What is high‑lateral ST‑segment elevation myocardial infarction (STEMI), including its definition, relevant anatomy and physiology, etiology and pathophysiology, signs and symptoms, typical cardiovascular intensive care unit (CVICU) presentation, diagnostic evaluation, medical and nursing management, immediate nursing priorities, potential complications, red‑flag findings, CVICU tips, expected clinical course, and prognostic indicators?

High Lateral ST-Elevation Myocardial Infarction (STEMI)

Definition

High lateral STEMI is characterized by ST-segment elevation ≥1 mm in leads I and aVL, often with reciprocal ST-depression in inferior leads (II, III, aVF), indicating acute transmural ischemia in the high lateral wall of the left ventricle supplied by the diagonal or high lateral circumflex branches. 1

The diagnosis requires characteristic symptoms of myocardial ischemia with persistent ST-elevation at the J-point in at least 2 contiguous leads, specifically ≥1 mm (0.1 mV) in leads I and aVL, with subsequent release of cardiac troponin above the 99th percentile upper reference limit 1. High lateral involvement may extend to leads V5-V6 when the lateral circumflex territory is affected 1.

Relevant Anatomy and Physiology

The high lateral wall is primarily supplied by diagonal branches of the left anterior descending artery (LAD) or high lateral branches of the left circumflex artery (LCx). 2

• Diagonal artery occlusion produces ST-elevation in leads I, aVL, and V2, typically sparing V3-V5, with 57-76% showing reciprocal ST-depression in inferior leads 2
• Proximal LAD occlusion involving diagonal branches produces more extensive ST-elevation extending to V1-V4 with reciprocal inferior changes 3, 2
• High lateral circumflex occlusion causes ST-elevation in I, aVL, V5-V6 without anterior lead involvement 1
• The high lateral wall contributes to left ventricular contractility and is particularly vulnerable to hemodynamic compromise when combined with anterior or inferior infarction 1

Etiology and Pathophysiology

High lateral STEMI results from acute thrombotic occlusion of a diagonal or high lateral circumflex branch, most commonly due to atherosclerotic plaque rupture, ulceration, fissuring, or erosion with intraluminal thrombus formation (Type 1 MI). 1, 4

• Plaque rupture triggers platelet aggregation and thrombus formation, causing complete or near-complete coronary occlusion 1, 5
• Transmural ischemia develops within minutes, progressing to irreversible myocardial necrosis if reperfusion is not achieved within 20-40 minutes 1, 4
• Risk factors include atherosclerosis, hypertension, diabetes, smoking, hyperlipidemia, and family history 4
• Less common etiologies include coronary spasm, spontaneous coronary artery dissection, coronary embolism, or Type 2 MI from supply-demand mismatch 1

Signs & Symptoms

Patients typically present with acute chest pain lasting >20 minutes, often radiating to the left arm, neck, or jaw, accompanied by diaphoresis, nausea, and dyspnea. 1

Classic presentation:

• Substernal chest pressure or tightness, described as "crushing" or "squeezing," not relieved by nitroglycerin 1
• Radiation to left arm, neck, jaw, or epigastrium 1
• Associated symptoms: diaphoresis, nausea/vomiting, dyspnea, lightheadedness 1
• Anxiety or sense of impending doom 1

Atypical presentations (more common in women, elderly, diabetics):

• Isolated dyspnea without chest pain 1
• Fatigue, weakness 1
• Syncope or presyncope 1
• Palpitations 1
• Epigastric discomfort mimicking gastrointestinal disease 1

Physical examination findings:

• Tachycardia or bradycardia (if conduction system involved) 1
• Hypertension (early) or hypotension (cardiogenic shock) 1
• Diaphoresis, pallor, cool extremities 1
• S4 gallop (decreased ventricular compliance) 1
• S3 gallop (ventricular dysfunction) 1
• New mitral regurgitation murmur (papillary muscle dysfunction) 1
• Pulmonary rales (left ventricular failure) 1

