In a patient with non‑ST‑segment elevation myocardial infarction and hypotension (blood pressure ~90/60 mmHg), what are the guidelines for using isosorbide dinitrate (Isoket)?

Isoket (Isosorbide Dinitrate) is Contraindicated in NSTEMI with Blood Pressure 90/60 mmHg

Nitrates should NOT be administered to NSTEMI patients with systolic blood pressure less than 90 mm Hg or ≥30 mm Hg below baseline. 1 This is a Class III recommendation (harm) with Level of Evidence C from ACC/AHA guidelines, meaning nitrates are contraindicated in your clinical scenario.

Why Nitrates Are Contraindicated at This Blood Pressure

The absolute contraindication exists because:

• Systolic BP <90 mmHg is an explicit contraindication to all forms of nitrates (sublingual, IV, or transdermal) in NSTEMI patients 1
• Nitrates cause venodilation and reduce preload, which will further decrease blood pressure and potentially precipitate cardiogenic shock 1
• The FDA drug label specifically warns that isosorbide dinitrate can cause severe hypotension and requires "careful clinical or hemodynamic monitoring to avoid the hazards of hypotension and tachycardia" 2

Additional Contraindications to Check

Before considering nitrates at any blood pressure, also exclude:

• Severe bradycardia (<50 bpm) or **tachycardia** (>100 bpm without heart failure) 1
• Right ventricular infarction (check for ST elevation in V4R) 1
• Phosphodiesterase inhibitor use within 24 hours (sildenafil/vardenafil) or 48 hours (tadalafil) 1, 3

What to Do Instead: Alternative Management Strategy

Immediate Priorities

1. Identify the cause of hypotension - Determine if this represents:

   • Cardiogenic shock (requiring inotropic support, possible IABP) 1
   • Right ventricular infarction (requires IV fluids, NOT nitrates) 1
   • Hypovolemia or other reversible causes

2. Administer aspirin immediately - Give 162-325 mg non-enteric coated, chewed 3, 4

3. Start antiplatelet therapy - Clopidogrel 300-600 mg loading dose (or ticagrelor 180 mg preferred) 3

4. Initiate anticoagulation - Unfractionated heparin, enoxaparin, or fondaparinux 3

Medications to AVOID in This Scenario

• Do NOT give beta-blockers - With BP 90/60 mmHg, the patient has increased risk for cardiogenic shock (systolic BP <120 mmHg is a risk factor) 1
• Do NOT give ACE inhibitors - Contraindicated when systolic BP <100 mmHg 1, 3
• Do NOT give IV nitrates - As discussed above 1

Pain Management Without Nitrates

• Morphine sulfate is reasonable for chest pain control: 2-4 mg IV with increments of 2-8 mg repeated at 5-15 minute intervals 1, 4
• Monitor blood pressure carefully as morphine can cause venodilation and modest BP reduction 1

Hemodynamic Support Considerations

If hypotension persists or worsens:

• Consider IABP counterpulsation - Reasonable for hemodynamic instability in NSTEMI patients before or after angiography 1, 3
• Evaluate for urgent/emergent cardiac catheterization - Hemodynamic instability is an indication for immediate invasive strategy 3

Critical Pitfall to Avoid

Never attempt to "start low and titrate" nitrates in a patient with baseline systolic BP <90 mmHg. The guideline threshold is absolute, not a suggestion for cautious dosing. Even small doses of nitrates can precipitate profound hypotension and cardiovascular collapse in this setting 1, 2.

When Nitrates Could Be Reconsidered

Only after blood pressure is stabilized to systolic BP ≥100 mmHg with appropriate interventions (fluids if appropriate, inotropes if needed, revascularization) could nitrates potentially be considered if ongoing ischemia persists 1. However, at that point, focus should be on definitive revascularization rather than medical management alone.