2.3 Acute Reperfusion Strategies & Nursing Management

Primary PCI vs. Fibrinolytic Decision Pathways

In acute STEMI, "time is muscle." Myocardial necrosis begins within 20 minutes of complete coronary occlusion and reaches maximum transmural extent within 6 hours. Emergency reperfusion therapy is mandatory for all patients presenting within 12 hours of symptom onset with clinical STEMI.

Reperfusion Strategy Timelines & Benchmarks

1. Primary Percutaneous Coronary Intervention (PCI): Primary PCI (balloon angioplasty, aspiration thrombectomy, and stenting) is the preferred reperfusion modality. It achieves superior vessel patency (TIMI 3 flow in >90% of cases), lower rates of re-infarction, and avoids intracranial hemorrhage risks compared to fibrinolysis.
   • PCI-Capable Facility: First Medical Contact (FMC) to PCI device time must be ≤ 90 minutes.
   • Non-PCI Facility (Transfer): If a patient presents to a non-PCI facility, emergency transfer to a PCI center is required if FMC-to-device time can be achieved within ≤ 120 minutes. If the expected delay exceeds 120 minutes, immediate fibrinolytic therapy must be administered.
2. Fibrinolytic Therapy: Indicated for STEMI presenting within 12 hours of symptom onset when primary PCI cannot be delivered within 120 minutes of FMC.
   • Door-to-Needle Benchmark: Fibrinolytic administration must occur within ≤ 30 minutes of emergency department arrival.
   • Agents: Fibrin-specific agents are preferred: Tenecteplase (TNK-tPA, administered as a single IV weight-based bolus over 5 seconds), Reteplase (rPA), or Alteplase (tPA).
   • Pharmacoinvasive Strategy: Following fibrinolysis, all patients should be transferred to a PCI center. If fibrinolysis fails (indicated by <50% resolution of ST elevation at 60-90 minutes post-bolus), emergency rescue PCI is performed immediately. If fibrinolysis is successful, routine angiography is performed within 2 to 24 hours.

STEMI Patient Presentation (Symptoms <12 hours)
  │
  ├──> Primary PCI Available within 120 min FMC?
  │     ├──> YES: Primary PCI (Target FMC-to-Device <90 min if direct, <120 min if transfer)
  │     └──> NO:  Fibrinolytic Therapy (Target Door-to-Needle <30 min)
  │                 │
  │                 ├──> Assess ST Resolution at 60-90 min
  │                 │     ├──> Failed (<50% resolution): Rescue PCI Immediately
  │                 │     └──> Successful (≥50% resolution): Routine Angiography in 2-24 hours

Absolute Contraindications to Fibrinolytic Therapy

Nurses must immediately screen STEMI candidates for absolute contraindications before administering fibrinolytic agents:

• Any prior history of intracranial hemorrhage (ICH).
• Known structural cerebrovascular lesion (e.g., arteriovenous malformation).
• Known malignant intracranial neoplasm (primary or metastatic).
• Ischemic stroke within the preceding 3 months (excluding acute ischemic stroke within 4.5 hours).
• Suspected aortic dissection.
• Active bleeding or bleeding diathesis (excluding menses).
• Significant closed-head or facial trauma within the preceding 3 months.
• Intracranial or intraspinal surgery within 2 months.
• Severe uncontrolled hypertension unresponsive to emergency therapy (systolic BP >180 mmHg or diastolic BP >110 mmHg).

Antithrombotic & Antiplatelet Pharmacotherapy

Secondary prevention of stent thrombosis and propagation of coronary thrombi requires potent combination antithrombotic therapy.

Dual Antiplatelet Therapy (DAPT)

DAPT combines Aspirin with an oral P2Y₁₂ receptor inhibitor:

• Aspirin: Loaded immediately with 162 to 325 mg non-enteric coated chewable aspirin, followed by 81 mg daily indefinitely.
• P2Y₁₂ Inhibitors:
  • Ticagrelor (Brilinta): Loaded with 180 mg, followed by 90 mg BID. Direct, reversible P2Y₁₂ inhibitor. Preferred over clopidogrel due to superior mortality reduction.
  • Prasugrel (Effient): Loaded with 60 mg, followed by 10 mg daily. Irreversible P2Y₁₂ inhibitor. Absolute Contraindication: Prior history of stroke or Transient Ischemic Attack (TIA) due to severe risk of intracranial bleeding.
  • Clopidogrel (Plavix): Loaded with 300 to 600 mg, followed by 75 mg daily. Prodrug requiring hepatic CYP2C19 cleavage. Reserved for cases where ticagrelor/prasugrel are unavailable or contraindicated.