Typical CVICU Presentation

High lateral STEMI patients arrive in the CVICU post-primary PCI with continuous ECG monitoring, arterial line, and multiple IV access points, requiring intensive hemodynamic surveillance and arrhythmia monitoring. 1

Immediate post-PCI status:

• Femoral or radial arterial access site requiring immobilization and frequent neurovascular checks 1
• Continuous ECG telemetry for arrhythmia detection (ventricular tachycardia/fibrillation risk highest in first 48 hours) 1
• Arterial line for continuous blood pressure monitoring 3
• Dual antiplatelet therapy (aspirin + P2Y12 inhibitor) with bleeding precautions 1
• Parenteral anticoagulation (unfractionated heparin or bivalirudin) requiring monitoring 1, 3

Hemodynamic monitoring:

• Blood pressure monitoring every 15 minutes initially, then hourly if stable 1
• Continuous pulse oximetry (maintain SaO2 >90%) 1
• Urine output monitoring (target >0.5 mL/kg/hr) 1
• Assessment for cardiogenic shock (hypotension, cool extremities, altered mental status, oliguria) 1, 3

Common presentations:

• Chest pain requiring titrated nitroglycerin or morphine 1
• Anxiety requiring reassurance and possible anxiolysis 1
• Nausea/vomiting requiring antiemetics 1
• Recurrent chest pain suggesting reocclusion or incomplete revascularization 1

Diagnosis & Evaluation

Diagnosis requires 12-lead ECG within 10 minutes of first medical contact showing ST-elevation ≥1 mm in leads I and aVL, with cardiac troponin elevation confirming myocardial necrosis. 1

ECG criteria for high lateral STEMI:

• ST-elevation ≥1 mm (0.1 mV) in leads I and aVL in at least 2 contiguous leads 1
• Reciprocal ST-depression in inferior leads (II, III, aVF) present in 57-76% of cases 2
• ST-elevation may extend to V2 (diagonal occlusion) or V5-V6 (circumflex occlusion) 1, 2
• Critical pattern: ST-elevation in aVR + V1 with widespread ST-depression suggests left main or proximal multivessel disease requiring immediate catheterization 3

Cardiac biomarkers:

• Cardiac troponin I or T (preferred biomarker) with elevation above 99th percentile upper reference limit 1
• Serial troponin measurements showing rise and/or fall pattern 1
• CK-MB mass as alternative if troponin unavailable 1
• Peak troponin correlates with infarct size and prognosis 1

Coronary angiography:

• Immediate catheterization laboratory activation without waiting for troponin results 1, 3
• Identifies culprit lesion (diagonal, proximal LAD, or high lateral circumflex) 2
• TIMI flow grade assessment (0-3) guides intervention 2
• Evaluates for multivessel disease requiring staged revascularization 1

Echocardiography:

• Identifies regional wall motion abnormalities in high lateral segments 1, 2
• Assesses left ventricular ejection fraction (LVEF) for risk stratification 1
• Detects mechanical complications (papillary muscle rupture, ventricular septal defect, free wall rupture) 1
• Evaluates for right ventricular involvement if inferior extension present 1

Additional diagnostic tests:

• Chest X-ray to assess for pulmonary edema, cardiomegaly 1
• Complete blood count, comprehensive metabolic panel, coagulation studies 1
• Lipid panel (obtain before statin initiation) 1
• HbA1c for diabetes screening 1

Interventions/Treatments: Medical and Nursing Management

Primary percutaneous coronary intervention (PCI) within 90 minutes of first medical contact is the preferred reperfusion strategy, with immediate dual antiplatelet therapy, parenteral anticoagulation, and guideline-directed medical therapy. 1

Reperfusion Strategy

Primary PCI (preferred):

