Acute Coronary Syndrome and MI: Priority Care

Medical-Surgical · Cardiovascular·Updated 2026-10-27

What it is

Acute coronary syndrome (ACS) covers unstable angina, NSTEMI and STEMI. Each begins when an atherosclerotic plaque ruptures and a thrombus suddenly reduces coronary blood flow. Myocardium beyond the blockage becomes ischemic and then dies, so every early action aims to restore flow (reperfusion) and lower myocardial oxygen demand: time is muscle.

What the NCLEX focuses on

A 12-lead ECG within 10 minutes of arrival; ST elevation in two contiguous leads means STEMI and immediate reperfusion.
Cardiac troponin is the preferred marker of myocardial injury; a single normal result does not rule out MI, so it is repeated per protocol.
Women, older adults and clients with diabetes often present with dyspnea, nausea, fatigue, diaphoresis or epigastric pressure instead of chest pain.
Nitroglycerin is held for systolic BP below 90 mm Hg, heart rate below 50/min, right ventricular infarction, or a phosphodiesterase-5 inhibitor within 24 to 48 hours.
Absolute contraindications to fibrinolytics: any prior intracranial hemorrhage, ischemic stroke within 3 months, active internal bleeding, suspected aortic dissection.
Early complications: dysrhythmias (the most common cause of early death), heart failure (new crackles or S3), cardiogenic shock and papillary muscle rupture (new murmur).

Priority nursing actions

Obtain a 12-lead ECG and start continuous cardiac monitoring.
Give aspirin to chew unless contraindicated, and establish IV access.
Give sublingual nitroglycerin if blood pressure and heart rate allow; give IV morphine for pain unrelieved by nitroglycerin, as prescribed.
Apply oxygen only when SpO2 is below 90% or the client is in respiratory distress.
Draw troponin and prepare for PCI or fibrinolytic therapy.
Monitor rhythm, blood pressure, lung sounds and bleeding after antithrombotic therapy.

Numbers to know

Item	Target	Why it matters
12-lead ECG	Within 10 minutes of arrival	Identifies STEMI
Door-to-balloon (PCI)	90 minutes or less	Limits infarct size
Door-to-needle (fibrinolytic)	30 minutes or less	When PCI is not available in time
Aspirin	162 to 325 mg, chewed, non-enteric-coated	Blocks platelet aggregation
Nitroglycerin SL	0.4 mg every 5 minutes, up to 3 doses	Hold if systolic BP below 90 mm Hg
Oxygen	Give when SpO2 is below 90%	No benefit with normal saturation

Common exam traps

Choosing to wait for the troponin result before reporting ST elevation: wrong because STEMI is diagnosed on the ECG and reperfusion cannot wait.
Choosing routine oxygen for a client with SpO2 95%: wrong because oxygen in normoxemic clients gives no benefit.
Choosing nitroglycerin for a client with BP 86/58 mm Hg or recent sildenafil use: wrong because it causes severe hypotension.
Choosing an antacid for epigastric pressure in an older client with diabetes: wrong because this is an atypical ACS presentation that needs an ECG first.

What to teach

For chest pain, take one nitroglycerin tablet; if pain is unimproved or worse after 5 minutes, call 911.
Never stop aspirin or clopidogrel after a stent without the cardiologist's approval; report black stools or bleeding.
Attend cardiac rehabilitation, stop smoking, and take the prescribed statin.
Sexual activity can resume when the client climbs two flights of stairs without symptoms.

Client handout: After a Heart Attack: Your Recovery (nurse guide and printable patient handout).

Try 2 NCLEX-style questions on this topic

From the NCLEXPace question bank. Pick your answers, then check them inside NCLEXPace.

Question 1 · QID A8B63C73

A client arrives in the emergency department with substernal pressure radiating to the left arm, diaphoresis, and nausea. The discomfort began 25 minutes ago. Which action is the priority?

Select the best answer.

A. Establish IV access and draw cardiac biomarkers.
B. Obtain a 12-lead ECG.
C. Administer chewable aspirin while obtaining vital signs.
D. Obtain a portable chest radiograph before further treatment.

Question 2 · QID 1FFFEC41

A client has ongoing ischemic chest pressure and these findings.

Finding	Value
Heart rate	48/min
Blood pressure	102/64 mm Hg
Oxygen saturation	95% on room air

Classify each potential prescription.

	Expected now	Clarify / withhold
Chew non-enteric-coated aspirin if no contraindication
Routine oxygen solely to raise SpO₂ above 95%
Continuous cardiac monitoring
Sublingual nitroglycerin without reassessing bradycardia and blood pressure
Prepare for urgent reperfusion when indicated

See the answers and full rationales

The correct answers, the reasoning for every option and 3,200+ more NCLEX questions are inside NCLEXPace. Create your account, then choose a plan to open them.

Create Account →

More tips on Medical-Surgical

Acute PancreatitisRecognize acute pancreatitis by pain and lipase, give fluids and pain control first, and catch hypocalcemia, shock and respiratory failure.Bowel Obstruction and NG Tube CareTell small from large bowel obstruction, spot strangulation early, and keep a decompression NG tube placed, patent and safe.Acute Kidney Injury vs Chronic Kidney DiseaseClassify AKI as prerenal, intrarenal or postrenal, follow its phases, and compare it with the staged, irreversible course of CKD.

Sources

Harding MM, Kwong J, Hagler D, Reinisch C. Lewis's Medical-Surgical Nursing: Assessment and Management of Clinical Problems. 12th ed. Elsevier; 2023; Chapter: Coronary Artery Disease and Acute Coronary Syndrome.
Rao SV, et al. 2025 ACC/AHA/ACEP/NAEMSP/SCAI Guideline for the Management of Patients With Acute Coronary Syndromes. Circulation. 2025;151(13):e771-e862.

Practice the NCLEX questions on this topic

3,200+ NCLEX questions with think-like-a-nurse rationales, unfolding case studies and adaptive readiness exams. Start with free practice questions, then choose a plan when you are ready.