How should I administer glyceryl trinitrate for chest pain and manage new‑onset atrial fibrillation with rapid ventricular response (110 bpm) in a patient with a blood pressure of 130/60 mmHg?

Management of GTN in Chest Pain with New-Onset AF with RVR

Glyceryl trinitrate (GTN) is contraindicated in this patient with new-onset atrial fibrillation at a rate of 110 bpm, as the American Heart Association explicitly states that nitrates should not be used in patients with tachycardia in the absence of heart failure when heart rate exceeds 100 bpm. 1

Primary Contraindication

• The 2015 AHA guidelines clearly state that nitrates are contraindicated in patients with tachycardia >100 bpm in the absence of heart failure, making GTN inappropriate for this patient with AF at 110 bpm 1
• While the blood pressure of 130/60 mmHg is technically above the absolute contraindication threshold of <90 mmHg systolic, the combination of tachycardia and relatively low diastolic pressure (60 mmHg) creates additional hemodynamic risk 1

Immediate Management Priorities

Focus on rate control of the atrial fibrillation first, then reassess chest pain management:

• Intravenous diltiazem is indicated for temporary control of rapid ventricular rate in atrial fibrillation, and the FDA label confirms it is effective in reducing heart rate by at least 20% in 95% of patients, with response occurring within 3 minutes 2
• Continuous ECG monitoring and frequent blood pressure measurement are mandatory, with defibrillator and emergency equipment readily available 2
• Ensure the patient does not have WPW syndrome or accessory bypass tract before administering diltiazem, as this is an absolute contraindication 2

Alternative Anti-Ischemic Management

Once rate control is achieved and heart rate drops below 100 bpm, GTN may be reconsidered if chest pain persists:

• If the heart rate is successfully reduced to <100 bpm with diltiazem and systolic BP remains ≥90 mmHg, sublingual GTN 0.3-0.4 mg may then be administered, repeated every 5 minutes for up to 3 doses 1, 3
• Intravenous morphine sulfate is the preferred analgesic for chest pain unresponsive to initial measures, though use with caution as it has been associated with increased mortality in some registries 1, 4

If GTN remains contraindicated due to persistent tachycardia or hemodynamic concerns:

• Oral beta-blockers should be considered within the first 24 hours once the patient is stabilized, provided there are no contraindications such as heart failure or risk of cardiogenic shock 1, 4
• The diltiazem infusion itself provides anti-ischemic benefit through rate control and may reduce myocardial oxygen demand sufficiently to relieve chest pain 2

Essential Concurrent Measures

Regardless of GTN administration:

• Administer 162-325 mg non-enteric-coated aspirin (chewed) immediately unless there is true allergy or active GI bleeding 3, 4
• Obtain 12-lead ECG within 10 minutes to evaluate for STEMI or ischemic changes 3, 5
• Draw initial high-sensitivity troponin with repeat at 3-6 hours 3, 5
• Establish continuous cardiac monitoring 3

Critical Pitfalls to Avoid

• Do not use GTN as a diagnostic test – the European Society of Cardiology explicitly warns that nitroglycerin response "can be misleading" and should not distinguish cardiac from non-cardiac chest pain 3, 5
• Never administer immediate-release nifedipine without a beta-blocker, as this is contraindicated 4
• Avoid NSAIDs (except aspirin) due to increased risk of mortality, reinfarction, and myocardial rupture 1, 4
• Do not assume symptom relief from rate control alone excludes ACS – complete cardiac evaluation with serial troponins is mandatory regardless of symptom response 5

Hemodynamic Monitoring During Rate Control

• Hypotension may occur with diltiazem and can last 1-3 hours; 3.2% of patients require intervention such as IV fluids or Trendelenburg positioning 2
• Heart rate reduction typically lasts 1-3 hours after bolus dosing, with continuous infusion maintaining at least 20% reduction in 83% of patients 2
• If hypotension develops (SBP <90 mmHg), this creates an additional absolute contraindication to GTN 1