• Door-to-balloon time ≤90 minutes for patients presenting directly to PCI-capable facility 1
• First medical contact-to-device time ≤120 minutes for patients requiring transfer 1
• Drug-eluting stent preferred over bare-metal stent 1
• Avoid routine thrombus aspiration (no mortality benefit, increased stroke risk) 1
• Radial access preferred over femoral (reduced bleeding complications) in experienced operators 1

Fibrinolytic therapy (if PCI not available within 120 minutes):

• Tenecteplase (TNK-tPA) 30-50 mg IV bolus based on weight 1
• Administer within 30 minutes of STEMI diagnosis 1
• Transfer for angiography within 3-24 hours after fibrinolysis 1
• Contraindications: prior intracranial hemorrhage, ischemic stroke within 3 months, active bleeding, suspected aortic dissection 1

Antiplatelet Therapy

Immediate dual antiplatelet therapy:

• Aspirin 150-300 mg (non-enteric coating) loading dose, then 75-100 mg daily indefinitely 1, 3
• P2Y12 inhibitor (prasugrel 60 mg or ticagrelor 180 mg loading dose preferred over clopidogrel 600 mg) 1, 3
• Continue dual antiplatelet therapy for 12 months post-PCI 1
• Prasugrel contraindicated if prior stroke/TIA, age ≥75 years, weight <60 kg 1
• Ticagrelor preferred in patients with renal dysfunction 1

Anticoagulation

Parenteral anticoagulation during PCI:

• Unfractionated heparin 70-100 units/kg IV bolus (target ACT 250-350 seconds) 1, 3
• Bivalirudin 0.75 mg/kg IV bolus, then 1.75 mg/kg/hr infusion (alternative with lower bleeding risk) 1, 3
• Discontinue after successful PCI unless specific indication for continuation 1

Guideline-Directed Medical Therapy

Beta-blockers:

• Initiate oral beta-blocker within 24 hours if no contraindications (heart failure, cardiogenic shock, heart block, reactive airway disease) 1
• Metoprolol tartrate 25-50 mg PO every 6-12 hours, titrate to heart rate 50-60 bpm 1
• Continue indefinitely for mortality reduction 1

ACE inhibitors/ARBs:

• Initiate within 24 hours if LVEF ≤40%, heart failure, anterior MI, diabetes, or hypertension 1
• Lisinopril 2.5-5 mg PO daily, titrate to target dose 10-20 mg daily 1
• ARB (valsartan, losartan) if ACE inhibitor intolerant 1

Statins:

• High-intensity statin (atorvastatin 40-80 mg or rosuvastatin 20-40 mg) initiated immediately regardless of baseline LDL 1
• Target LDL <70 mg/dL, consider <55 mg/dL in very high-risk patients 1
• Continue indefinitely 1

Aldosterone antagonists:

• Eplerenone 25 mg PO daily if LVEF ≤40% and heart failure or diabetes, without significant renal dysfunction (creatinine <2.5 mg/dL men, <2.0 mg/dL women) or hyperkalemia 1
• Monitor potassium and renal function closely 1

Nitrates:

• Sublingual nitroglycerin 0.4 mg every 5 minutes × 3 doses for ongoing chest pain 1
• IV nitroglycerin 10-20 mcg/min for persistent ischemia, hypertension, or pulmonary edema (avoid if hypotension, right ventricular infarction, or recent phosphodiesterase inhibitor use) 1
• Do not use nitroglycerin as diagnostic test for chest pain 1

Oxygen therapy:

• Administer supplemental oxygen only if SaO2 <90% or respiratory distress 1
• Avoid routine oxygen in normoxemic patients (no benefit, potential harm) 1

Analgesia:

• Morphine sulfate 2-4 mg IV every 5-15 minutes for chest pain unrelieved by nitroglycerin 1
• Use cautiously (may delay P2Y12 inhibitor absorption and increase mortality in some studies) 1

Nursing Management

Continuous monitoring:

• ECG telemetry for arrhythmia detection (VT/VF risk highest first 48 hours) 1
• Vital signs every 15 minutes × 4, then hourly if stable 1
• Arterial line monitoring if hemodynamically unstable 3
• Pulse oximetry continuous (maintain SaO2 >90%) 1
• Urine output hourly (target >0.5 mL/kg/hr) 1

Access site management:

• Femoral access: maintain bed rest with leg immobilization for 4-6 hours post-sheath removal, assess for hematoma, pseudoaneurysm, retroperitoneal bleeding 1
• Radial access: assess radial pulse, hand perfusion, hematoma every 15 minutes × 4, then hourly 1
• Apply pressure dressing per protocol, monitor for bleeding 1

Medication administration:

• Ensure dual antiplatelet therapy given and documented 1
• Administer beta-blocker, ACE inhibitor, statin as ordered 1
• Titrate IV nitroglycerin for blood pressure and chest pain control 1
• Hold beta-blocker if heart rate <50 bpm or systolic BP <90 mmHg 1

Patient positioning:

• Head of bed elevated 30-45 degrees to reduce cardiac workload and improve respiratory mechanics 1
• Avoid Valsalva maneuvers (straining, bearing down) 1
• Assist with activities of daily living to minimize myocardial oxygen demand 1

Bowel regimen:

• Stool softener (docusate sodium 100 mg PO twice daily) to prevent constipation and Valsalva 1

Immediate Nursing Priorities

The immediate nursing priorities are continuous arrhythmia monitoring with defibrillator at bedside, hemodynamic stabilization, access site surveillance for bleeding, and serial assessment for recurrent ischemia or mechanical complications. 1

Priority 1: Arrhythmia surveillance and management

• Defibrillator immediately available at bedside 1
• Continuous ECG monitoring for ventricular arrhythmias (VT/VF most common first 48 hours) 1
• Recognize and treat life-threatening arrhythmias per ACLS protocols 1
• Monitor for bradycardia requiring atropine or temporary pacing 1
• Assess for heart block (especially if inferior extension present) 1

Priority 2: Hemodynamic monitoring and support

• Blood pressure monitoring every 15 minutes initially 1
• Assess for cardiogenic shock: systolic BP <90 mmHg, cool extremities, altered mental status, oliguria, elevated lactate 1, 3
• Recognize Killip classification: Class I (no heart failure), Class II (rales, S3), Class III (pulmonary edema), Class IV (cardiogenic shock) 1
• Notify physician immediately if systolic BP <90 mmHg or >180 mmHg 1
• Assess for right ventricular infarction if inferior extension: hypotension, clear lungs, elevated JVP 1

Priority 3: Access site assessment

• Assess femoral/radial access site every 15 minutes × 4, then hourly for first 24 hours 1
• Monitor for hematoma, active bleeding, pseudoaneurysm 1
• Assess distal pulses, capillary refill, temperature, sensation 1
• Measure thigh circumference if femoral access (detect retroperitoneal bleeding) 1
• Notify physician immediately if expanding hematoma, absent distal pulse, or hemodynamic instability 1

Priority 4: Recurrent ischemia assessment

• Assess chest pain character, intensity (0-10 scale), location, radiation, duration 1
• Obtain 12-lead ECG immediately if recurrent chest pain or ST-segment changes 1
• Administer sublingual nitroglycerin 0.4 mg every 5 minutes × 3 doses for chest pain 1
• Notify physician immediately if chest pain unrelieved by nitroglycerin (suggests reocclusion or incomplete revascularization) 1

Priority 5: Respiratory assessment

• Assess respiratory rate, effort, oxygen saturation 1
• Auscultate lung sounds for rales (pulmonary edema) 1
• Administer supplemental oxygen if SaO2 <90% 1
• Elevate head of bed 30-45 degrees 1
• Notify physician if respiratory distress, oxygen requirement increasing, or new pulmonary edema 1