Parenteral Anticoagulation

Parenteral anticoagulants are administered during PCI and maintained in NSTEMI/UA:

• Unfractionated Heparin (UFH): IV bolus (70-100 units/kg) to maintain target Activated Clotting Time (ACT) 250-300 seconds during PCI (or aPTT 50-70 seconds post-PCI).
• Bivalirudin (Angiomax): Direct thrombin inhibitor. Associated with significantly lower rates of major bleeding compared to heparin plus GP IIb/IIIa inhibitors in high-bleeding-risk PCI.
• Enoxaparin (LMWH): Preferred parenteral anticoagulant in NSTEMI managed medically.

Glycoprotein IIb/IIIa Inhibitors

Agents such as Eptifibatide (Integrilin) and Tirofiban (Aggrastat) block the final common pathway of platelet aggregation. They are utilized as bailout therapy in the catheterization laboratory during PCI for heavy intra-coronary thrombus burden, no-reflow phenomenon, or acute intra-procedural thrombotic complications.

Post-PCI Vascular Access Sheath Care & Complication Management

Vascular access for PCI is achieved via the radial or femoral artery. Nurses manage post-procedural hemostasis and rapidly identify access site complications.

Femoral Access Sheath Removal & Care

• Pre-removal Checks: Verify coagulation parameters: Activated Clotting Time (ACT) must be <150-180 seconds (or aPTT <45 seconds) prior to manual sheath pull.
• Manual Pull Technique: Apply direct manual compression 1 to 2 cm proximal to the skin puncture site (the arteriotomy site is located superior to the skin nick) for 20 to 30 minutes. Maintain bed rest flat (head of bed ≤ 30^°) with the affected leg immobilized for 4 to 6 hours.
• Vascular Closure Devices (VCDs): Devices like Angio-Seal (collagen plug) or Perclose (suture-mediated) reduce bed rest times to 2 hours.

Radial Access & Compression Devices

Radial artery access is now preferred due to dramatically lower vascular bleeding complications. A radial compression device (TR Band) is applied. Air is sequentially deflated per protocol over 2 to 4 hours while assessing for radial artery patency (using the Barbeau test) and absence of hematoma.

Major Access Site Complications

1. Retroperitoneal Hematoma (RPH): A rare but life-threatening complication resulting from a high femoral arterial puncture (above the inferior epigastric artery or inguinal ligament), allowing uncontained bleeding into the retroperitoneal space.
   • Clinical Presentation: Unexplained sudden back pain, flank pain, ipsilateral groin pain, combined with sudden refractory hypotension, tachycardia, and a dropping hemoglobin/hematocrit.
   • Diagnostic Choice: Non-contrast CT scan of the abdomen and pelvis.
   • Nursing Interventions: Immediately apply firm manual pressure over the femoral site, administer rapid IV fluid boluses and blood products, reverse active anticoagulation (protamine for heparin), and notify vascular surgery.
2. Pseudoaneurysm: Disruption of arterial wall layers resulting in a pulsating hematoma encapsulated by fibrous tissue, maintaining communication with the arterial lumen.
   • Presentation: A painful, pulsatile mass at the groin access site with an audible bruit on auscultation.
   • Confirmation & Management: Confirmed via duplex ultrasound. Small pseudoaneurysms (<2 cm) are monitored; larger ones are treated with ultrasound-guided thrombin injection or surgical repair.
3. Contrast-Induced Acute Kidney Injury (CI-AKI): An absolute rise in serum creatinine ≥ 0.5 mg/dL or ≥ 25% baseline increase within 48 to 72 hours post-contrast administration.
   • Prevention Protocol: Aggressive isotonic IV normal saline hydration (1.0-1.5 mL/kg/h for 12 hours pre- and post-PCI), minimization of contrast volume, and holding nephrotoxic medications (NSAIDs, ACE inhibitors, ARBs).