What is the initial management for a patient with an inferior wall Non-ST-Elevation Myocardial Infarction (NSTEMI) presenting with chest pain, focusing on blood pressure and rate control?

Initial Management of Inferior Wall NSTEMI with Focus on Chest Pain, Blood Pressure, and Rate Control

For patients with inferior wall NSTEMI, initial management should include sublingual nitroglycerin for chest pain, oral beta-blockers for rate and blood pressure control within 24 hours (if no contraindications), and continuous ECG monitoring with bed rest. 1

Step-by-Step Management Algorithm

Immediate Interventions

1. Continuous ECG monitoring with bed/chair rest 1
2. Oxygen therapy:
   • Administer if arterial saturation <90% or respiratory distress 1
   • Reasonable to give to all patients during first 6 hours after presentation 1

Chest Pain Management

1. Sublingual nitroglycerin:

   • 0.4 mg every 5 minutes for a total of 3 doses 1
   • Assess need for IV nitroglycerin after initial doses
   • IV nitroglycerin indicated for first 48 hours for persistent ischemia, hypertension, or heart failure 1

2. Morphine sulfate:

   • Reasonable to administer IV if chest pain persists despite nitroglycerin 1
   • Typical dosing: 2-4 mg IV with increments of 2-8 mg repeated at 5-15 minute intervals 1

Blood Pressure Control

1. For hypertension:

   • IV nitroglycerin for first 48 hours 1
   • IV beta-blockers reasonable at presentation for hypertension control 1

2. Contraindications to nitrates:

   • Systolic BP <90 mmHg or ≥30 mmHg below baseline
   • Severe bradycardia (<50 bpm)
   • Tachycardia (>100 bpm) without heart failure
   • Right ventricular infarction
   • Recent use of phosphodiesterase inhibitors (sildenafil within 24h, tadalafil within 48h) 1

Heart Rate Control

1. Beta-blockers:

   • Oral beta-blockers within first 24 hours 1
   • IV beta-blockers reasonable for hypertension control 1

2. When beta-blockers are contraindicated:

   • Non-dihydropyridine calcium channel blockers (verapamil or diltiazem) as initial therapy 1
   • Only if no significant LV dysfunction or other contraindications 1

3. Contraindications to beta-blockers:

   • Signs of heart failure
   • Evidence of low-output state
   • Increased risk for cardiogenic shock*
   • PR interval >0.24 seconds
   • Second or third-degree heart block
   • Active asthma or reactive airway disease 1

Additional Important Therapies

1. Antiplatelet therapy:

   • Aspirin 162-325 mg (non-enteric coated for rapid absorption) 1

2. ACE inhibitors:

   • Administer orally within first 24 hours if pulmonary congestion or LVEF ≤0.40 1
   • Can be useful in all patients without contraindications 1

3. Angiotensin receptor blockers:

   • For patients intolerant to ACE inhibitors with heart failure signs or LVEF ≤0.40 1

Special Considerations for Inferior Wall NSTEMI

Inferior wall infarctions may involve the right ventricle, requiring careful monitoring for:

• Hypotension after nitrate administration 2
• Bradyarrhythmias requiring closer heart rate monitoring
• Need for adequate preload maintenance

Pitfalls to Avoid

1. Do not administer nitrates to patients with:

   • Right ventricular infarction (often associated with inferior MI)
   • Hypotension (SBP <90 mmHg)
   • Recent use of phosphodiesterase inhibitors 1

2. Do not administer IV beta-blockers to patients with:

   • Signs of heart failure
   • Evidence of low-output state
   • Risk factors for cardiogenic shock* 1

3. Do not administer immediate-release dihydropyridine calcium channel blockers without adequate beta blockade 1

4. Do not administer NSAIDs (except aspirin) due to increased risks of mortality, reinfarction, hypertension, heart failure, and myocardial rupture 1

*Risk factors for cardiogenic shock: age >70 years, systolic BP <120 mmHg, sinus tachycardia >110 bpm or heart rate <60 bpm, increased time since symptom onset 1