Priority 6: Medication safety

• Verify dual antiplatelet therapy administered (aspirin + P2Y12 inhibitor) 1
• Hold beta-blocker if heart rate <50 bpm or systolic BP <90 mmHg 1
• Hold ACE inhibitor if systolic BP <90 mmHg 1
• Monitor for bleeding complications (antiplatelet + anticoagulation therapy) 1
• Assess for contraindications before administering nitroglycerin (right ventricular infarction, hypotension, recent sildenafil/tadalafil use) 1

Potential Complications

The most life-threatening complications are ventricular arrhythmias (VT/VF), cardiogenic shock, mechanical complications (papillary muscle rupture, ventricular septal defect, free wall rupture), and recurrent ischemia/reinfarction. 1

Arrhythmic Complications

Ventricular tachycardia/fibrillation:

• Most common cause of death in first 48 hours post-STEMI 1
• Risk factors: large infarct size, anterior location, LVEF <40%, heart failure 1
• Treatment: immediate defibrillation for VF, amiodarone or lidocaine for sustained VT 1
• Consider implantable cardioverter-defibrillator (ICD) if LVEF ≤35% persisting >40 days post-MI 1

Bradyarrhythmias and heart block:

• More common with inferior MI (right coronary artery supplies AV node) 1
• First-degree AV block: monitor, usually benign 1
• Second-degree Mobitz II or third-degree AV block: temporary pacing indicated 1
• Atropine 0.5 mg IV for symptomatic bradycardia 1

Atrial fibrillation:

• Occurs in 10-20% of STEMI patients 1
• Associated with larger infarct size, heart failure, increased mortality 1
• Treatment: rate control with beta-blockers, anticoagulation if CHA2DS2-VASc ≥2 1

Mechanical Complications

Papillary muscle rupture:

• Occurs 2-7 days post-MI, presents with acute severe mitral regurgitation 1
• Clinical presentation: sudden pulmonary edema, hypotension, new holosystolic murmur radiating to axilla 1
• Diagnosis: echocardiography shows flail mitral leaflet 1
• Treatment: emergent surgical repair, intra-aortic balloon pump for stabilization 1

Ventricular septal defect (VSD):

• Occurs 3-5 days post-MI, presents with new harsh holosystolic murmur at left sternal border 1
• Clinical presentation: acute heart failure, cardiogenic shock, step-up in oxygen saturation from right atrium to right ventricle 1
• Diagnosis: echocardiography with color Doppler shows interventricular shunt 1
• Treatment: emergent surgical repair, intra-aortic balloon pump, vasopressors 1

Free wall rupture:

• Occurs 3-5 days post-MI, presents with sudden hemodynamic collapse, electromechanical dissociation 1
• Risk factors: first MI, anterior location, elderly, female, hypertension, no prior angina 1
• Clinical presentation: sudden chest pain, hypotension, pulseless electrical activity, cardiac tamponade 1
• Treatment: emergent pericardiocentesis, surgical repair (mortality >90%) 1

Hemodynamic Complications

Cardiogenic shock:

• Occurs in 5-10% of STEMI patients, mortality 40-50% despite revascularization 1
• Definition: systolic BP <90 mmHg for >30 minutes, cardiac index <2.2 L/min/m², pulmonary capillary wedge pressure >15 mmHg 1
• Clinical presentation: hypotension, cool extremities, altered mental status, oliguria, elevated lactate 1, 3
• Treatment: immediate revascularization (PCI or CABG), inotropes (dobutamine), vasopressors (norepinephrine), mechanical circulatory support (intra-aortic balloon pump, Impella, ECMO) 1, 3

Right ventricular infarction:

• Occurs in 30-50% of inferior MI, presents with hypotension, clear lungs, elevated jugular venous pressure 1
• Diagnosis: ST-elevation ≥1 mm in V4R, echocardiography shows RV dysfunction 1
• Treatment: IV fluid resuscitation (avoid diuretics and nitrates), maintain AV synchrony, inotropes if refractory hypotension 1

Ischemic Complications

Recurrent ischemia/reinfarction:

