What is the treatment for myocarditis with severe refractory shock?

Treatment of Myocarditis with Severe Refractory Shock

For patients with myocarditis and severe refractory shock, venoarterial extracorporeal membrane oxygenation (VA-ECMO) should be implemented immediately as the primary rescue therapy, along with appropriate pharmacological support and consideration of other mechanical circulatory support devices.

Initial Pharmacological Management

First-line Vasopressors and Inotropes

1. Norepinephrine as the initial vasopressor after adequate fluid resuscitation 1

   • Start at low dose and titrate to maintain MAP ≥65 mmHg
   • Preferred over dopamine due to fewer tachyarrhythmias

2. Add vasopressin (up to 0.03 U/min) if hypotension persists despite norepinephrine 1, 2

   • Helps reduce norepinephrine requirements
   • May reduce renal replacement therapy needs
   • Dosing:
     • Post-cardiotomy shock: 0.03 to 0.1 units/minute
     • Septic shock: 0.01 to 0.07 units/minute

3. Inotropic support for myocardial depression 1

   • Dobutamine added to norepinephrine regimen
   • Epinephrine as a single agent alternative
   • Milrinone may be considered for patients with elevated systemic vascular resistance

Corticosteroid Therapy

• IV corticosteroids should be considered for suspected or confirmed myocarditis with hemodynamic compromise 1
• Particularly beneficial in COVID-19 related myocarditis with inflammatory markers
• For fulminant myocarditis with severe inflammatory infiltrates on biopsy

Mechanical Circulatory Support

Indications for Advanced Support

When pharmacological therapy fails to stabilize the patient:

1. Intra-aortic balloon pump (IABP) 1

   • Class IIa recommendation for cardiogenic shock after myocardial infarction
   • Bridge to more advanced support if needed

2. VA-ECMO 1, 3, 4

   • Indicated for refractory shock despite optimal medical therapy
   • Should be initiated early in fulminant myocarditis with cardiogenic shock
   • Provides biventricular support and cardiac decompression
   • Technical considerations:
     • Flows >110 mL/kg/min should be avoided to prevent hemolysis 1
     • Monitor free hemoglobin (maintain <10 μg/dL)
     • Normalize calcium in RBC pump prime (300 mg CaCl₂ per unit)

3. Other ventricular assist devices 1, 5, 6

   • Consider CentriMag or other temporary devices if VA-ECMO is insufficient
   • May be used as a bridge to recovery or transplantation

Special Considerations

Specific Etiologies

• Viral myocarditis: Support with mechanical devices while awaiting recovery 5, 4
• COVID-19 myocarditis: Consider additional anti-inflammatory therapy 1
• Immune checkpoint inhibitor myocarditis: May require immunosuppression with glucocorticoids, IVIG, or plasma exchange 1

Additional Therapies

• High-dose insulin therapy (up to 10 U/kg/hr) for refractory shock 1

  • Start at 1 U/kg bolus with 0.5 g/kg dextrose
  • Continue infusion at 0.5-1 U/kg/hr
  • Monitor glucose every 15-30 minutes initially
  • Target glucose 100-250 mg/dL
  • Maintain potassium at 2.5-2.8 mEq/L (avoid aggressive repletion)

• IV calcium for refractory shock 1

  • 0.3 mEq/kg calcium (0.6 mL/kg of 10% calcium gluconate)
  • Follow with infusion of 0.3 mEq/kg/hr
  • Monitor ionized calcium levels

• Lipid emulsion therapy for refractory shock 1

  • Consider in periarrest situations
  • 1.5 mL/kg of 20% lipid emulsion as bolus
  • May repeat up to twice as needed
  • Follow with infusion of 0.25 mL/kg/min for 30-60 minutes
  • Maximum 24-hour dose: 12.5 mL/kg

Monitoring and Follow-up

• Cardiac MRI should be performed once patient is stabilized to confirm diagnosis and assess extent of inflammation 1
• Initiate guideline-directed heart failure therapy before discharge
• Avoid strenuous physical activity for 3-6 months
• Schedule follow-up testing (ECG, echocardiogram, ambulatory rhythm monitor, CMR) at 3-6 months

Pitfalls to Avoid

1. Delayed recognition of myocarditis as cause of shock
2. Inadequate monitoring of glucose and electrolytes during high-dose insulin therapy
3. Excessive fluid resuscitation in patients with myocarditis
4. Delayed initiation of mechanical support in deteriorating patients
5. Failure to consider immunosuppressive therapy in appropriate cases

The mortality rate for fulminant myocarditis with cardiogenic shock remains high, but early implementation of mechanical circulatory support can rescue up to 68% of patients 7. Prompt recognition and aggressive intervention are essential for improving outcomes.