What premedication should be given to a patient scheduled for coronary angiography?

Premedication for Coronary Angiography (CAG)

Antiplatelet Therapy - The Essential Premedication

All patients scheduled for coronary angiography should receive aspirin 162-325 mg (non-enteric formulation for rapid buccal absorption) immediately, followed by 75-100 mg daily maintenance, unless already on chronic aspirin therapy. 1, 2

P2Y12 Inhibitor Strategy - Critical Decision Point

The timing of P2Y12 inhibitor administration depends entirely on your clinical scenario:

For STEMI patients going directly to primary PCI: Give a loading dose of ticagrelor 180 mg or clopidogrel 600 mg as early as possible before or at the time of the procedure. 2 Prasugrel 60 mg may be given promptly but no later than 1 hour after PCI once coronary anatomy is defined. 1

For NSTEMI/unstable angina with planned early invasive strategy: Administer clopidogrel 600 mg or ticagrelor 180 mg as early as possible before diagnostic angiography. 1 Alternatively, an IV GP IIb/IIIa inhibitor (eptifibatide or tirofiban preferred) can be given before the procedure for high-risk patients. 1

For stable CAD/elective diagnostic catheterization: Do NOT give any P2Y12 inhibitor before diagnostic angiography when coronary anatomy is unknown (Class III recommendation). 2 Wait until after angiography when anatomy is defined and PCI is planned, then give clopidogrel 600 mg at least 2 hours before PCI or prasugrel 60 mg promptly after the decision to proceed with PCI. 2

The CABG Bleeding Risk Consideration

This is a critical pitfall: If you give clopidogrel or prasugrel before knowing the anatomy and the patient requires urgent CABG, you create a 5-7 day delay (clopidogrel) or 7-day delay (prasugrel) for surgery due to excessive bleeding risk. 1, 2 The only exception is if you have very high probability of single-vessel disease requiring PCI and low probability of needing CABG. 2

Anticoagulation Therapy

Administer parenteral anticoagulation to all patients undergoing coronary angiography with planned or possible PCI. 2, 3 Choose one of the following:

• Unfractionated heparin: 70-100 U/kg IV bolus (50-70 U/kg if using GP IIb/IIIa inhibitor concurrently) 1, 3
• Enoxaparin: 0.5 mg/kg IV bolus 3
• Bivalirudin: 0.75 mg/kg IV bolus followed by 1.75 mg/kg/hr infusion during procedure 1

For NSTEMI patients already on anticoagulation therapy before arrival, continue the same agent through the procedure. 1

Anxiolysis/Sedation - NOT Routinely Recommended

Routine premedication with benzodiazepines (diazepam, chlorpheniramine) before coronary angiography is NOT recommended and provides no benefit. 4 A randomized controlled trial of 200 patients showed no difference in anxiety (59% vs 50%, p=0.2) or pain perception (31% vs 29%, p=0.75) between premedicated and non-premedicated groups. 4 Interestingly, local pain was actually MORE pronounced in premedicated patients (30% vs 16%, p=0.018). 4

If sedation is needed during the procedure (at operator's discretion for patient comfort), give midazolam IV in small increments:

• Initial dose: 0.5-1 mg IV over 2 minutes 5
• Wait 2+ minutes to evaluate effect 5
• Additional titration: 1 mg over 2 minutes if needed, waiting 2+ minutes between doses 5
• Total doses >3.5 mg rarely necessary 5
• Elderly/debilitated patients require 50% dose reduction 5

Anti-Ischemic Therapy for ACS Patients

For patients with ongoing ischemic symptoms:

• Sublingual nitroglycerin: 0.4 mg every 5 minutes for up to 3 doses 2
• IV nitroglycerin: Initiate if symptoms persist after sublingual doses 2
• Oral beta-blocker: Start within first 24 hours unless contraindicated (heart failure, low-output state, PR interval >0.24 seconds, heart rate <60 bpm, systolic BP <100 mmHg) 2
• Morphine sulfate IV: For uncontrolled ischemic chest pain despite nitroglycerin 2

Contrast Allergy Prophylaxis

While not explicitly addressed in the provided guidelines, standard practice for patients with prior contrast reactions includes premedication with corticosteroids and antihistamines 12-24 hours before the procedure, though this was not covered in the evidence provided.

Critical Medications to AVOID

NSAIDs (except aspirin) are absolutely contraindicated during hospitalization for ACS patients due to increased risks of mortality, reinfarction, hypertension, heart failure, and myocardial rupture. 2

Summary Algorithm

1. Give aspirin immediately (162-325 mg loading, then 75-100 mg daily) 1
2. Determine clinical scenario:
   • STEMI → Give P2Y12 inhibitor immediately 2
   • NSTEMI/high-risk → Give P2Y12 inhibitor or GP IIb/IIIa before angiography 1
   • Stable CAD → Wait until after angiography to give P2Y12 inhibitor 2
3. Start anticoagulation (UFH, enoxaparin, or bivalirudin) 1, 3
4. Do NOT give routine benzodiazepine premedication 4
5. Add anti-ischemic therapy if ACS with ongoing symptoms 2