• Occurs in 5-10% of patients within 30 days 1
• Clinical presentation: recurrent chest pain, new ST-segment changes, troponin re-elevation 1
• Causes: stent thrombosis, incomplete revascularization, progression of non-culprit lesions 1
• Treatment: immediate coronary angiography, repeat PCI or CABG 1

Stent thrombosis:

• Acute (<24 hours), subacute (1-30 days), late (>30 days) 1
• Risk factors: premature discontinuation of dual antiplatelet therapy, underexpansion, residual dissection 1
• Clinical presentation: sudden chest pain, ST-elevation, hemodynamic collapse 1
• Treatment: emergent PCI with thrombectomy, glycoprotein IIb/IIIa inhibitor 1

Other Complications

Heart failure:

• Occurs in 20-30% of STEMI patients 1
• Killip Class II-IV associated with increased mortality 1
• Treatment: diuretics (furosemide), ACE inhibitors, beta-blockers, aldosterone antagonists 1

Pericarditis:

• Early pericarditis (1-3 days): transmural inflammation 1
• Dressler syndrome (weeks to months): autoimmune reaction 1
• Clinical presentation: pleuritic chest pain, pericardial friction rub, diffuse ST-elevation 1
• Treatment: aspirin 650 mg every 6 hours, colchicine 0.6 mg twice daily, avoid NSAIDs 1

Left ventricular thrombus:

• Occurs in 5-15% of anterior MI with apical akinesis 1
• Risk factors: large anterior MI, LVEF <40%, apical aneurysm 1
• Diagnosis: echocardiography or cardiac MRI 1
• Treatment: anticoagulation with warfarin (INR 2-3) for 3-6 months 1

Bleeding complications:

• Major bleeding occurs in 5-10% of patients (dual antiplatelet + anticoagulation + PCI access site) 1
• Access site hematoma, retroperitoneal bleeding, gastrointestinal bleeding, intracranial hemorrhage 1
• Treatment: hold antiplatelet/anticoagulation, transfusion if hemoglobin <7-8 g/dL, surgical intervention if life-threatening 1

Relevant Red Flags & CVICU Tips

Critical red flags requiring immediate physician notification include recurrent chest pain with ST-changes (suggests reocclusion), new murmur (mechanical complication), hypotension with clear lungs (RV infarction or cardiogenic shock), and sudden hemodynamic collapse (free wall rupture or VT/VF). 1, 3

ECG Red Flags

ST-elevation in aVR + V1 with widespread ST-depression:

• Indicates left main or proximal multivessel disease 3
• Associated with 31% in-hospital mortality, 59% severe coronary disease 3
• Requires immediate catheterization regardless of troponin results 3
• High risk for cardiogenic shock and malignant arrhythmias 3
• Consider early mechanical circulatory support 3

Complete normalization of ST-elevation after nitroglycerin:

• Suggests coronary spasm (Prinzmetal angina) with or without MI 1
• Requires early coronary angiography within 24 hours 1
• If recurrent ST-elevation or chest pain, immediate angiography indicated 1

New ST-elevation or ST-depression post-PCI:

• Suggests stent thrombosis, incomplete revascularization, or new occlusion 1
• Obtain immediate 12-lead ECG and notify physician 1
• Prepare for emergent return to catheterization laboratory 1

Hemodynamic Red Flags

Hypotension with clear lung fields:

• Suggests right ventricular infarction (especially with inferior MI) 1
• Check for elevated JVP, Kussmaul sign (JVP rise with inspiration) 1
• Obtain right-sided ECG (ST-elevation in V4R diagnostic) 1
• Critical pitfall: Avoid nitrates and diuretics (worsen hypotension), give IV fluids instead 1

Hypotension with pulmonary edema:

• Suggests cardiogenic shock or mechanical complication 1, 3
• Assess for new murmur (papillary muscle rupture, VSD) 1
• Obtain emergent echocardiography 1
• Prepare for mechanical circulatory support (IABP, Impella) 1, 3

