What is the role of thrombolytic therapy, such as alteplase (tissue plasminogen activator), in cardiac arrest due to cardiac etiologies or presumed pulmonary embolism?

Thrombolytic Therapy in Cardiac Arrest Due to Cardiac Etiologies or Pulmonary Embolism

Thrombolytic therapy is strongly recommended for cardiac arrest due to confirmed pulmonary embolism (PE) and should be considered when PE is strongly suspected as the cause of arrest, with alteplase 50 mg IV bolus (with option to repeat in 15 minutes) being the preferred regimen. 1

Presentation and Diagnosis of PE-Related Cardiac Arrest

• Pulseless electrical activity (PEA) is the most common presenting rhythm in PE-related cardiac arrest (36-53% of cases) 2, 1
• PE accounts for 5-13% of unexplained cardiac arrests 1
• Warning signs before arrest may include:
  • Dyspnea or respiratory distress
  • Chest pain
  • Syncope or pre-syncope
  • Hemoptysis 1
• Risk factors include:
  • Recent immobilization or surgery
  • Lower limb trauma/surgery
  • History of DVT or PE
  • Pregnancy or postpartum state 1
  • Note: 40% of PE patients have no identifiable risk factors 1

Thrombolytic Therapy Recommendations

For Confirmed PE:

• Thrombolysis is a reasonable emergency treatment option (Class IIa, LOE C-LD) 2
• Options include:
  • Alteplase 50 mg IV bolus with option to repeat in 15 minutes 2, 1
  • Single-dose weight-based tenecteplase 2, 1
• Thrombolysis remains beneficial even when chest compressions have been provided 2

For Suspected PE:

• Thrombolysis may be considered when cardiac arrest is suspected to be caused by PE (Class IIb, LOE C-LD) 2
• Standard contraindications to thrombolysis may be superseded by the need for potentially lifesaving intervention 2

Efficacy and Outcomes

• Early administration of systemic thrombolysis is associated with improved resuscitation outcomes compared to use after failure of conventional ACLS 2
• Thrombolytic therapy is associated with higher rates of return of spontaneous circulation (ROSC) (OR 2.55,95% CI = 1.50-4.34) 3
• However, studies have not shown a significant difference in survival to hospital discharge (OR 1.41,95% CI = 0.79-2.41) 3
• Mortality remains extremely high (65-90%) in PE-related cardiac arrest 1

Dosing Strategies

• The most common effective dosing strategy is a single 50-mg bolus of alteplase 4
• Bolus-only administration allows for shorter time from cardiac arrest onset to alteplase administration (mean 15.1 minutes) compared to infusion-only (46.4 minutes) or bolus-with-infusion (48.0 minutes) 4
• Higher cumulative alteplase doses have been associated with increased ROSC 4
• Alteplase has a short initial half-life of less than 5 minutes, allowing for rapid action 5

Bleeding Risk Considerations

• Despite concerns, thrombolysis during CPR has shown fewer bleeding complications than anticipated 6
• Studies have not shown a significant difference in bleeding complications with thrombolysis during cardiac arrest (OR 2.21,0.95-5.17) 3
• The risk of bleeding should not prevent treatment given the high mortality without intervention 1

Alternative Interventions

• Surgical or percutaneous mechanical embolectomy are reasonable alternatives for confirmed PE-related arrest 2
• However, surgical embolectomy should be avoided in patients who have received CPR 2
• ECPR may be considered for refractory arrest 2, 1

Post-Arrest Management

• Initiate anticoagulation typically 3 hours after thrombolysis 1
• Implement standard post-cardiac arrest care, including consideration of therapeutic hypothermia if patient remains comatose 1
• Treat hypoxemia and hypotension aggressively 1

Important Caveats

• The evidence regarding treatment strategies for PE-related cardiac arrest is largely observational 2
• Diagnostic confirmation should not delay treatment in highly suspicious cases 1
• Thrombolytics are administered with or followed by systemic anticoagulation 2, 1
• Coagulation tests may be unreliable during alteplase therapy 7