Acute Coronary Syndrome Pathways

Interactive clinical decision tool for hospitalists. STEMI & NSTEMI pathways with timing cutoffs, antiplatelet/anticoagulation protocols, and perioperative management.

STEMI NSTEMI Unstable Angina

Critical Time Windows

Delays beyond these thresholds directly increase mortality. Memorize these numbers.

≤90

minutes

Door-to-Balloon (STEMI)
First medical contact to PCI wire crossing. ≤120 min if transfer. Every 30-min delay → 7.5% relative increase in mortality.

≤30

minutes

Door-to-Needle (if no PCI)
Fibrinolytic administration when PCI not available within 120 min. TNKase weight-based single bolus preferred.

≤24

hours

Early Invasive (NSTEMI)
Catheterization within 24h for high-risk NSTEMI (GRACE >140, ongoing ischemia, hemodynamic instability, new HF).

Interactive Pathway Simulator

Walk through a clinical scenario step by step. Choose wisely — wrong decisions show real-world consequences.

STEMI — Step 1

Antiplatelet & Anticoagulation Reference

Dosing, timing, and perioperative management — the numbers you need at the bedside.

DAPT Loading Doses

Agent	Load	Maintenance	Notes
Aspirin	325 mg PO	81 mg daily	Non-enteric coated for loading; chewed
Ticagrelor	180 mg PO	90 mg BID	Preferred per ACC/AHA. ASA must be ≤100mg. Reversible P2Y12 inhibitor.
Clopidogrel	600 mg PO	75 mg daily	300 mg if ≥75 yr + fibrinolysis. CYP2C19 poor metabolizers → reduced efficacy.
Prasugrel	60 mg PO	10 mg daily (5 mg if <60 kg)	CI if prior CVA/TIA. Avoid if ≥75 yr. Only post-angiography (coronary anatomy known).

DAPT Duration by Scenario

Scenario	Minimum DAPT	Preferred	Notes
DES post-ACS	6 months	12 months	Standard of care; extend to 18–36 mo if high ischemic + low bleed risk (PEGASUS)
BMS post-ACS	1 month	12 months	BMS rarely used now; same ACS-driven DAPT duration applies
High bleed risk	1–3 months	3–6 months	MASTER DAPT / STOPDAPT-3: abbreviated DAPT safe with current-gen DES
Medical (no PCI)	1 month	12 months	Ticagrelor + ASA for 12 mo regardless of PCI (PLATO)
Post-CABG	12 months	12 months	Resume P2Y12 when surgical team clears (typically POD 2–5). ASA never interrupted.
ACS + OAC (AF)	1–4 weeks triple	12 mo dual	Triple Rx (OAC+ASA+P2Y12) → drop ASA at 1–4 wk → OAC + clopidogrel × 12 mo (AUGUSTUS)

Pre-CABG P2Y12 Washout

Agent	Hold Before CABG	Mechanism	Key Point
Ticagrelor	3–5 days	Reversible, direct-acting	Shorter washout than clopidogrel; reversibility allows faster recovery of platelet function
Clopidogrel	5 days	Irreversible, prodrug	Requires new platelet generation (7–10 day lifespan); 5 days per AHA/ACC guidelines
Prasugrel	7 days	Irreversible, prodrug	Most potent irreversible inhibition → longest washout. Highest surgical bleeding risk.
Cangrelor	1 hour	Reversible, IV	Ultra-short half-life (3–6 min). Bridge option when urgent CABG needed and P2Y12 on board.
Aspirin	Do NOT hold	Irreversible COX-1	Continue through surgery. Discontinuation ↑ graft thrombosis risk.

