When should nitroglycerin (nitrate) not be given to a patient with suspected or confirmed coronary artery disease (CAD)?

When Not to Give Nitroglycerin

Nitroglycerin should never be administered to patients with systolic blood pressure <90 mm Hg or ≥30 mm Hg below baseline, right ventricular infarction, recent phosphodiesterase-5 inhibitor use (within 24 hours for sildenafil/vardenafil or 48 hours for tadalafil), severe bradycardia (<50 bpm), or tachycardia (>100 bpm) without heart failure. 1, 2

Absolute Contraindications

Hypotension

• Do not give nitrates when systolic BP is <90 mm Hg or has dropped ≥30 mm Hg below the patient's baseline, as nitrate-induced vasodilation can precipitate cardiovascular collapse in already hypotensive patients 1, 2
• This threshold applies to all forms of coronary artery disease including STEMI, NSTEMI, and unstable angina 1

Right Ventricular Infarction

• Nitrates must be avoided in suspected or confirmed right ventricular infarction, as these patients are critically preload-dependent and nitrate-induced venous dilation causes catastrophic hemodynamic compromise 1, 2
• Always obtain a right-sided ECG in all patients with inferior wall STEMI before administering nitroglycerin, as up to 50% involve the right ventricle 2
• Use nitrates with extreme caution, if at all, in inferior MI even without confirmed RV involvement 1

Phosphodiesterase-5 Inhibitor Use

• Absolutely contraindicated within 24 hours of sildenafil or vardenafil use, or within 48 hours of tadalafil use, due to potentiation of severe hypotension that has been associated with myocardial infarction and death 1, 2, 3
• Healthcare providers must specifically ask about erectile dysfunction medications including VIAGRA, CIALIS, and LEVITRA in all patients 2, 3
• The suitable time for nitrate administration after vardenafil remains undetermined 1

Heart Rate Abnormalities

• Do not administer nitrates with severe bradycardia (<50 bpm), as nitrates can worsen bradycardia and further reduce cardiac output 1, 2
• Avoid nitrates with tachycardia (>100 bpm) in the absence of symptomatic heart failure, as this represents a Class III contraindication 1, 2

Severe Valvular Stenosis

• Nitrates are contraindicated in severe mitral or aortic stenosis, as these patients have fixed cardiac output that relies on maintaining adequate preload 4
• Nitrate-induced preload reduction is particularly dangerous when cardiac output depends on adequate left ventricular filling across an already narrowed valve 4
• In mitral stenosis specifically, nitrates can precipitate cardiovascular collapse by reducing already compromised cardiac output 4

Additional Contraindications from FDA Labeling

• Do not use in patients with very recent heart attack, severe anemia, or increased intracranial pressure 3
• Avoid concurrent use with guanylate cyclase stimulators (including riociguat for pulmonary arterial hypertension), as this leads to extreme blood pressure lowering 3

Critical Clinical Pitfalls to Avoid

Failure to Screen for PDE-5 Inhibitors

• This is the most common and dangerous oversight—always specifically ask about sildenafil, tadalafil, and vardenafil use in the preceding 24-48 hours 2

Administering Nitrates to Inferior STEMI Without Right-Sided ECG

• Up to 50% of inferior MIs involve the right ventricle, making this a critical assessment before nitrate administration 2

Ignoring Relative Hypotension

• Even if systolic BP is technically >90 mm Hg, a drop of ≥30 mm Hg from baseline represents a contraindication 1

Using Nitrates in Valvular Disease

• Failing to recognize severe stenotic valve disease as a contraindication can lead to hemodynamic collapse 4

Alternative Management Strategies

For Ischemic Chest Pain When Nitrates Are Contraindicated

• Morphine sulfate (2-4 mg IV with increments of 2-8 mg repeated at 5-15 minute intervals) is the analgesic of choice, as it relieves pain without profound preload reduction 1, 4
• Aspirin 162-325 mg should be administered if acute coronary syndrome is suspected 1, 4
• Beta-blockers can be considered for hypertension or tachycardia if no contraindications exist 4

For Pulmonary Congestion in Valvular Disease

• Loop diuretics are indicated to relieve congestion in mitral stenosis, not nitrates 4
• High-flow oxygen should be given if oxygen saturation is <90% 4
• Non-invasive ventilation (CPAP) may be considered if respiratory rate exceeds 20 breaths/min 4

Special Consideration for RV Infarction

• If hypotension develops after inadvertent nitrate administration, immediately discontinue the drug, elevate legs, administer rapid IV fluids, and give atropine as needed 1