Sudden hemodynamic collapse with pulseless electrical activity:

• Suggests free wall rupture with cardiac tamponade 1
• Obtain emergent echocardiography (pericardial effusion) 1
• Prepare for emergent pericardiocentesis and surgical consultation 1
• Mortality >90% despite intervention 1

Clinical Red Flags

New holosystolic murmur:

• Papillary muscle rupture: murmur radiating to axilla, acute pulmonary edema 1
• Ventricular septal defect: murmur at left sternal border, biventricular failure 1
• Obtain emergent echocardiography and surgical consultation 1
• Prepare for intra-aortic balloon pump and emergent surgery 1

Recurrent chest pain unrelieved by nitroglycerin:

• Suggests stent thrombosis, reocclusion, or incomplete revascularization 1
• Obtain immediate 12-lead ECG 1
• Check troponin (re-elevation confirms reinfarction) 1
• Notify physician for emergent angiography 1

Expanding groin hematoma or thigh swelling:

• Suggests retroperitoneal bleeding (femoral access complication) 1
• Measure thigh circumference serially 1
• Check hemoglobin, type and cross 1
• Prepare for transfusion, vascular surgery consultation if hemodynamically unstable 1

CVICU Tips

Dual antiplatelet therapy adherence:

• Most critical intervention to prevent stent thrombosis 1
• Verify aspirin + P2Y12 inhibitor given and documented 1
• Educate patient on importance of never stopping without cardiology consultation 1
• Prasugrel/ticagrelor preferred over clopidogrel (faster onset, greater platelet inhibition) 1, 3

Beta-blocker timing:

• Initiate within 24 hours if hemodynamically stable 1
• Avoid in acute setting if: heart rate <60 bpm, systolic BP <100 mmHg, signs of heart failure, PR interval >0.24 seconds, second/third-degree AV block 1
• Start low dose (metoprolol 25 mg PO twice daily), titrate gradually 1

Oxygen therapy:

• Only administer if SaO2 <90% or respiratory distress 1
• Routine oxygen in normoxemic patients provides no benefit and may increase mortality 1
• Wean oxygen as soon as SaO2 >90% on room air 1

Morphine use:

• Use cautiously for chest pain unrelieved by nitroglycerin 1
• May delay absorption of oral P2Y12 inhibitors (prasugrel, ticagrelor) 1
• Some studies suggest increased mortality with morphine use 1
• Consider IV nitroglycerin as alternative for pain control 1

Right ventricular infarction management:

• Critical pitfall: Avoid nitrates, diuretics, morphine (all reduce preload and worsen hypotension) 1
• Give IV fluid boluses (500-1000 mL normal saline) to maintain RV preload 1
• Maintain AV synchrony (atrial kick critical for RV filling) 1
• If refractory hypotension, start inotropes (dobutamine) rather than vasopressors 1

Stent thrombosis prevention:

• Ensure dual antiplatelet therapy given before leaving catheterization laboratory 1
• Verify adequate stent expansion and apposition on final angiography 1
• Educate patient on absolute importance of medication adherence 1
• Never stop dual antiplatelet therapy without cardiology consultation 1

Cardiogenic shock management:

• Immediate revascularization (PCI or CABG) is priority 1
• Inotropes (dobutamine 2.5-20 mcg/kg/min) for low cardiac output 1
• Vasopressors (norepinephrine 0.1-0.5 mcg/kg/min) for hypotension despite inotropes 1
• Mechanical circulatory support (IABP, Impella, ECMO) if refractory to medical therapy 1, 3
• Avoid excessive fluid resuscitation (worsens pulmonary edema) 1

Expected Course and Prognostic Clues

Most high lateral STEMI patients stabilize within 24-48 hours post-PCI with gradual improvement in symptoms, allowing discharge at 48-72 hours if uncomplicated, though long-term prognosis depends on LVEF, completeness of revascularization, and adherence to secondary prevention. 1

Acute Phase (0-48 hours)

