Pass the Shift

Med-Surg · Cardiovascular

Acute Coronary Syndrome & Myocardial Infarction

Last reviewed October 15, 2026 by Kristina, RN

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On this page
  1. 1. Overview and Pathophysiology
  2. 2. Causes and Risk Factors
  3. 3. Signs and Symptoms
  4. 4. Diagnostics and Labs
  5. 5. Priority Nursing Assessments
  6. 6. Priority Nursing Interventions
  7. 7. Medications
  8. 8. Patient Education
  9. 9. Complications
  10. 10. Memory Aids
  11. 11. NCLEX-Style Practice Questions
  12. References

Prepared for Pass the Shift (owner: Kristina, RN). Always follow your facility’s protocols, provider orders, and current drug references.

1. Overview and Pathophysiology

is a spectrum of sudden coronary blood-flow problems, almost always from a plaque that ruptures and forms a thrombus. How much the clot blocks the artery decides the presentation:

TypeECG & markersCore idea
Unstable anginaIschemic symptoms; no troponin rise; ECG may show ST depression/T-wave changesPartial occlusion; myocardium is threatened but not yet necrotic
Troponin elevates; usually ST depression or T-wave inversion (no persistent ST elevation)Partial occlusion with myocardial injury
Persistent ST elevation (or new LBBB) plus rising troponinComplete occlusion → transmural injury; needs immediate reperfusion

Time is muscle. Ischemia becomes irreversible necrosis within hours. Nursing priorities focus on rapid recognition, 12-lead ECG within 10 minutes of arrival, and getting the patient to (or fibrinolysis when PCI isn’t available in time).

Angina vs ACS. Stable angina is predictable with exertion and relieved by rest or nitroglycerin. ACS pain is new, more intense, occurs at rest, or is “crescendo.”

2. Causes and Risk Factors

  • Atherosclerotic plaque rupture with thrombosis (most common)
  • Coronary spasm, embolism, spontaneous coronary artery dissection (less common)
  • Modifiable risks: smoking, hypertension, diabetes, dyslipidemia, obesity, inactivity, high stress
  • Nonmodifiable: age, male sex (earlier onset), family history, prior CAD/MI
  • Atypical presentations are more common in women, older adults, and people with diabetes: fatigue, nausea, epigastric pain, dyspnea, jaw/back pain without classic crushing chest pain

3. Signs and Symptoms

  • Chest pressure, tightness, or crushing pain (often substernal) lasting > 20 minutes, may radiate to jaw, neck, left arm, or back
  • Diaphoresis, nausea/vomiting, anxiety (“impending doom”)
  • Dyspnea, syncope or near-syncope, palpitations
  • Signs of poor perfusion: cool clammy skin, hypotension, tachycardia or bradycardia, new murmur (papillary muscle rupture after MI)
  • Complications may appear early: dysrhythmias, heart failure, cardiogenic shock

4. Diagnostics and Labs

Lab reference ranges vary by laboratory. Always use your facility’s ranges.

TestTypical reference / targetNursing relevance
Troponin I/TAssay-dependent; often < 0.04 ng/mL for “negative”Most specific marker of myocardial injury; serial draws (e.g., 0, 3–6 h)
CK-MBLab-dependentLess specific; sometimes used for reinfarction timing
12-lead ECG—STAT within 10 min; look for ST elevation, depression, T-wave changes, new LBBB
BNP / NT-proBNPSee HF guideRising values suggest concurrent HF
Lipid panel, HbA1c, CBC, BMPPer labRisk profile and baseline for meds/contrast
Coagulation (PT/INR, aPTT, platelets)See facilityImportant before anticoagulation / PCI
Chest X-ray—Alternative diagnoses (pneumothorax, aortic issues need other imaging)
Coronary angiography—Definitive vessel visualization during PCI

5. Priority Nursing Assessments

  1. ABCs and pain: OLDCARTS/PQRST; note onset time and time last known well for reperfusion decisions
  2. Vital signs and perfusion every few minutes during acute phase; continuous SpO₂ and telemetry
  3. 12-lead ECG immediately and with any new pain or rhythm change
  4. Heart and lung sounds: new S3, murmur, crackles → possible HF or mechanical complication
  5. Bleeding risk once anticoagulants, antiplatelets, or fibrinolysis are given
  6. Post-PCI access site: distal pulses, color/temp, hematoma, bleeding; keep extremity straight per protocol
  7. Psychosocial: fear, denial, teaching readiness

