Key Points
- Stabilize ABCs; begin targeted evaluation without delaying life-saving therapy.
- Use system-specific risk tools to guide testing and disposition.
- Order high-yield tests first; escalate imaging when indicated.
- Start evidence-based initial therapy and reassess frequently.
Algorithm
- Primary survey and vitals; IV access and monitors.
- Focused history/physical; identify red flags and likely etiologies.
- Order system-appropriate labs and imaging (see Investigations).
- Initiate guideline-based empiric therapy (see Pharmacology).
- Reassess response; arrange consultation and definitive management.
Clinical Synopsis & Reasoning
ACS results from plaque rupture/erosion with downstream thrombosis causing supply‑demand mismatch and myocyte necrosis. Establish diagnosis with serial troponins and ECGs, recognize STEMI equivalents, and differentiate alternative causes of chest pain. Risk‑stratify NSTEMI/UA using validated tools (GRACE/TIMI) to guide invasive timing.
Treatment Strategy & Disposition
Initiate aspirin, anticoagulation, and anti‑ischemic therapy; add P2Y12 inhibitor when an early invasive strategy is planned. Address precipitating factors (tachyarrhythmias, anemia, hypertension) and optimize secondary prevention (statin, ACEi/ARB, β‑blocker). Select radial‑access PCI when feasible to reduce bleeding. Disposition is driven by hemodynamics, ischemic burden, and arrhythmia risk—ICU/telemetry for high‑risk patients.
Epidemiology / Risk Factors
- Atherosclerotic risk (HTN, DM, HLD, smoking)
- Age/family history of premature CAD
Investigations
| Test | Role / Rationale | Typical Findings | Notes |
|---|---|---|---|
| EKG | Rhythm/ischemia | ST-T changes/arrhythmia | Serial |
| Troponin | Myocardial injury | Dynamic rise/fall | Trend |
| CXR | Pulmonary edema/size | Cardiomegaly/edema | |
| BMP/Mg2+ | Electrolytes/renal | Derangements | |
| CBC/Coags | Bleeding risk | Abnormal/INR |
Antithrombotic Snapshot
| Class | Agents | Notes |
|---|---|---|
| Antiplatelet | Aspirin + ticagrelor/clopidogrel | Loading dose in ED |
| Anticoagulant | UFH or enoxaparin | Bivalirudin in select PCI scenarios |
Pharmacology
| Medication | Mechanism | Onset | Role in Therapy | Limitations |
|---|---|---|---|---|
| P2Y12 inhibitor (ticagrelor/clopidogrel) | ADP receptor blockade | Hours | Dual antiplatelet with PCI/NSTEMI | Bleeding; dyspnea (ticagrelor) |
| Aspirin | COX-1 inhibition (platelet) | Minutes | Immediate antiplatelet | GI bleed; allergy |
| Heparin (UFH) | Antithrombin activation | Immediate | Anticoag during ACS/PCI | Bleeding, HIT |
| Nitroglycerin | Venodilation | Minutes | Anti-ischemic symptom relief | Hypotension; avoid with PDE5i or RV infarct |
| High-intensity statin | HMG-CoA reductase inhibition | Days | Secondary prevention | Hepatotoxicity, myopathy |
Prognosis / Complications
- Prognosis by ischemic burden/LV function
- Arrhythmias and HF are complications
Patient Education / Counseling
- Explain red flags and when to seek emergent care.
- Reinforce medication adherence and follow-up plan.
Notes
Avoid P2Y12 loading if immediate CABG is likely. Manage precipitating factors such as anemia, sepsis, or tachyarrhythmia.