Anticoagulation in ACS

Agent	Dose	Monitoring	ACS Context
UFH (PCI)	Bolus 70–100 U/kg (no GP IIb/IIIa) or 50–70 U/kg (with GP IIb/IIIa)	ACT 250–300s (or 200–250 with GPIIb/IIIa)	Standard for cath lab; can be reversed with protamine
UFH (medical)	60 U/kg bolus (max 4000) → 12 U/kg/hr (max 1000)	aPTT 1.5–2.5× control (60–80s)	NSTEMI medical management or post-fibrinolysis
Enoxaparin	1 mg/kg SC q12h 0.75 mg/kg q12h if ≥75 1 mg/kg q24h if CrCl <30	Anti-Xa if obese/renal	Can use through PCI (no switch to UFH if last dose <8h + 0.3 mg/kg IV bolus)
Bivalirudin	0.75 mg/kg bolus → 1.75 mg/kg/hr	ACT	Alternative for PCI; lower bleed risk but ↑ acute stent thrombosis. Preferred in HIT.
Fondaparinux	2.5 mg SC daily	None needed	NSTEMI medical Rx only (OASIS-5). CI for PCI — catheter thrombosis risk; add UFH if going to cath.

UFH Drip Protocol — ACS

Weight-based dosing with aPTT-guided titration. Goal aPTT: 60–80 seconds (1.5–2.5× control).

Initial Dosing

Bolus

60 U/kg

Maximum 4,000 units. Round to nearest 100.

Infusion

12 U/kg/hr

Maximum 1,000 U/hr. Check aPTT at 6 hours.

First aPTT

6 hours post-bolus

Then q6h until 2 consecutive in range; then q12–24h.

Platelet Monitoring

CBC q48h

HIT screen (4T score) if platelets drop ≥50% or to <150K. Send PF4 antibody.

aPTT Titration Table

aPTT (seconds)	Bolus	Rate Change	Repeat aPTT
<40	60 U/kg (max 4000)	↑ 4 U/kg/hr	6 hours
40–59	None	↑ 2 U/kg/hr	6 hours
60–80 ✓ Goal	None	No change	6h → then q12–24h
81–100	None	↓ 2 U/kg/hr	6 hours
101–120	None	↓ 3 U/kg/hr	6 hours
>120	Hold 1 hour	↓ 4 U/kg/hr	6 hours after restart

Post-PCI & Discharge Checklist

Standard post-procedure orders and discharge medications for ACS patients.

Immediate Post-PCI (0–24h)

Item	Detail
Sheath management	Remove per institutional protocol; manual pressure or closure device. Bed rest per access site (radial: 2h, femoral: 4–6h).
Anticoagulation	Discontinue UFH/bivalirudin post-PCI (routine cases). Do NOT continue drip unless indication (LV thrombus, extensive anterior MI, mechanical complication).
DAPT	Confirm loading doses given. Start maintenance: ASA 81mg + ticagrelor 90mg BID (or clopidogrel 75mg daily).
Monitoring	Serial ECG × 3 (post-PCI, 6h, 24h). Troponin q8h until trending down. Telemetry × 48h minimum (ACS).
Access site	Neurovascular checks q15min × 1h, q30min × 2h, then q4h. Watch for hematoma, pseudoaneurysm, retroperitoneal bleed (femoral).
Fluids / Renal	NS at 1 mL/kg/h × 12h post-contrast. BMP at 24–48h. Hold metformin 48h if CrCl concern.

Discharge Medications (ABCDE)

Class	Standard Order	Key Notes
Antiplatelet	ASA 81mg + P2Y12 daily	Ticagrelor preferred; counsel on not exceeding ASA 100mg; 12-month DAPT minimum post-ACS
Beta-blocker	Metoprolol succinate or carvedilol	Start within 24h if hemodynamically stable; target HR 55–65. CI: cardiogenic shock, high-degree AV block.
Cholesterol (statin)	Atorvastatin 80mg or rosuvastatin 40mg	High-intensity mandatory. No need for baseline lipid panel to start. Add ezetimibe if LDL >70 at f/u.
Diabetes / Dual Rx	SGLT2i if EF ≤40% or DM; ACEi/ARB for all post-MI	Ramipril/lisinopril within 24h if anterior MI, EF ≤40%, HF, HTN, DM. SGLT2i: dapagliflozin/empagliflozin.
Education	Cardiac rehab referral	Phase II cardiac rehab: 36 sessions. ↓ mortality 26% (Cochrane). NNT 37 to prevent 1 death. Counsel smoking cessation.