What is the initial management for a patient diagnosed with Non-ST-Elevation Myocardial Infarction (NSTEMI)?

NSTEMI Diagnosis and Initial Management

For a patient diagnosed with NSTEMI, immediately place them on continuous ECG monitoring with defibrillator capacity, obtain a 12-lead ECG within 10 minutes, administer aspirin 162-325 mg (chewed), initiate dual antiplatelet therapy with a P2Y12 inhibitor, start anticoagulation, and perform risk stratification to determine timing of invasive coronary angiography. 1, 2, 3

Immediate Actions Upon Diagnosis

Monitoring and Environment

• Place the patient on continuous ECG monitoring with immediate defibrillator availability 1, 2
• Position emergency resuscitation equipment nearby 1
• Admit to a unit with continuous monitoring capability (chest pain unit, coronary care unit, or telemetry ward) 1

Oxygen Therapy

• Administer supplemental oxygen ONLY if arterial oxygen saturation is <90% or respiratory distress is present 1, 4, 2, 3
• Avoid routine oxygen therapy in patients with adequate saturation, as it provides no benefit 2, 3

Antiplatelet Therapy

Aspirin

• Administer aspirin 162-325 mg immediately (chewed for faster buccal absorption) 1, 2, 3
• Continue aspirin 75-100 mg daily indefinitely 2, 3

P2Y12 Inhibitor Selection

• Administer a P2Y12 inhibitor immediately upon diagnosis 2, 3
• For patients proceeding to PCI, ticagrelor or prasugrel are preferred over clopidogrel for higher-risk patients 2, 5
• Prasugrel dosing: 60 mg loading dose, then 10 mg daily 5
• Important timing consideration: In UA/NSTEMI patients, the loading dose should not be administered until coronary anatomy is established 5
• Continue dual antiplatelet therapy (aspirin plus P2Y12 inhibitor) for 12 months after PCI 3

Special Considerations for P2Y12 Inhibitors

• For patients weighing <60 kg on prasugrel, consider reducing maintenance dose to 5 mg daily due to increased bleeding risk 5
• Prasugrel is contraindicated in patients with prior stroke or TIA 5
• Discontinue clopidogrel 5-7 days before elective CABG 1

Anticoagulation Therapy

Initiate anticoagulation immediately with one of the following: 2, 3

• Unfractionated heparin: 60 U/kg IV bolus (maximum 4000 units), then 12 U/kg/hr infusion (maximum 1000 units/hr), adjusted to aPTT 1.5-2.5 times control 2
• Alternatively, low-molecular-weight heparin (enoxaparin) or fondaparinux may be used 1
• Continue anticoagulation for the duration of hospitalization, up to 8 days 1

Anti-Ischemic Therapy

Nitrates

• Administer sublingual nitroglycerin 0.4 mg every 5 minutes for up to 3 doses if ongoing ischemic chest pain 1, 2
• Initiate IV nitroglycerin starting at 10 mcg/min for persistent ischemia, heart failure, or hypertension, titrating to reduce blood pressure by 10-20% 1, 4, 2
• Contraindications: systolic BP <90 mmHg, suspected right ventricular infarction 2

Beta-Blockers

• Initiate oral beta-blocker therapy within the first 24 hours 1, 4, 2
• Avoid IV administration in patients with risk factors for cardiogenic shock 2
• Contraindications include: signs of heart failure, low-output state, heart rate <60 bpm, systolic BP <100 mmHg, PR interval >0.24 seconds, second or third degree heart block, active asthma or reactive airway disease 1, 4, 2

Morphine

• Administer morphine sulfate 2-4 mg IV with increments of 2-8 mg at 5-15 minute intervals for refractory chest pain uncontrolled by nitroglycerin 1, 4, 2

ACE Inhibitors/ARBs

• Administer an ACE inhibitor orally within the first 24 hours if pulmonary congestion or LVEF ≤0.40 is present, provided systolic BP ≥100 mmHg 4
• Use an ARB if the patient is intolerant of ACE inhibitors and has clinical or radiological signs of heart failure or LVEF ≤0.40 4

Risk Stratification and Timing of Invasive Strategy

Immediate Invasive Approach (Within 2 Hours)

Proceed to immediate coronary angiography for: 1, 2, 3

• Refractory angina despite maximal medical therapy
• Hemodynamic instability or cardiogenic shock
• Life-threatening ventricular arrhythmias
• Mechanical complications
• Recurrent angina with ST-segment depression ≥0.05 mV or new bundle branch block
• Acute heart failure

Early Invasive Strategy (Within 12-24 Hours)

Recommended for high-risk patients with: 2, 3

• GRACE score >140 or TIMI risk score >4
• Elevated troponin levels
• Dynamic ST-segment or T-wave changes
• LVEF <40%
• Diabetes mellitus
• Prior PCI or CABG

Conservative Strategy

• For low-risk patients without high-risk features, perform stress testing before discharge or within 72 hours as outpatient 1
• If stress testing reveals high-risk features, proceed to diagnostic angiography 1

Laboratory and Diagnostic Testing

Cardiac Biomarkers

• Obtain high-sensitivity cardiac troponin T or I at presentation 1
• Repeat troponin measurements at 1-3 hours if high-sensitivity assays are used, or at 3-6 hours with standard assays 1, 2
• Results should be available within 60 minutes 1
• Serial troponin measurements help distinguish NSTEMI (elevated biomarkers) from unstable angina (no biomarker elevation) 1

Additional Blood Work

• Serum creatinine, hemoglobin, hematocrit, platelet count, blood glucose 1
• INR in patients on warfarin 1
• Lipid profile should be assessed in the early phase of admission 1

Echocardiography

• Assess LV function with echocardiography during hospitalization to guide therapy with ACE inhibitors, beta-blockers, and aldosterone antagonists 4
• Consider immediate echocardiography in patients with ongoing chest pain and inconclusive ECG to exclude alternative diagnoses (pulmonary embolism, pericarditis, aortic dissection) 1

Critical Pitfalls to Avoid

• Never administer fibrinolytic therapy in NSTEMI patients—multiple trials demonstrated no benefit and potential harm 2
• Do not routinely use GP IIb/IIIa inhibitors upstream; reserve for high-risk patients undergoing PCI 2
• Do not delay angiography for "cooling off" period—early approach (median 2.4 hours) reduces death/MI compared to prolonged medical stabilization (median 86 hours) 2
• Avoid NSAIDs, as both COX-2 selective and nonselective agents increase mortality, reinfarction, and myocardial rupture risk 2
• Do not discontinue antiplatelet therapy prematurely, particularly in the first few weeks after ACS, as this increases risk of subsequent cardiovascular events 5

Distinguishing NSTEMI from Type 2 MI

NSTEMI typically results from acute atherothrombotic plaque rupture (Type 1 MI), but can also occur from oxygen supply-demand mismatch (Type 2 MI) 4, 6

• For Type 2 MI (e.g., secondary to respiratory failure, sepsis, anemia), an early invasive strategy is NOT automatically indicated 4
• Focus on treating the underlying precipitant rather than immediate coronary angiography 4
• Consider invasive approach only if evidence suggests concurrent Type 1 MI or patient becomes unstable with refractory ischemia 4

Ongoing Monitoring

• Monitor vital signs regularly 1
• Repeat ECG if symptoms recur or worsen 2
• In case of ongoing ischemia, place defibrillator patches until urgent revascularization is performed 1
• Hemodynamic monitoring for high-risk patients 2