How should a 50-year-old man with sinus bradycardia and ST-segment elevation in leads II, III, aVF, V1‑V3 be managed?

Management of 50-Year-Old Male with Bradycardia and ST Elevation in Inferior and Anterior Leads

This patient requires immediate activation of the cardiac catheterization laboratory for emergent coronary angiography and primary percutaneous coronary intervention (PCI), as the ECG pattern indicates ST-elevation myocardial infarction (STEMI) with extensive territory involvement. 1

Immediate Recognition and Diagnosis

This ECG pattern represents extensive STEMI involving both inferior and anterior territories, suggesting either:

• Proximal right coronary artery (RCA) occlusion with wraparound LAD territory 2, 3
• Multi-vessel occlusion 1
• Proximal left anterior descending (LAD) occlusion extending to inferior territory 4

The combination of ST elevation in leads II, III, aVF (inferior wall) plus V1-V3 (anterior/septal) indicates large territory at risk and high mortality without immediate reperfusion. 1

Critical Bradycardia Management

The sinus bradycardia requires immediate assessment for hemodynamic compromise:

• If the patient has hypotension, altered mental status, chest pain, or signs of shock: Administer intravenous atropine 0.5-1 mg immediately 1
• If atropine fails to restore adequate heart rate and perfusion: Prepare for temporary transcutaneous or transvenous pacing 1
• Avoid beta-blockers, calcium channel blockers, and amiodarone until bradycardia resolves, as these agents slow AV conduction 1

Sinus bradycardia is common in inferior STEMI due to increased vagal tone and ischemia of the SA node (supplied by RCA in 60% of patients). 1, 2 However, bradycardia with hemodynamic instability requires immediate positive chronotropic medication (atropine, epinephrine, or vasopressin). 1

Determining the Culprit Artery

Look for these specific ECG features to identify RCA versus LAD occlusion:

• ST elevation greater in lead III than lead II suggests RCA occlusion 2, 5, 3
• ST depression in leads I and aVL accompanying inferior ST elevation indicates RCA involvement 3
• ST elevation extending to V1 plus leads I and aVL with reciprocal depression in II, III, aVF indicates proximal LAD occlusion 4
• Immediately obtain right-sided leads V3R and V4R: ST elevation ≥1 mm in V4R confirms proximal RCA occlusion with right ventricular infarction 2, 5

Right ventricular involvement occurs with proximal RCA occlusion and carries high complication rates including complete heart block, cardiogenic shock, and arrhythmias. 2, 5

Immediate Medical Therapy (Pre-Catheterization)

Administer the following medications immediately while preparing for catheterization:

• Aspirin 150-300 mg orally or IV 1
• P2Y12 inhibitor: Ticagrelor 180 mg loading dose OR prasugrel 60 mg (if no contraindications) OR clopidogrel 600 mg if ticagrelor/prasugrel unavailable 1
• Anticoagulation: Unfractionated heparin 60-70 units/kg IV bolus (maximum 5000 units) followed by infusion, OR enoxaparin 0.5 mg/kg IV 1
• Morphine 4-8 mg IV for pain relief if needed 1

Critical caveat: If right ventricular infarction is confirmed (V4R elevation), avoid nitrates and aggressive fluid resuscitation—these patients are preload-dependent and nitrates cause profound hypotension. 5 Instead, give cautious fluid boluses (250-500 mL) only if hypotensive. 5

Reperfusion Strategy

Primary PCI is the preferred reperfusion strategy and should be performed within 90 minutes of first medical contact (door-to-balloon time). 1

If PCI is not available within 120 minutes of first medical contact AND symptom onset is <3 hours:

• Consider fibrinolytic therapy with tenecteplase (weight-based dosing) OR alteplase 1, 6
• However, given the extensive territory involvement and bradycardia suggesting possible high-degree AV block, immediate transfer to PCI-capable center is strongly preferred 1
• Fibrinolysis followed by immediate transfer for angiography (pharmacoinvasive strategy) is acceptable if primary PCI is delayed 1

Monitoring for Complications

This patient is at high risk for:

• Complete AV block: Occurs in 10-20% of inferior STEMI, especially with RCA occlusion 1
• Right ventricular failure and cardiogenic shock: If proximal RCA with RV involvement 2, 5
• Ventricular arrhythmias: Reperfusion arrhythmias (accelerated idioventricular rhythm, VT, VF) are common 6
• Mechanical complications: Free wall rupture, ventricular septal defect, papillary muscle rupture (rare but catastrophic) 1

Have atropine, temporary pacing equipment, defibrillator, and antiarrhythmic medications (amiodarone, lidocaine) immediately available. 1, 6

Common Pitfalls to Avoid

Do not delay catheterization to "rule out" non-cardiac causes (e.g., pancreatitis, pericarditis). While acute pancreatitis can mimic STEMI with ST elevation in inferior leads, 7 a 50-year-old male with this ECG pattern and appropriate clinical context (chest pain, dyspnea, diaphoresis) has STEMI until proven otherwise. 1, 8, 9

Do not dismiss this as "early repolarization" or "athlete's heart." While sinus bradycardia and ST elevation in V2-V4 can occur in athletes, 1, 10 the combination with inferior lead ST elevation in a 50-year-old is STEMI. 4, 2

Do not administer beta-blockers intravenously in the presence of bradycardia, hypotension, or heart failure—this is a Class III contraindication. 1

Do not use prophylactic antiarrhythmic drugs—this may be harmful. 1 Treat arrhythmias only if they occur and cause hemodynamic compromise.