What is the management for chest pain in a patient with Non-ST-Elevation Myocardial Infarction (NSTEMI)?

Management of Chest Pain in Admitted NSTEMI Patients

For an admitted NSTEMI patient with ongoing chest pain, immediately administer sublingual nitroglycerin 0.4 mg every 5 minutes for up to 3 doses, and if pain persists, initiate intravenous nitroglycerin for the first 48 hours while ensuring oral beta-blocker therapy is started within 24 hours unless contraindicated. 1, 2

Immediate Anti-Ischemic Therapy Algorithm

First-Line: Nitroglycerin

• Administer sublingual nitroglycerin 0.4 mg every 5 minutes for a total of 3 doses for ongoing ischemic chest discomfort 1, 2
• If chest pain persists after sublingual therapy, initiate intravenous nitroglycerin for the first 48 hours to treat persistent ischemia, heart failure, or hypertension 1, 2
• Intravenous nitroglycerin has proven effective even when pain is refractory to multiple sublingual doses 3, 4

Critical contraindications to nitrates:

• Systolic blood pressure <90 mmHg or ≥30 mmHg below baseline 1
• Recent phosphodiesterase inhibitor use: within 24 hours of sildenafil or vardenafil, or within 48 hours of tadalafil 1
• Severe bradycardia (<50 bpm) or tachycardia (>100 bpm) without symptomatic heart failure 1
• Right ventricular infarction 1

Second-Line: Morphine Sulfate

• If chest pain persists despite maximally tolerated nitroglycerin, administer morphine sulfate intravenously 1, 2
• The American Heart Association classifies this as Class IIb evidence (may be reasonable), so use morphine only after optimizing anti-ischemic medications 1
• Ensure additional therapy addresses the underlying ischemia when using morphine 1

Beta-Blocker Therapy Within 24 Hours

Initiate oral beta-blocker therapy within the first 24 hours unless the patient has any of the following contraindications 1, 2:

• Signs of heart failure 1
• Evidence of low-output state 1
• Increased risk for cardiogenic shock (age >70 years, systolic BP <120 mmHg, sinus tachycardia >110 bpm or heart rate <60 bpm, prolonged time since symptom onset) 1
• PR interval >0.24 seconds 1
• Second or third-degree heart block without a pacemaker 1
• Active asthma or reactive airway disease 1

Intravenous beta-blockers are potentially harmful when risk factors for shock are present and should be avoided 1

Alternative Anti-Ischemic Agents

Calcium Channel Blockers

If beta-blockers are contraindicated, unsuccessful, or cause unacceptable side effects:

• Administer nondihydropyridine calcium channel blockers (verapamil or diltiazem) for continuing or recurrent ischemia 1
• Ensure absence of clinically significant left ventricular dysfunction, increased risk for cardiogenic shock, PR interval >0.24 seconds, or second/third-degree AV block without pacemaker 1
• Immediate-release nifedipine is contraindicated in the absence of a beta-blocker 1

Long-Acting Agents for Refractory Pain

• Oral long-acting nondihydropyridine calcium channel blockers are reasonable for recurrent ischemia after beta-blockers and nitrates have been fully utilized 1

Essential Concurrent Therapies

ACE Inhibitors/ARBs

• Administer ACE inhibitor orally within the first 24 hours if pulmonary congestion is present or LVEF ≤0.40, provided systolic BP ≥100 mmHg 1, 2
• ACE inhibitors can also be useful in patients without pulmonary congestion or reduced LVEF 1
• Use angiotensin receptor blocker if ACE inhibitor intolerant with heart failure or LVEF <0.40 1

Antiplatelet Therapy

• Continue aspirin indefinitely 2
• Administer P2Y12 inhibitor (clopidogrel 300 mg loading dose in patients <75 years, 75 mg in patients ≥75 years, followed by 75 mg daily) 5
• The CURE trial demonstrated a 20% relative risk reduction in cardiovascular death, MI, or stroke with clopidogrel plus aspirin versus aspirin alone in NSTEMI patients 5

Anticoagulation

• Administer parenteral anticoagulation to all NSTEMI patients in addition to antiplatelet therapy 2
• Preferred agents include unfractionated heparin, enoxaparin, or fondaparinux 2
• Enoxaparin is highly recommended as the anticoagulant of choice in the pre-hospital and early hospital setting 1

Statin Therapy

• Initiate or continue high-intensity statin therapy in all patients with no contraindications 1

Critical Medications to Avoid

Discontinue NSAIDs (except aspirin) immediately due to increased risks of mortality, reinfarction, hypertension, heart failure, and myocardial rupture 1, 2

Monitoring and Environment

• Admit to a monitored unit with continuous ECG monitoring 2
• Ensure defibrillation equipment is immediately available 2
• Maintain bed/chair rest for at least 24 hours 2
• Administer supplemental oxygen only if arterial saturation is <90%, respiratory distress is present, or other high-risk features for hypoxemia exist 1, 2

Common Pitfalls to Avoid

1. Do not withhold beta-blockers based solely on age - the benefits extend across age groups when contraindications are absent 1
2. Do not use immediate-release dihydropyridine calcium channel blockers without adequate beta-blockade - this is associated with harm 1
3. Do not delay beta-blocker initiation beyond 24 hours in eligible patients - early administration improves outcomes 1, 2
4. Do not continue NSAIDs - these must be stopped at presentation 1
5. Do not give nitrates to patients who recently used phosphodiesterase inhibitors - this can cause life-threatening hypotension 1