| Component | 0 | 1 | 2 |
|---|---|---|---|
| History | Slightly suspicious | Moderately | Highly suspicious |
| ECG | Normal | Non-specific | ST deviation |
| Age | <45 | 45–64 | ≥65 |
| Risk Factors | None | 1–2 | ≥3 or known CAD |
| Troponin | Normal | 1–3×ULN | >3×ULN |
| Feature | STEMI | NSTEMI | Unstable Angina |
|---|---|---|---|
| Pathology | Complete coronary occlusion (transmural) | Partial occlusion / subtotal thrombus | Partial occlusion, no necrosis |
| ECG | ST elevation ≥1mm in 2 contiguous leads (or new LBBB) | ST depression, T-wave inversion, or nonspecific | Normal or nonspecific changes |
| Troponin | Elevated (rises within 3–6h) | Elevated | Normal |
| Cath timing | Emergent PCI (<90 min door-to-balloon) [STEMI Protocol] | Early invasive (2–24h) or ischemia-guided [NSTEMI Protocol] | Risk-stratified approach |
| Mortality (30d) | ~6–8% | ~3–5% | <1% |
| Feature | Type 1 MI (Plaque Rupture) | Type 2 MI (Supply-Demand Mismatch) |
|---|---|---|
| Mechanism | Atherosclerotic plaque rupture/erosion → thrombotic occlusion | Oxygen supply-demand mismatch WITHOUT plaque rupture |
| Triggers | Spontaneous plaque event | Tachycardia, anemia, sepsis, hypotension, respiratory failure, hypertensive crisis |
| Treatment | Antiplatelet + anticoag + PCI/CABG | Treat the underlying cause (e.g., transfuse, treat sepsis, rate control) |
| Cath indicated? | Yes | Usually no (unless type 1 cannot be excluded) |
| DAPT needed? | Yes (12 months) | Not routinely, depends on underlying CAD |
| Killip Class | Findings | 30-Day Mortality |
|---|---|---|
| I | No HF signs | ~6% |
| II | Rales, S3, JVD | ~17% |
| III | Frank pulmonary edema | ~38% |
| IV | Cardiogenic shock (SBP <90, end-organ hypoperfusion) | ~67% |
| Intervention | Details |
|---|---|
| Aspirin | 325mg chewed immediately |
| O2 | Only if SpO2 <90% DETO2X-AMI AVOID |
| Nitroglycerin | 0.4mg SL q5min ×3. AVOID: RV infarct, SBP <90, PDE5i use |
| Heparin | UFH 60u/kg bolus → 12u/kg/hr (or enoxaparin 1mg/kg q12h) |
| Beta-blocker | Within 24h if stable. Avoid in HF, bradycardia, cocaine |
| Atorvastatin | 80mg immediately (high-intensity) |
| Scenario | Target | Details |
|---|---|---|
| STEMI, PCI-capable center [Full Protocol] | <90 min door-to-balloon | Activate cath lab from ED or EMS. Goal <60 min for walk-in STEMIs |
| STEMI, transfer to PCI center | <120 min first medical contact to device | If transfer time exceeds this, give fibrinolytics at presenting hospital |
| Fibrinolysis (if PCI unavailable) | <30 min door-to-needle | Tenecteplase (TNK) weight-based single bolus. Rescue PCI if no ST resolution by 60–90 min |
| NSTEMI, early invasive [Full Protocol] | 2–24 hours | High-risk features: refractory angina, hemodynamic instability, new HF, GRACE >140 TIMACS, 2009 |
| NSTEMI, ischemia-guided | Selective cath | Low-risk, no recurrent symptoms, negative stress test |
| Agent | Loading Dose | Maintenance | Timing / Notes |
|---|---|---|---|
| Aspirin | 325 mg chewed | 81 mg daily (lifelong) | Give immediately to ALL ACS patients |
| Ticagrelor | 180 mg PO | 90 mg BID × 12 mo | Preferred P2Y12. Reversible. Use only with ASA 81mg. PLATO, 2009 |
| Prasugrel | 60 mg PO | 10 mg daily × 12 mo | STEMI going to PCI. Avoid if prior stroke/TIA, age ≥75, wt <60 kg. TRITON-TIMI 38, 2007 |
| Clopidogrel | 600 mg (PCI) or 300 mg | 75 mg daily × 12 mo | Alternative. CYP2C19 poor metabolizers = reduced efficacy |
| GP IIb/IIIa (antiplatelet -bailout only, bailout = rescue mid-procedure) | Eptifibatide or tirofiban | Infusion during/post PCI | High thrombus burden only. NOT routine before cath. EARLY-ACS, 2009. Why bailout only? Strongest antiplatelet (blocks final common pathway) but biggest bleeding risk -modern P2Y12 + bivalirudin + DES deliver similar ischemic benefit with less bleeding. |
| Cangrelor | 30 mcg/kg IV bolus | 4 mcg/kg/min | IV P2Y12 for NPO patients in cath lab. Immediate onset/offset |
| Score | Components | Interpretation |
|---|---|---|
| TIMI (NSTEMI/UA) | Age ≥65, ≥3 CAD RFs, known CAD, ASA use past 7d, ≥2 angina episodes/24h, ST deviation, elevated troponin (1 pt each, max 7) | 0–2: Low (5%). 3–4: Intermediate. 5–7: High (41%) → early invasive |
| GRACE | Age, HR, SBP, Cr, Killip class, cardiac arrest, ST deviation, troponin (calculator-based) | <108: Low (<1% death). 109–140: Intermediate. >140: High (>3%) → early invasive <24h |
