What is the management of cardiogenic shock?

Management of Cardiogenic Shock

Immediate Diagnosis and Assessment

Diagnose cardiogenic shock based on systolic blood pressure <90 mmHg for 30 minutes (or requiring vasopressors/inotropes to maintain SBP >90 mmHg), combined with evidence of end-organ hypoperfusion including elevated lactate >2 mmol/L, decreased urine output <0.5 mL/kg/h, altered mental status, and cool extremities. 1, 2

Hemodynamic Criteria

• Cardiac index <1.8 L/min/m² without support or <2.2 L/min/m² with support 1, 2
• Cardiac power output <0.6 W (most critical threshold for refractory shock) 1
• Pulmonary capillary wedge pressure >15-20 mmHg (indicates left ventricular failure) 1, 2
• Central venous pressure >15 mmHg (suggests right ventricular involvement or biventricular failure) 1

Essential Diagnostic Studies

• Immediate ECG and Doppler echocardiography to assess ventricular function, valvular abnormalities, and detect mechanical complications 1, 2
• Early invasive hemodynamic assessment with pulmonary artery catheter to identify specific shock phenotype and guide therapy 1, 2
• Arterial line placement for continuous accurate blood pressure monitoring 2
• Laboratory evaluation: cardiac biomarkers, lactate levels, and organ function tests 2

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Algorithmic Management Approach

Step 1: Revascularization (For AMI-Related Cardiogenic Shock)

Perform immediate coronary angiography within 2 hours with intent to revascularize - this is the single most important intervention for AMI-related cardiogenic shock. 1, 2

• If coronary anatomy is suitable: proceed with immediate PCI 2
• If PCI unsuitable or failed: emergency CABG is recommended 2
• If PCI would be delayed >120 minutes in STEMI: consider immediate fibrinolysis and transfer to PCI center 2
• Complete revascularization during index procedure should be considered 2

Step 2: Hemodynamic Support

Initial Fluid Assessment

Perform fluid challenge (saline or Ringer's lactate >200 mL over 15-30 minutes) as first-line treatment ONLY if there are no signs of overt fluid overload. 1 This applies to patients with hypotension and normal perfusion without congestion after ruling out mechanical complications. 2

Critical pitfall: In right ventricular infarction, avoid volume overload as it worsens hemodynamics. 2

Vasopressor Therapy

Norepinephrine is the preferred first-line vasopressor when mean arterial pressure needs pharmacologic support. 1, 2 This represents a consensus across both American and European guidelines.

Inotropic Therapy

Dobutamine (2-20 μg/kg/min) is the first-line inotropic agent to increase cardiac output when signs of low cardiac output persist despite adequate blood pressure. 1, 2

• For patients with heart failure and pulmonary congestion but adequate blood pressure (SBP >90 mmHg), consider dobutamine or levosimendan 2
• Levosimendan may be a useful addition to medical therapy in cardiogenic shock 3

Step 3: Respiratory Support

Provide oxygen and mechanical respiratory support according to blood gases. 2

• Non-invasive positive pressure ventilation for patients with pulmonary edema and respiratory distress (respiratory rate >25 breaths/min, SaO2 <90%) 2
• Endotracheal intubation and mechanical ventilation for patients unable to achieve adequate oxygenation 2

Step 4: Mechanical Circulatory Support (MCS)

Consider short-term MCS in refractory cardiogenic shock based on patient age, comorbidities, and neurological function. 1, 2

Defining Refractory Shock

Refractory shock is characterized by:

• Cardiac power output <0.6 W (most critical threshold) 1
• Persistent tissue hypoperfusion despite adequate doses of two vasoactive medications 1
• Progressive deterioration requiring increasing inotrope doses 1

MCS Device Selection Based on Phenotype

Left Ventricular-Dominant Shock (CPO <0.6 W, PCWP >15 mmHg, RA <15 mmHg):

• Consider percutaneous ventricular assist devices 1

Right Ventricular-Dominant Shock (CPO <0.6 W, RA >15 mmHg, PCWP <15 mmHg):

• Requires RV-specific support strategies 1

Biventricular Shock (CPO <0.6 W, both RA >15 mmHg and PCWP >15 mmHg):

• May require ECMO or biventricular support 1

Critical Evidence on IABP

Routine use of intra-aortic balloon pump (IABP) in cardiogenic shock is NOT recommended as randomized trials have not shown mortality benefit. 1, 2 However, IABP should be considered specifically for hemodynamic instability due to mechanical complications (e.g., ventricular septal rupture, acute mitral regurgitation). 2

Important caveat: Despite lack of mortality benefit in routine use, evidence for improved survival from randomized studies on IABP combined with PCI is lacking, yet many hospitals still use IABP for initial stabilization. 3

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Special Considerations

Valvular Disease

Emergency cardiac surgery is the gold standard treatment for cardiogenic shock due to valvular disease. 1 Mechanical complications should be treated as early as possible after Heart Team discussion. 2

Monitoring Targets

• Wedge pressure <20 mmHg 2
• Cardiac index >2 L/min/m² 2
• Mean arterial pressure adequate to maintain perfusion 1, 2
• Lactate normalization 2

Contraindications to MCS Escalation

• Anoxic brain injury 1
• Irreversible end-organ failure 1
• Prohibitive vascular access 1
• Do Not Resuscitate status 1

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System-Based Approach

Transfer patients with cardiogenic shock to a tertiary care center with 24/7 cardiac catheterization capability and mechanical circulatory support availability. 1, 2

Implement a multidisciplinary shock team approach for complex cases - this team-based management has been associated with improved 30-day all-cause mortality. 1, 2 The shock team provides opportunity for various clinicians (interventional cardiologists, cardiac surgeons, heart failure specialists, intensivists) to contribute perspective on device selection, timing, and exit strategy. 2

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Common Pitfalls to Avoid

• Do not delay diagnosis - cardiogenic shock has approximately 50% in-hospital mortality despite modern treatment 2
• Avoid routine IABP use - no mortality benefit demonstrated 1, 2
• Do not volume overload RV infarction - worsens hemodynamics 2
• Avoid prolonged medical optimization attempts - apply IABP within 30 minutes and consider MCS within 1 hour from first weaning attempts to prevent complications 1
• Do not confuse late-stage septic shock with cardiogenic shock - septic shock maintains decreased SVR as primary pattern despite myocardial depression 1

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Prognostic Considerations

Despite advances in treatment, 30-day mortality remains 40-50% in contemporary studies. 2 Mortality increases stepwise with SCAI shock stage progression (A through E), and presence of cardiac arrest significantly increases mortality at every stage. 1 The economic impact is substantial, with multiorgan system failure associated with nearly 50% in-hospital mortality, longer lengths of stay, and greater resource utilization. 1