NSTEMI and non-ST-elevation ACS: workup and management
NSTE-ACS covers NSTEMI (rising/falling troponin above the 99th percentile with ischemia) and unstable angina. Separate type 1 MI from type 2 MI and myocardial injury, risk-stratify with GRACE, start antithrombotic therapy and plan angiography by risk, following the 2025 ACC/AHA ACS guideline.
Working diagnosis
Adult · US guidelines
Draft · awaiting physician review
01Orient
What's new in the evidence
- 2025 ACC/AHA/ACEP/NAEMSP/SCAI ACS guideline: ticagrelor or prasugrel preferred over clopidogrel; invasive strategy for intermediate/high risk, radial access
- Aspirin can be stopped after 1–4 weeks in patients who need oral anticoagulation; de-escalation to clopidogrel after 1 month is reasonable
- Add a nonstatin (ezetimibe, PCSK9 inhibitor) if LDL-C ≥70 mg/dL despite maximal statin
- SENIOR-RITA (2024): in patients ≥75, routine invasive strategy did not reduce CV death or MI; frailty assessment guides the decision
- REDUCE-AMI (2024): routine beta-blocker after MI with EF ≥50% did not reduce death or MI
Differential diagnoses
- Type 1 MI (plaque rupture) (can't miss)
- Type 2 MI from supply–demand mismatch (anemia, sepsis, tachyarrhythmia, hypotension)
- Nonischemic myocardial injury: myocarditis, takotsubo, PE, sepsis, CKD, heart failure
- Aortic dissection (can't miss: no antithrombotics)
- STEMI equivalents: posterior MI, de Winter T waves, Sgarbossa-positive LBBB (can't miss)
- Coronary vasospasm, SCAD (young women, peripartum), MINOCA
02Assess
Risk scores and decision tools
- GRACE score to time angiography (>140 = high risk, early invasive within 24 hours)
- TIMI risk score
- High-sensitivity troponin delta (0/1 h or 0/2 h)
- CRUSADE or ARC-HBR for bleeding risk
- Clinical Frailty Scale in older adults
Key history questions
- Character, duration and timing of chest pain; ongoing pain now
- Associated dyspnea, diaphoresis, syncope, palpitations
- Prior CAD, PCI, CABG; cardiac risk factors
- Cocaine or stimulant use
- Bleeding history, recent surgery, anticoagulant use
- Triggers for type 2 MI: bleeding, infection, arrhythmia
Examination findings
- Hemodynamics, signs of cardiogenic shock
- Heart failure (Killip class), new murmur (MR, VSD)
- Pulse and BP differential (dissection)
- Access site assessment for radial approach
03Investigate
Initial investigations
- 12-lead ECG within 10 minutes; repeat with symptoms; posterior leads if ST depression V1–V3
- High-sensitivity troponin at 0 and 1–3 hours
- CBC, BMP, magnesium, coagulation, lipid panel, HbA1c
- Chest X-ray; point-of-care echo for wall motion and complications
Advanced investigations
- Coronary angiography: immediate (<2 h) if refractory angina, instability or arrhythmia; early (<24 h) if GRACE >140; inpatient otherwise
- Formal echocardiogram for LV function
- Cardiac MRI for MINOCA or suspected myocarditis
04Treat
Immediate management
- Aspirin 162–325 mg chewed, then 81 mg daily
- Parenteral anticoagulation: unfractionated heparin (if early cath likely) or enoxaparin 1 mg/kg SC twice daily
- Nitroglycerin for ongoing ischemic pain unless hypotensive or recent PDE5 inhibitor
- Oxygen only if SpO₂ <90%
First-line treatment
- P2Y12 inhibitor: ticagrelor 180 mg then 90 mg twice daily (or prasugrel 60 mg then 10 mg daily at PCI; avoid if prior stroke/TIA)
- High-intensity statin (atorvastatin 80 mg)
- Beta-blocker within 24 hours if no HF, shock or bradycardia; especially with reduced EF
- ACE inhibitor or ARB for EF ≤40%, diabetes, hypertension or CKD
Second-line treatment
- Clopidogrel 300–600 mg load if high bleeding risk or on oral anticoagulation
- On oral anticoagulation: drop aspirin after 1–4 weeks and continue clopidogrel with the anticoagulant
- Type 2 MI: treat the underlying cause; antithrombotics are not routine
Specialist referrals
- Cardiology for all type 1 NSTE-ACS
- Cardiac rehabilitation at discharge
- Cardiothoracic surgery for multivessel or left main disease
05Disposition
Admission criteria
- All type 1 NSTEMI and high-risk unstable angina; telemetry
- Ongoing pain, heart failure, arrhythmia or instability: CCU
Safe discharge criteria
- Revascularized or medically optimized and pain free
- DAPT, statin and secondary prevention started; affordability checked
- Cardiology follow-up and cardiac rehabilitation referral
Follow-up timing
- Cardiology within 2 weeks
- Lipid panel 4–12 weeks after starting or changing statin
Patient instructions
- Do not stop antiplatelet therapy without speaking to cardiology
- Call 911 for chest pain lasting >5 minutes
- Smoking cessation
Monitoring
- Telemetry 24–48 hours
- Daily ECG and troponin until peak
- Access-site and bleeding checks
Clinical pearls and pitfalls
- Type 2 MI and nonischemic injury are more common than type 1 MI on medical wards; the troponin pattern and context decide
- Avoid prasugrel in prior stroke/TIA; use 5 mg if <60 kg and generally avoid if ≥75
- Avoid NSAIDs after MI
RefGuidelines and landmark evidence
- GuidelineACC/AHA/ACEP/NAEMSP/SCAI – Guideline for the Management of Acute Coronary Syndromes (2025)PubMed
- GuidelineFourth Universal Definition of Myocardial Infarction (2018)PubMed
- TrialPLATO: ticagrelor vs clopidogrel in ACS (2009)PubMed
- TrialSENIOR-RITA: invasive vs conservative strategy in older adults with NSTEMI (2024)PubMed
- TrialREDUCE-AMI: beta-blockers after MI with preserved EF (2024)PubMed
For education only. Typical adult starting points; confirm doses against renal function, allergies, interactions and your institution's protocols. Not a substitute for clinical judgment or senior review.