| Letter | Class | Drug / Target | Rationale |
|---|---|---|---|
| A | ACE inhibitor (or ARB) | Lisinopril 2.5–20 mg daily | Prevents remodeling. Start within 24h if stable. EF ≤40%, anterior MI, HF, DM. SAVE, 1992 |
| B | Beta-blocker | Metoprolol succinate or carvedilol | Reduces mortality, prevents arrhythmias. Avoid in cardiogenic shock |
| C | Cholesterol / Statin | Atorvastatin 80 mg or rosuvastatin 40 mg | High-intensity for ALL post-ACS. Target LDL <70. PROVE IT, 2004 |
| D | Dual antiplatelet | ASA 81 mg + ticagrelor 90 BID | 12 months standard. Reduces stent thrombosis and recurrent events |
| E | Eplerenone (MRA) | Eplerenone 25–50 mg daily | If EF ≤40% + HF symptoms or DM. Monitor K+ and Cr. EPHESUS, 2003 |
| Topic | Old practice | 2025 update | Why / trial basis |
|---|---|---|---|
| DAPT after PCI CHANGED | 12 mo DAPT (ASA + P2Y12) for everyone | 1 mo DAPT, then ticagrelor monotherapy (Class 1, LOE A). 12 mo still default if not at high bleeding risk. | Aspirin withdrawal at 1 mo with continued ticagrelor cuts BARC 2/3/5 bleeding ~44% with no increase in ischemic events. Benefit largest in NSTE-ACS. TWILIGHT, 2019 TICO, 2020 T-PASS, 2023 |
| P2Y12 choice | Clopidogrel acceptable | Ticagrelor or prasugrel preferred over clopidogrel post-PCI | More potent platelet inhibition reduces CV death/MI/stroke. Reserve clopidogrel for high bleeding risk or when ticagrelor/prasugrel are contraindicated. PLATO, 2009 |
| AFib + PCI triple therapy CHANGED | Triple therapy (OAC + ASA + P2Y12) for variable durations | Short triple (1 to 4 weeks), then drop ASA, then OAC + clopidogrel through month 12, then OAC alone (Class 1) | Adding ASA to OAC + P2Y12 increases bleeding 3 to 4 fold without reducing ischemic events. Clopidogrel preferred over ticagrelor/prasugrel as the dual partner (bleeding). DOACs (especially apixaban) preferred over warfarin. AUGUSTUS, 2019 PIONEER AF-PCI, 2016 |
| LDL target post-ACS CHANGED | Add non-statin if LDL ≥ 70 on max statin | Non-statin if LDL ≥ 70 (Class 1). Reasonable to intensify if LDL 55 to <70 on max statin (Class 2a, lower threshold) | Post-ACS is the highest-risk window. Adding ezetimibe or PCSK9 inhibitor reduces CV events. The 2025 guideline pushes the intensification floor lower than the 2018 cholesterol guideline. FOURIER, 2017 ODYSSEY OUTCOMES, 2018 |
| Intravascular imaging UPGRADED | IVUS/OCT Class 2a (2021 revasc guideline) | Class 1 for PCI guidance, especially complex lesions (left main, long lesions, bifurcation, CTO) | Lower cardiac death and stent thrombosis vs angiography alone. RENOVATE-COMPLEX-PCI, 2023 ILUMIEN IV, 2023 |
| Multivessel disease CHANGED | Culprit-only PCI was the conservative default | Complete revascularization (Class 1). Treat severely stenotic non-culprit lesions same setting or staged. | Reduces recurrent MI and CV death vs culprit-only. COMPLETE, 2019 MULTISTARS-AMI, 2023 FULL REVASC, 2024 |
| Cardiogenic shock NEW | No proven mechanical support; routine pump use unsupported | Microaxial flow pump (Impella CP) reasonable in select AMI shock (Class 2a). Transfer to shock center (Class 1). | First positive shock RCT to show mortality benefit. Patient selection critical (anterior STEMI, no severe RV failure). Caveats: more bleeding, limb ischemia, AKI. DanGer Shock, 2024 |
| Vascular access | Femoral default | Radial preferred over femoral for PCI in ACS (Class 1) | Reduces bleeding, vascular complications, and mortality. MATRIX, 2015 RIVAL, 2011 |
| hs-Troponin protocols | Serial 3 to 6 hr troponins standard | 0/1h or 0/2h hs-cTn algorithms formalized for rule-in/rule-out | Faster ED disposition without missed MIs. ESC 2020 already endorsed; 2025 ACC/AHA brings US guidance in line. |
| Periprocedural anticoag UNCHANGED | UFH for NSTE-ACS; UFH or bivalirudin for STEMI PCI | Same: UFH Class 1 for NSTE-ACS; bivalirudin Class 2a alternative for STEMI PCI, Class 2b for NSTE-ACS | UFH remains the workhorse. Bivalirudin reduces bleeding but did not unseat UFH in trials (BRIGHT-4 was the closest positive signal). Fondaparinux alone does NOT cover PCI (catheter thrombosis risk), add UFH bolus at cath. |
ACC/AHA guidelines grade every recommendation on two axes: Class of Recommendation (strength) and Level of Evidence (quality of data). The two are written together, e.g., "Class 1, LOE A."