Immediate post-PCI period:

• Chest pain resolves within 1-2 hours post-successful reperfusion 1
• ST-segments normalize or significantly improve within 60-90 minutes (>50% resolution indicates successful reperfusion) 1
• Troponin peaks at 12-24 hours, then gradually declines over 7-14 days 1
• Highest risk for ventricular arrhythmias (VT/VF) in first 48 hours 1
• Hemodynamic stabilization expected within 24 hours if no complications 1

Prognostic indicators:

• TIMI flow grade 3 (normal flow) post-PCI associated with lowest mortality 2
• ST-segment resolution >50% at 60-90 minutes predicts smaller infarct size and better outcomes 1
• Peak troponin level correlates with infarct size and mortality 1
• Killip class at presentation: Class I (6% mortality), Class II (17%), Class III (38%), Class IV (81%) 1

Subacute Phase (48 hours - 7 days)

Clinical course:

• Transition from IV to oral medications 1
• Mobilization and cardiac rehabilitation initiation 1
• Echocardiography to assess LVEF and wall motion abnormalities 1
• Risk stratification for ICD (if LVEF ≤35%) and cardiac rehabilitation 1
• Early discharge at 48-72 hours if uncomplicated (no recurrent ischemia, arrhythmias, heart failure, mechanical complications) 1

Complications peak:

• Mechanical complications (papillary muscle rupture, VSD, free wall rupture) occur 2-7 days post-MI 1
• Early pericarditis (1-3 days) presents with pleuritic chest pain, friction rub 1
• Stent thrombosis risk highest in first 30 days (subacute stent thrombosis) 1

Long-term Course (>7 days)

Cardiac rehabilitation:

• Initiate within 1-2 weeks post-discharge 1
• Improves functional capacity, reduces mortality, enhances quality of life 1
• Includes exercise training, risk factor modification, psychosocial support 1

Secondary prevention:

• Dual antiplatelet therapy for 12 months 1
• Aspirin indefinitely 1
• High-intensity statin indefinitely (target LDL <70 mg/dL) 1
• Beta-blocker indefinitely (especially if LVEF ≤40%) 1
• ACE inhibitor/ARB indefinitely (especially if LVEF ≤40%, heart failure, diabetes, hypertension) 1
• Aldosterone antagonist if LVEF ≤40% and heart failure or diabetes 1

Follow-up:

• Cardiology follow-up at 2-6 weeks post-discharge 1
• Repeat echocardiography at 6-12 weeks to reassess LVEF for ICD consideration 1
• Stress testing at 3-6 weeks if incomplete revascularization or recurrent symptoms 1
• Annual cardiology follow-up indefinitely 1

Prognostic Factors

Favorable prognosis:

• TIMI flow grade 3 post-PCI 2
• ST-segment resolution >50% at 60-90 minutes 1
• LVEF >40% 1
• Killip class I (no heart failure) 1
• Complete revascularization 1
• Small infarct size (low peak troponin) 1
• No mechanical complications 1
• Adherence to guideline-directed medical therapy 1

Unfavorable prognosis:

• Cardiogenic shock (40-50% mortality despite revascularization) 1
• LVEF ≤35% (increased risk of sudden cardiac death, heart failure) 1
• Mechanical complications (papillary muscle rupture, VSD, free wall rupture) 1
• Incomplete revascularization 1
• Recurrent ischemia/reinfarction 1
• Diabetes, chronic kidney disease, advanced age 1
• Non-adherence to dual antiplatelet therapy (stent thrombosis risk) 1

Long-term mortality:

• 30-day mortality: 5-10% overall, <5% if uncomplicated, >50% if cardiogenic shock 1
• 1-year mortality: 10-15% overall, varies by LVEF and comorbidities 1
• 5-year mortality: 20-30%, primarily driven by LVEF, heart failure, recurrent events 1
• Most deaths occur in first 48 hours (ventricular arrhythmias, cardiogenic shock) 1