Are nitrates contraindicated in any other ST-Elevation Myocardial Infarction (STEMI) patients?

Contraindications for Nitrates in STEMI

Nitrates are contraindicated in STEMI patients with hypotension (SBP <90 mm Hg or ≥30 mm Hg below baseline), extreme bradycardia (<50 bpm), tachycardia in the absence of heart failure (>100 bpm), right ventricular infarction, and recent use of phosphodiesterase inhibitors. 1

Specific Contraindications

Hemodynamic Contraindications

• Hypotension: SBP <90 mm Hg or ≥30 mm Hg below baseline 1
• Bradycardia: Heart rate <50 bpm 1
• Tachycardia: Heart rate >100 bpm in the absence of heart failure 1

Anatomical Contraindications

• Right ventricular infarction: Nitrates can cause severe hypotension in these patients due to their dependence on adequate preload 1
  • Caution is advised in patients with known inferior wall STEMI, and a right-sided ECG should be performed to evaluate for RV involvement 1

Medication Interactions

• PDE-5 inhibitors: Nitrates should not be administered to patients who have taken:
  • Sildenafil or vardenafil within the last 24 hours 1, 2
  • Tadalafil within the last 48 hours 1, 2
• Riociguat: Concomitant use with soluble guanylate cyclase stimulators can cause profound hypotension 2

Special Considerations

Inferior Wall STEMI

Patients with inferior STEMI require special attention because:

• They have a higher likelihood of right ventricular involvement 1
• A right-sided ECG should be performed before administering nitrates to these patients 1
• If RV involvement is confirmed, nitrates should be avoided as these patients require adequate RV preload 1

Aortic Stenosis

While traditionally considered a relative contraindication, recent evidence suggests:

• Cautious use of nitrates may be considered in patients with moderate or severe aortic stenosis presenting with acute pulmonary edema 3
• However, these patients should be monitored closely as they may have a higher risk of sustained hypotension 3

Clinical Decision Making

When evaluating a STEMI patient for nitrate therapy:

1. Check blood pressure and heart rate
2. Determine infarct location (especially for inferior STEMI)
3. Perform right-sided ECG if inferior STEMI is suspected
4. Review medication history for PDE-5 inhibitors
5. Consider alternative therapies for pain control if nitrates are contraindicated:
   • Morphine is the preferred analgesic for patients with STEMI when nitrates are contraindicated 1

Monitoring During Nitrate Administration

For STEMI patients receiving nitrates:

• Monitor blood pressure frequently
• Discontinue nitrates if systolic BP drops below 90 mmHg
• Be prepared to administer volume expansion if hypotension occurs
• Watch for signs of decreased cardiac output, especially in patients with inferior wall STEMI

Remember that while nitrates can provide symptomatic relief, they have not been shown to reduce mortality in acute coronary syndromes 4. Therefore, they should not be prioritized over therapies with proven mortality benefits such as reperfusion strategies, antiplatelet agents, and beta-blockers.