| Class | Strength | Phrase you'll see | Bedside translation |
|---|---|---|---|
| Class 1 | Strong (Benefit >>> Risk) | "is recommended", "should", "is indicated" | Standard of care. Skipping it without a documented reason is below the standard. |
| Class 2a | Moderate (Benefit >> Risk) | "is reasonable", "can be useful" | Lean toward doing it. Most experts would. |
| Class 2b | Weak (Benefit ≥ Risk) | "may be reasonable", "may be considered" | Optional, case-by-case. |
| Class 3: No Benefit | Moderate against | "is not recommended" | Don't do it, no upside. |
| Class 3: Harm | Strong against | "potentially harmful", "should not" | Don't do it, actively harmful. |
| Level of Evidence | Source |
|---|---|
| LOE A | Multiple high-quality RCTs or meta-analyses. Best evidence. |
| LOE B-R | One or more moderate-quality Randomized trials. |
| LOE B-NR | Well-designed Non-Randomized studies. |
| LOE C-LD | Limited Data: small studies, registries, retrospective. |
| LOE C-EO | Expert Opinion only, no real evidence. |
| Drug | Dose | Notes |
|---|---|---|
| Aspirin | 325mg chew, then 81mg daily | ALL ACS unless true allergy |
| Ticagrelor | 180mg load, 90mg BID | Preferred P2Y12 (PLATO trial). Use aspirin 81mg only |
| Clopidogrel | 600mg load, 75mg daily | Alternative. CYP2C19 polymorphisms |
| Heparin | 60u/kg, 12u/kg/hr | aPTT 1.5–2.5× control |
Patient: 58M smoker, acute crushing chest pain radiating to left arm × 45 min, diaphoresis, nausea. HR 95, BP 142/88, SpO2 96%.
ECG: ST elevation 3mm in V1–V4 with reciprocal ST depression in II, III, aVF. Anterior STEMI, LAD territory.
Immediate actions (first 10 minutes):
Cath findings: 100% proximal LAD occlusion. DES placed. TIMI 3 flow restored. Door-to-balloon time: 68 minutes.
Post-PCI orders:
Key lesson: Anterior STEMI = large territory at risk. Time is myocardium. ABCDE medications are essential at discharge, especially with reduced EF.
Patient: 72F with DM, HTN, HLD. Substernal pressure at rest × 2h, now improving. HR 82, BP 158/92, SpO2 97%.
ECG: ST depression 1.5 mm in V4–V6, T-wave inversions in I, aVL. No ST elevation.
Labs: hs-troponin 0h = 85 ng/L (elevated), 3h = 142 ng/L (rising). Cr 1.1, K 4.2.
Risk stratification:
Management:
Key lesson: NSTEMI is not benign. Use GRACE/TIMI to identify high-risk patients who benefit from early invasive strategy (<24h). This patient had multiple high-risk features mandating prompt catheterization.
Patient: 68M admitted for pneumonia/sepsis. HR 128, BP 88/54, SpO2 89% on 4L NC. Febrile to 39.2°C. Known 2-vessel CAD (prior cath showed 60% LAD, 50% RCA).
ECG: Sinus tachycardia, no acute ST changes. Nonspecific T-wave flattening laterally.
Labs: hs-troponin 0h = 65 ng/L, 3h = 78 ng/L (mildly elevated, stable). Lactate 3.8. WBC 18k.
Clinical reasoning:
Management:
Key lesson: Not every troponin elevation is a Type 1 MI. The critical question: is there a plaque event, or is there a supply-demand problem? Type 2 MI is treated by fixing the underlying trigger. Reflexive catheterization causes harm.
| Parameter | Frequency |
|---|---|
| Telemetry | Continuous. VT/VF risk highest 24–48h |
| Troponins | 0h, 3h (hs-trop) |
| ECGs | q15–30min if symptoms persist |