From the Guidelines
Nitroglycerin is contraindicated in inferior ST-elevation myocardial infarction (STEMI) because it can cause dangerous hypotension and worsen the patient's condition, as evidenced by the 2013 ACCF/AHA guideline for the management of ST-elevation myocardial infarction 1. Inferior STEMIs typically involve the right coronary artery, which often supplies the right ventricle. When the right ventricle is damaged in an inferior STEMI, it becomes dependent on adequate preload (blood returning to the heart) to maintain cardiac output. Nitroglycerin is a vasodilator that reduces preload by dilating veins, decreasing blood return to the heart. In patients with right ventricular involvement, this reduction in preload can precipitate profound hypotension, leading to decreased coronary perfusion and potentially worsening myocardial ischemia. Key considerations for the use of nitroglycerin in STEMI patients include:
- Avoiding its use in patients with hypotension, marked bradycardia or tachycardia, RV infarction, or 5phosphodiesterase inhibitor use within the previous 24 to 48 hours, as stated in the 2013 ACCF/AHA guideline 1.
- Obtaining a right-sided ECG to rule out right ventricular involvement before administering nitroglycerin to any STEMI patient, as suggested by the 2010 American Heart Association guidelines for cardiopulmonary resuscitation and emergency cardiovascular care 1.
- Focusing on maintaining adequate preload with IV fluids, treating pain with opioid analgesics like morphine, and proceeding with primary percutaneous coronary intervention as the definitive treatment, if right ventricular infarction is present or strongly suspected in an inferior STEMI.
From the FDA Drug Label
CONTRAINDICATIONS Nitroglycerin sublingual tablets are contraindicated in patients who are allergic to it. Sublingual nitroglycerin therapy is contraindicated in patients with early myocardial infarction, severe anemia, increased intracranial pressure, and those with a known hypersensitivity to nitroglycerin. WARNINGS The benefits of sublingual nitroglycerin in patients with acute myocardial infarction or congestive heart failure have not been established. If one elects to use nitroglycerin in these conditions, careful clinical or hemodynamic monitoring must be used because of the possibility of hypotension and tachycardia.
Nitroglycerin is contraindicated in an inferior STEMI due to the risk of hypotension and tachycardia associated with its use in patients with early myocardial infarction 2. The use of nitroglycerin in these conditions requires careful clinical or hemodynamic monitoring 2. Key points to consider include:
- Contraindication in patients with early myocardial infarction
- Risk of hypotension and tachycardia
- Need for careful monitoring if used in these conditions 2, 2
From the Research
Nitro Contraindication in Inferior STEMI
- The contraindication of nitroglycerin in inferior STEMI is thought to be due to the risk of developing hypotension, particularly in patients with right ventricular infarction 3.
- However, a study found that nitroglycerin administration to patients with inferior STEMI is not associated with a higher rate of hypotension compared to patients with STEMI in other territories 3.
- Another study suggested that the contraindication of nitrates in right ventricular myocardial infarction is not supported by evidence, and nitrates may be a reasonable treatment modality to consider during RVMI 4.
- The safety and effectiveness of field nitroglycerin in patients with suspected STEMI have been evaluated, and the results showed that field nitroglycerin did not result in a clinically significant decrease in blood pressure when compared with patients who did not receive nitroglycerin 5.
- The pathophysiology, clinical implications, and management of right ventricular myocardial infarction have been reviewed, highlighting the importance of identifying specific clinical signs and symptoms, initiating resuscitation, and commencing reperfusion therapy 6.
- It is worth noting that one of the studies provided is not relevant to the topic of nitro contraindication in inferior STEMI, as it discusses implant placement and guided tissue regeneration in a patient with congenital vitamin D-resistant rickets 7.