6. Priority Nursing Interventions

Suspected ACS (team-based; follow protocol):

  1. Keep the patient on bed rest; calm environment
  2. Oxygen only if hypoxemic (many protocols: SpO₂ < 90% or respiratory distress)—avoid routine high-flow O₂
  3. 12-lead ECG within 10 minutes; continuous monitoring
  4. Establish IV access; draw labs including troponin
  5. Aspirin 162–325 mg chewed (if not contraindicated) as ordered
  6. Nitroglycerin per protocol if BP allows; never with recent PDE-5 inhibitors (sildenafil, tadalafil)
  7. Anticoagulation / P2Y12 inhibitor / beta blocker / statin as ordered
  8. STEMI: activate cath lab; goal door-to-balloon often ≤ 90 minutes. If PCI unavailable timely, fibrinolysis may be considered within its window
  9. Treat pain, nausea, anxiety; prepare for defibrillation if VT/VF occurs

Post-cardiac catheterization: check site and distal pulses frequently; watch for retroperitoneal bleed (back/flank pain, hypotension); encourage fluids if contrast used and kidneys allow.

7. Medications

Class / examplesHow it helpsKey nursing considerations
Antiplatelet: aspirinBlocks platelet aggregationChewable on arrival if ordered; lifelong secondary prevention unless contraindicated
P2Y12 inhibitors (clopidogrel, ticagrelor, prasugrel)Dual antiplatelet therapy (DAPT) after ACS/stentBleeding risk; prasugrel avoided in prior stroke/TIA; ticagrelor—dyspnea, no high-dose aspirin
Anticoagulants (UFH, enoxaparin, bivalirudin)Limit clot growth during ACS/PCIMonitor aPTT or anti-Xa; watch bleeding; protamine reverses heparin
Nitrates (nitroglycerin SL/IV/paste)Lower preload (and some afterload); relieve ischemic painCheck BP before each dose; hold if hypotensive or with PDE-5 inhibitors; headache common
Beta blockers (metoprolol)Reduce O₂ demand; limit infarct size; prevent arrhythmiasHold for bradycardia, decompensated HF, severe asthma/COPD per order
ACE inhibitors / ARBsRemodeling prevention post-MI, especially with reduced EFWatch K⁺, creatinine, cough/angioedema
High-intensity statins (atorvastatin, rosuvastatin)Plaque stabilization; mortality benefitNight dosing often preferred; watch LFTs/muscle pain
MorphinePain/anxiety when nitrates insufficientCan mask symptoms and delay absorption of oral antiplatelets; use judiciously per protocol
Fibrinolytics (alteplase, tenecteplase)Dissolve clot when timely PCI unavailableStrict inclusion/exclusion (recent stroke, active bleed, etc.); watch for reperfusion arrhythmias and bleeding

8. Patient Education

  • Call 911 for chest pain lasting > a few minutes, especially with sweating, nausea, or dyspnea—do not drive yourself
  • Take nitroglycerin as prescribed (often sit/lie down; call EMS if pain persists after recommended doses)
  • Heart-healthy lifestyle: quit smoking, take meds daily, cardiac rehab, Mediterranean-style diet, gradual activity per provider
  • Dual antiplatelet therapy after a stent: do not stop early—stent thrombosis risk
  • Know bleeding precautions while on antiplatelets/anticoagulants
  • Control BP, diabetes, and lipids; keep follow-up appointments

9. Complications

  • Dysrhythmias (PVCs, VT, VF, heart blocks)—highest risk early after MI
  • Heart failure / cardiogenic shock
  • Papillary muscle rupture → acute mitral regurgitation (new holosystolic murmur, flash pulmonary edema)
  • Ventricular septal rupture or free-wall rupture (tamponade)
  • Pericarditis (including Dressler syndrome days–weeks later)
  • Bleeding from reperfusion therapy or access site
  • Reinfarction or stent thrombosis

