What is the NPO (nil per os) requirement before a coronary angiogram?

NPO Requirements Before Coronary Angiography

Patients undergoing coronary angiography do not need to be fasted for 6 hours prior to the procedure, and a shorter fasting period of 2 hours is reasonable and may improve patient satisfaction without increasing complications. 1

Evidence-Based Recommendations

The traditional practice of keeping patients nil per os (NPO) for extended periods before coronary angiography lacks strong evidence-based support. Recent research challenges this convention:

• The CORO-NF randomized pragmatic study demonstrated that reducing minimum fasting duration to 2 hours before coronary angiography:

  • Significantly improved patient satisfaction scores (4.2 ± 0.7 vs 2.9 ± 1.2, P < .001)
  • Did not increase peri- or post-procedural complications
  • Did not result in any food ingestion-related adverse events 1

• A retrospective analysis of 1,916 PCI procedures showed that patients who were not kept NPO prior to coronary procedures experienced:

  • No emergency endotracheal intubation requirements
  • No occurrences of aspiration pneumonia
  • 95% technical success rate 2

Practical NPO Guidelines for Coronary Angiography

Based on the most current evidence:

1. For liquids: Restrict clear liquids for 2 hours before the procedure
2. For solids: Light meals may be permitted up to 2-4 hours before the procedure

Special Considerations

Urgent/Emergent Procedures

For patients requiring immediate coronary angiography in acute settings (such as STEMI or cardiogenic shock), NPO status should not delay the procedure:

• The American College of Cardiology/American Heart Association guidelines recommend immediate coronary angiography for:
  • Patients with STEMI who are candidates for primary PCI 3
  • Patients with severe heart failure or cardiogenic shock who are suitable candidates for revascularization 3

Post-Fibrinolytic Therapy

For patients who received fibrinolytic therapy:

• Coronary angiography should not be performed within the first 2-3 hours after administration of fibrinolytic therapy 3
• Angiography is reasonable between 3-24 hours after successful fibrinolysis 3

Common Pitfalls to Avoid

1. Unnecessary prolonged fasting: Extended NPO periods can lead to dehydration, which may increase the risk of contrast-induced nephropathy, particularly in patients with pre-existing renal impairment

2. Delaying urgent procedures: For acute coronary syndromes requiring immediate intervention, NPO status should not delay life-saving procedures

3. Inadequate hydration: Patients should receive adequate preparatory hydration before procedures with contrast media to reduce the risk of contrast-induced nephropathy 3

Conclusion

The traditional practice of extended fasting before coronary angiography is not supported by current evidence. A shorter fasting period of 2 hours appears to be safe and improves patient satisfaction. For urgent/emergent cases, the procedure should not be delayed due to NPO status concerns.