Can sorbitrate (isosorbide dinitrate) be given to a patient with CAD (Coronary Artery Disease) and ACS-IWMI (Acute Coronary Syndrome with Inferior Wall Myocardial Infarction) scheduled for CAG (Coronary Angiography)?

Sorbitrate (Isosorbide Dinitrate) Should Not Be Given to a Patient with ACS-IWMI

Sorbitrate (isosorbide dinitrate) should not be administered to a patient with CAD and ACS-IWMI who is planned for coronary angiography (CAG). The FDA drug label specifically warns against using isosorbide dinitrate in patients with acute myocardial infarction as its benefits have not been established in this setting 1.

Rationale for Avoiding Nitrates in Inferior Wall MI

1. Hemodynamic Concerns:

   • Patients with inferior wall MI often have right ventricular involvement, which makes them preload-dependent
   • Nitrates reduce preload through venodilation, which can cause:
     • Severe hypotension
     • Decreased cardiac output
     • Worsened hemodynamic status

2. Risk of Hypotension During CAG:

   • The patient is scheduled for coronary angiography
   • Nitrate-induced hypotension could complicate the procedure
   • The combination of contrast agents and nitrates may exacerbate hypotension

Evidence Supporting This Recommendation

The FDA drug label for isosorbide dinitrate clearly states that "the benefits of immediate-release oral isosorbide dinitrate in patients with acute myocardial infarction or congestive heart failure have not been established" 1. The label further warns that "if one elects to use isosorbide dinitrate in these conditions, careful clinical or hemodynamic monitoring must be used to avoid the hazards of hypotension and tachycardia" 1.

While isosorbide dinitrate can dilate coronary arteries and potentially improve blood flow to ischemic areas 2, 3, this benefit is outweighed by the risks in the setting of inferior wall MI. Research has shown that nitrates can cause significant reductions in pulmonary capillary wedge pressure (53% reduction) and mean arterial pressure (20% decrease) 2, which could be particularly dangerous in patients with right ventricular involvement.

Management Alternatives for ACS-IWMI

Instead of nitrates, focus on the following for this patient:

1. Antiplatelet Therapy:

   • Aspirin (loading dose 250-500mg, then 75-100mg daily)
   • P2Y12 inhibitor according to guidelines 4

2. Anticoagulation:

   • Unfractionated heparin (60-70 U/kg IV bolus, 12-15 U/kg/hr) or
   • Low molecular weight heparin (e.g., enoxaparin 1mg/kg SC every 12 hours) 4

3. Proceed with Planned CAG:

   • The European Society of Cardiology guidelines recommend an early invasive strategy (<24 hours) for patients with ACS 5
   • For patients with hemodynamic instability, immediate invasive strategy (<2 hours) is indicated 5

Monitoring and Precautions

• Continuous cardiac monitoring for arrhythmias
• Close blood pressure monitoring
• Assessment for signs of right ventricular involvement (JVD, Kussmaul's sign, hypotension)
• Adequate IV fluid support if right ventricular involvement is present

Conclusion

Sorbitrate (isosorbide dinitrate) should be avoided in this patient with ACS-IWMI who is planned for CAG due to the risk of severe hypotension and hemodynamic compromise. Focus instead on standard ACS management with antiplatelet therapy, anticoagulation, and timely coronary angiography.