Nitrates in RV MI

The belief that nitrates are contraindicated in RVMI is based largely on a single study from 1989 (Ferguson et al.). This was a retrospective analysis of patients with inferior MI, comparing those who developed marked hypotension (≥30 mmHg SBP drop) after nitrates (n=20) to those who did not (n=20). RVMI was defined by ST elevation ≥1 mm in ≥2 right precordial leads. They found that 15/20 hypotensive patients had RV involvement, while only 2/20 non-hypotensive patients did. This study concluded that nitrates in RVMI could cause profound hypotension by reducing right ventricular preload, leading to decreased cardiac output and hemodynamic collapse. This was incorporated into the AHA & ESC guidelines, advising caution in patients with suspected RV MI.

However there were significant limitations in the study:

1. Small sample size
2. Patients were not randomized, and no control group was established.
3. No standardization of nitro dose or route
4. No control for confounders - Did these patients receive IV fluids? Were they already hypotensive? Other medications (e.g., calcium channel blockers) were co-administered, potentially influencing results.
5. Hypotension was defined as a ≥30 mmHg drop in SBP with symptoms, but BP measurements were not standardized. Transient BP drops may have been misclassified as clinically significant.
6. Never replicated in larger studies

This systematic review and meta-analysis included five studies with a total of 1,113 patients evaluating the safety of nitroglycerin in inferior MI with or without RV involvement. Studies were included if they reported hemodynamic outcomes, adverse events, or mortality in patients receiving nitroglycerin. The primary outcome was the incidence of hypotension, while secondary outcomes included cardiac arrest, death, and other major adverse events.

Key Findings:

• No significant difference in cardiac arrest or mortality between RVMI and non-RVMI patients given nitroglycerin.
• Transient hypotension occurred but was manageable with fluids and positioning.
• No statistical increase in adverse events with 400 μg SL nitro in RVMI vs. other infarcts.
• Most cases of hypotension were mild and self-limited without long-term harm.
• Data on isolated RVMI remains limited, as most included patients had inferior MI with possible RV involvement.

Author Conclusion

The absolute contraindication of nitrates in RVMI is not supported by current evidence, as serious adverse events were not significantly increased. While caution is still warranted in hypotensive patients, nitroglycerin should not be reflexively withheld in suspected RVMI.

Limitations

While this systematic review challenges the absolute contraindication of nitrates in RVMI, there are important limitations to consider:

1. No Data on Isolated RVMI – All included studies involved combined inferior & RV MI. The safety of nitrates in isolated RVMI remains unclear.
2. Small RVMI Subgroups – While larger than Ferguson et al., the RVMI subgroups in these studies were still relatively small.
3. Variable Definitions of Hypotension – Some studies defined hypotension as SBP <100 mmHg, while others used <90 mmHg or a >30% drop, making adverse event comparisons inconsistent.
4. No Assessment of Clinical Benefits – The study focused on adverse events, not whether nitrates improve outcomes like pain relief, infarct size, or mortality.
5. Guidelines Haven’t Changed Yet – AHA & ESC still recommend caution with nitrates in RVMI.

Should we start giving nitrates to all RVMI patients? Not necessarily—here’s what you need to consider:

• If the patient is already hypotensive, avoid nitrates or proceed cautiously. If BP is stable or elevated, nitrates may be reasonable.
• If giving nitrates, start with 300–400 μg SL and monitor response. If transient hypotension occurs, it’s easily corrected with IV fluids.
• Right-Sided ECGs helps confirm RV involvement, though it shouldn’t delay critical treatment.
• No blanket rule should override patient-centered decision-making.

The absolute contraindication of nitrates in RVMI is not evidence-based. The fear of catastrophic hypotension is likely overstated, and in many cases, nitrates can be given safely. However, until guidelines formally change, clinical judgment remains key. Monitor patients closely and be prepared to manage transient BP drops.

🔗 Want to Read More?

• REBELEM:  Nitrates in Right Sided MIs?
• SGEM: Don’t Worry, Be Happy – The Safety of Nitroglycerin Administration in RVMI

• American Heart Association. (2025). 2025 ACC/AHA/ACEP/NAEMSP/SCAI guideline for the management of patients with acute coronary syndromes. Circulation, 2025, CIR.0000000000001309. https://doi.org/10.1161/CIR.0000000000001309
• Ferguson JJ, Diver DJ, Boldt M, Pasternak RC. Significance of nitroglycerin-induced hypotension with inferior wall acute myocardial infarction. Am J Cardiol. 1989 Aug 1;64(5):311-4. doi: 10.1016/0002-9149(89)90525-0. PMID: 2502902.
• Milne, K. (2024, January). SGEM #428: Don’t Worry, Be Happy – The Safety of Nitroglycerin Administration in RVMI. The Skeptics' Guide to Emergency Medicine (SGEM). https://thesgem.com/2024/01/sgem428-dont-worry-be-happy-the-safety-of-nitroglycerin-administration-in-rvmi/
• Salim Rezaie, "REBEL Cast Ep124: Nitrates in Right Sided MIs?", REBEL EM blog, March 18, 2024. Available at: https://rebelem.com/rebel-cast-ep124-nitrates-in-right-sided-mis/.
• Wilkinson-Stokes M, Betson J, Sawyer S. Adverse events from nitrate administration during right ventricular myocardial infarction: a systematic review and meta-analysis. Emerg Med J. 2023 Feb;40(2):108-113. doi: 10.1136/emermed-2021-212294. Epub 2022 Sep 30. PMID: 36180168.