What medications should be started during an acute coronary syndrome (ACS) workup?

Medications to Start During ACS Workup

During an acute coronary syndrome (ACS) workup, patients should immediately receive aspirin 150-300 mg (chewed if possible), anticoagulation with unfractionated heparin or low-molecular-weight heparin, a P2Y12 inhibitor (preferably ticagrelor or clopidogrel), and nitrates for ongoing pain. 1

Initial Pharmacological Management

Antiplatelet Therapy

1. Aspirin

   • Loading dose: 162-325 mg orally (non-enteric coated, chewed when possible) 1
   • Maintenance: 75-100 mg daily 1
   • Should be given immediately upon suspicion of ACS 1
   • For aspirin-allergic patients: Use clopidogrel alone or consider aspirin desensitization 1

2. P2Y12 Inhibitor (in addition to aspirin)

   • Ticagrelor: 180 mg loading dose, then 90 mg twice daily (preferred in NSTE-ACS) 1
   • Clopidogrel: 300-600 mg loading dose, then 75 mg daily 1, 2
     • Use when ticagrelor is not available or contraindicated 1
   • Prasugrel: 60 mg loading dose, then 10 mg daily (only after coronary anatomy is known) 1
     • Not recommended before coronary anatomy is known 1

Anticoagulation

1. Unfractionated Heparin (UFH)

   • IV bolus 60-70 IU/kg (maximum 5000 IU) followed by infusion of 12-15 IU/kg/h 1
   • Target aPTT 1.5-2.5× control 1

2. Low-Molecular-Weight Heparin (LMWH)

   • Enoxaparin: 1 mg/kg subcutaneously twice daily 1
   • Consider in place of UFH 1

3. Fondaparinux

   • 2.5 mg subcutaneously daily 1
   • If using fondaparinux and proceeding to PCI, add UFH bolus (85 IU/kg) 1

4. Bivalirudin

   • May be considered as alternative to UFH (0.75 mg/kg bolus, followed by 1.75 mg/kg/h) 1
   • Only indicated for patients with planned invasive strategy 1

Anti-ischemic Therapy

1. Nitrates

   • Sublingual nitroglycerin: 0.4 mg every 5 minutes for up to 3 doses 1
   • IV nitroglycerin for persistent symptoms or hypertension 1
   • Avoid if systolic BP <90 mmHg or if PDE5 inhibitors used recently 1

2. Beta-blockers

   • Oral beta-blockers should be started within the first 24 hours 1
   • Especially beneficial if tachycardic or hypertensive without signs of heart failure 1
   • IV beta-blockers can be used for persistent ischemia, tachycardia, or hypertension 1

3. Pain Management

   • Morphine: 2-4 mg IV, may repeat every 5-15 minutes (up to 10 mg) for refractory pain 1
   • Fentanyl: 25-50 μg IV as alternative 1
   • Caution: Opioids may delay absorption of oral P2Y12 inhibitors 1

Risk Stratification and Additional Medications

For high-risk patients (recurrent ischemia, elevated troponin, hemodynamic instability, major arrhythmias):

1. GP IIb/IIIa Inhibitors

   • Consider for bail-out situations (no-reflow or thrombotic complications during PCI) 1
   • Options include abciximab, tirofiban, or eptifibatide 1

2. Calcium Channel Blockers

   • Consider if beta-blockers are contraindicated or not tolerated 1

Common Pitfalls and Caveats

1. Aspirin Dosing: Initial high dose (162-325 mg) followed by lower maintenance dose (75-100 mg) provides optimal benefit with reduced bleeding risk 1

2. P2Y12 Inhibitor Selection:

   • Prasugrel should not be administered before coronary anatomy is known 1
   • Clopidogrel may have reduced effectiveness in CYP2C19 poor metabolizers 2

3. Anticoagulation Management:

   • Crossover between UFH and LMWH is not recommended 1
   • When using fondaparinux, supplemental UFH is needed during PCI 1

4. Nitrate Contraindications:

   • Avoid in right ventricular infarction
   • Do not use within 24-48 hours of PDE5 inhibitors 1

5. Opioid Considerations:

   • May delay absorption of oral P2Y12 inhibitors
   • Use only for refractory pain after maximizing anti-ischemic medications 1

By following this evidence-based approach to medication initiation during ACS workup, you can optimize outcomes by reducing mortality, preventing recurrent ischemic events, and improving quality of life for patients with suspected ACS.