Hypotension (systolic BP below local protocol threshold). Low BP exacerbates nitroglycerin-induced vasodilation, risking profound hypotension.

22. What is the preferred destination decision when the 12-lead indicates STEMI and transport time allows?

    Transport directly to a PCI-capable facility with prearrival activation. PCI provides definitive reperfusion for STEMI, with activation minimizing door-to-balloon time.

23. Which patient group commonly presents with atypical ACS symptoms such as dyspnea or weakness?

    Older adults, women, and patients with diabetes. These groups often have altered pain perception or neuropathy, leading to non-classic presentations.

24. Which intervention is recommended for suspected ACS when oxygen saturation is normal?

    Do not give routine oxygen; titrate only if hypoxemic. Routine oxygen can cause vasoconstriction and harm in normoxic patients, per evidence-based guidelines.

25. What is the standard AEMT nitroglycerin dose and maximum number of doses for ACS chest pain?

    $0.4$ mg SL every $5$ min, up to $3$ doses if tolerated. Nitroglycerin relieves ischemia by vasodilation, with limits to prevent cumulative hypotension.

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