What are the criteria for diagnosing cardiogenic shock?

Diagnostic Criteria for Cardiogenic Shock

Cardiogenic shock requires BOTH sustained hypotension (systolic BP <90 mmHg for >30 minutes OR mean arterial pressure <60 mmHg OR need for vasopressors to maintain these thresholds) AND clinical evidence of end-organ hypoperfusion—hypotension alone is insufficient for diagnosis. 1

Clinical Diagnostic Criteria

The diagnosis mandates meeting both components simultaneously 1:

Hypotension Component (must meet ≥1):

• Systolic BP <90 mmHg sustained for >30 minutes 1
• Mean arterial pressure <60 mmHg for >30 minutes 1
• Requirement of vasopressors to maintain systolic BP ≥90 mmHg or MAP ≥60 mmHg 1

End-Organ Hypoperfusion (must have ≥1 sign):

• Decreased mentation/altered mental status 1
• Cold extremities with livedo reticularis 1
• Urine output <30 mL/hour 1
• Lactate >2 mmol/L 1
• Metabolic acidosis 1
• Mixed venous oxygen saturation (SvO₂) <65% 1

Hemodynamic Diagnostic Criteria

When invasive monitoring is available, cardiogenic shock diagnosis requires ALL three core parameters plus systolic BP <90 mmHg 1:

Core Hemodynamic Parameters:

• Cardiac index <2.2 L/min/m² (some sources use <2.0 L/min/m²) 1
• Pulmonary capillary wedge pressure (PCWP) >15 mmHg 1
• Systolic BP <90 mmHg or mean BP <60 mmHg 1

Additional Hemodynamic Markers (supportive but not required):

• Cardiac power output <0.6 W (calculated as [CO × MAP]/451) 1
• Shock index >1.0 (heart rate/systolic BP) 1
• Central venous pressure >15 mmHg 1, 2

Right Ventricular Shock-Specific Criteria:

• Pulmonary artery pulsatility index [(PASP-PADP)/CVP] <1.0 1
• CVP >15 mmHg 1
• CVP-PCWP ratio >0.6 1

SCAI Staging Classification

The Society for Cardiovascular Angiography and Interventions provides a five-stage system for risk stratification 1, 2:

Stage A (At Risk):

• Normal hemodynamics, normotensive (SBP >100 mmHg), normal perfusion, warm extremities 1
• Normal renal function and lactate 1

Stage B (Beginning Shock/"Pre-shock"):

• Elevated venous pressure, hypotension (SBP <90 mmHg, MAP <60 mmHg, or >30 mmHg drop from baseline) 1
• Normal perfusion still present with warm extremities 1
• Heart rate >100 bpm, cardiac index ≤2.2 L/min/m² 1
• Preserved renal function, normal lactate, elevated BNP 1

Stage C (Classic Cardiogenic Shock):

• Elevated venous pressure, hypotension, hypoperfusion present 1
• Cold/ashen extremities with livedo, weak or nonpalpable pulses, altered mentation 1
• Decreased urine output, respiratory distress 1
• Impaired renal function, increased lactate and liver function tests 1
• Cardiac index ≤2.2 L/min/m², PCWP >15 mmHg, cardiac power output <0.6 W 1

Stage D (Deteriorating):

• Same as Stage C but worsening despite escalating vasopressors or mechanical circulatory support 1
• Persistent or worsening laboratory values 1

Stage E (Extremis):

• Cardiac arrest, refractory hypotension/hypoperfusion requiring CPR 1
• Pulseless electrical activity (PEA), recurrent ventricular tachycardia/fibrillation 1
• SBP only maintained with resuscitation 1

Critical Diagnostic Pitfalls

Common Mistake: Diagnosing shock based on hypotension alone

• Hypotension is the primary clinical manifestation but insufficient for diagnosis without evidence of end-organ hypoperfusion 1
• Always assess for clinical signs: mental status changes, cold extremities, oliguria, elevated lactate 1

Distinguishing from other shock types:

• Cardiogenic shock: Elevated PCWP (>15 mmHg), elevated CVP, elevated systemic vascular resistance 1, 2
• Hypovolemic shock: Low PCWP (<15 mmHg), low CVP, cold extremities but responds to fluid challenge 3
• Distributive shock: Low systemic vascular resistance, normal or increased cardiac output initially, warm extremities 2

Hemodynamic monitoring considerations:

• The 2022 ACC/AHA guidelines note there is no agreement on optimal hemodynamic monitoring method, including use of pulmonary artery catheters 1
• Arterial line monitoring is recommended for continuous blood pressure assessment 1
• Dynamic changes occur rapidly—continuous reassessment is essential 2

Fluid challenge before diagnosis:

• A fluid challenge (>200 mL saline or Ringer's lactate over 15-30 minutes) should be attempted first if no overt fluid overload is present 1
• This helps distinguish cardiogenic from hypovolemic shock 1

Immediate Assessment Requirements

When cardiogenic shock is suspected 1:

• ECG immediately to identify acute coronary syndrome 1
• Echocardiography immediately to assess cardiac function and identify mechanical complications 1
• Invasive arterial monitoring for continuous blood pressure assessment 1
• Transfer to tertiary care center with 24/7 cardiac catheterization and mechanical circulatory support capabilities 1