10. Memory Aids

  • “Time is muscle” and “ECG in 10”
  • STEMI = ST Elevation → cath lab STAT; NSTEMI = enzyme-positive without ST elevation
  • Aspirin chewed, nitro if BP allows, O₂ only if hypoxic
  • “No nitro with the -afils” (PDE-5 inhibitors)
  • Post-femoral PCI: “Site, pulse, straight leg, flat-ish”

11. NCLEX-Style Practice Questions

1. A client arrives with crushing substernal pain for 40 minutes. Which action is the nurse’s priority?

A. Draw a lipid panel
B. Obtain a 12-lead ECG
C. Give oral metoprolol
D. Encourage ambulation to the bathroom

Answer: B. ACS protocols prioritize a 12-lead ECG within 10 minutes to identify STEMI and start reperfusion. Labs and meds follow; ambulation increases cardiac demand.

2. Two hours after femoral PCI, the client says the groin “feels warm and wet.” What should the nurse do first?

A. Raise the head of the bed to 60°
B. Check the insertion site and apply pressure if bleeding
C. Document and reassess in 1 hour
D. Encourage the client to flex the hip

Answer: B. Warm/wet sensation suggests bleeding. Assess immediately and apply firm pressure per protocol. Raising the HOB or flexing the hip increases bleeding risk.

3. Which statement about oxygen in suspected ACS is correct?

A. Apply a non-rebreather to every client with chest pain
B. Give oxygen only when SpO₂ is low or the client is in respiratory distress, per protocol
C. Oxygen always shrinks infarct size
D. Hold oxygen until after PCI

Answer: B. Routine high-flow oxygen is not recommended in normoxic clients; titrate to protocol targets when hypoxemia or distress is present.

4. A client took sildenafil yesterday evening and now has chest pain. Nitroglycerin is ordered. What should the nurse do?

A. Give the nitroglycerin as ordered
B. Hold nitroglycerin and notify the provider because of severe hypotension risk
C. Give half the nitroglycerin dose
D. Give nitroglycerin with IV fluids prophylactically

Answer: B. Combining nitrates with PDE-5 inhibitors can cause life-threatening hypotension.

5. Which client is most likely to have an atypical MI presentation?

A. 45-year-old man with crushing pain radiating to the left arm
B. 78-year-old woman with diabetes who reports sudden fatigue and nausea
C. 50-year-old man clutching his chest after shoveling snow
D. 55-year-old man with known angina relieved by rest

Answer: B. Older adults, women, and clients with diabetes often present with fatigue, nausea, dyspnea, or epigastric discomfort rather than classic pain.

References

Lawton, J. S., Tamis-Holland, J. E., Bangalore, S., Bates, E. R., Beckie, T. M., Bischoff, J. M., Bittl, J. A., Cohen, M. G., DiMaio, J. M., Don, C. W., Fremes, S. E., Gaudino, M. F., Goldberger, Z. D., Grant, M. C., Jaswal, J. B., Kurlansky, P. A., Mehran, R., Metheus, T. A., Nnacheta, L. C., … Zwischenberger, B. A. (2022). 2021 ACC/AHA/SCAI guideline for coronary artery revascularization. Circulation, 145(11), e18–e114. https://doi.org/10.1161/CIR.0000000000001038

MedlinePlus. (n.d.). Heart attack. National Library of Medicine. Retrieved October 15, 2026, from https://medlineplus.gov/heartattack.html

National Council of State Boards of Nursing. (2026). 2026 NCLEX-RN test plan. https://www.nclex.com/test-plans.page

Ojha, N., & Dhamoon, A. S. (2023). Myocardial infarction. In StatPearls. StatPearls Publishing. https://www.ncbi.nlm.nih.gov/books/NBK537076/

O’Gara, P. T., Kushner, F. G., Ascheim, D. D., Casey, D. E., Jr., Chung, M. K., de Lemos, J. A., Ettinger, S. M., Fang, J. C., Fesmire, F. M., Franklin, B. A., Granger, C. B., Krumholz, H. M., Linderbaum, J. A., Morrow, D. A., Newby, L. K., Ornato, J. P., Ou, N., Radford, M. J., Tamis-Holland, J. E., … Zhao, D. X. (2013). 2013 ACCF/AHA guideline for the management of ST-elevation myocardial infarction. Circulation, 127(4), e362–e425. https://doi.org/10.1161/CIR.0b013e3182742cf6