Can cardiogenic shock occur with normal blood pressure?

Normotensive Cardiogenic Shock: A Critical Entity in Cardiac Care

Yes, normotensive cardiogenic shock is a recognized clinical entity that can occur despite normal blood pressure and represents a high-risk condition requiring urgent intervention. 1 This condition, sometimes called "pre-shock" or "beginning shock," is characterized by tissue hypoperfusion despite maintained blood pressure, often due to compensatory vasoconstriction.

Definition and Recognition

Cardiogenic shock traditionally includes:

• Hypotension (SBP <90 mmHg for >30 minutes)
• Signs of hypoperfusion (altered mental status, cold extremities, decreased urine output, elevated lactate)
• Cardiac dysfunction (reduced cardiac output/index)

However, the Society for Cardiovascular Angiography and Interventions (SCAI) classification system specifically recognizes normotensive shock as "Stage B: Beginning shock" with these characteristics 1, 2:

• Normal to near-normal blood pressure
• Evidence of hypoperfusion
• Preserved mental status
• Elevated venous pressure
• Strong pulses
• Warm extremities

Pathophysiology and Significance

Normotensive cardiogenic shock occurs when:

• Compensatory vasoconstriction maintains blood pressure despite reduced cardiac output
• The body sacrifices peripheral perfusion to maintain central perfusion
• Systemic vascular resistance increases significantly to compensate for decreased cardiac output

This condition is particularly dangerous because:

• It can falsely reassure clinicians due to normal blood pressure readings 1
• It represents 5.2% of cardiogenic shock cases in the SHOCK trial registry 1
• These patients had lower average cardiac output compared to hypotensive shock patients 1
• In-hospital mortality is 43% - significantly higher than patients without shock but lower than classic hypotensive shock (66%) 3

Diagnostic Approach

To identify normotensive cardiogenic shock:

1. Clinical assessment:

   • Look for signs of hypoperfusion despite normal BP
   • Cold extremities with livedo reticularis
   • Decreased urine output (<30 mL/h)
   • Altered mental status (may be subtle)
   • Elevated jugular venous pressure

2. Laboratory evaluation:

   • Lactate >2 mmol/L
   • Elevated BNP
   • Preserved renal function initially
   • Metabolic acidosis

3. Hemodynamic parameters (if available):

   • Cardiac index <2.2 L/min/m²
   • Pulmonary capillary wedge pressure >15 mmHg
   • Heart rate >100 bpm
   • Shock index (HR/SBP) >1.0 1

Management Considerations

Early recognition and intervention are critical:

1. Immediate assessment:

   • ECG and echocardiography are required immediately 1
   • Invasive hemodynamic monitoring with arterial line 1
   • Consider pulmonary artery catheter for accurate hemodynamic assessment 1, 2

2. Initial management:

   • Fluid challenge (>200 mL/15-30 min) if no overt fluid overload 1
   • Inotropic support with dobutamine to increase cardiac output 1
   • Consider levosimendan, especially in patients on beta-blockers 1, 4
   • Avoid vasopressors initially unless strictly necessary to maintain perfusion 1

3. Definitive care:

   • Rapid transfer to a tertiary care center with 24/7 cardiac catheterization and ICU capabilities 1
   • Early coronary revascularization if ischemia is the underlying cause 2
   • Consider mechanical circulatory support in refractory cases 1, 2

Clinical Pearls and Pitfalls

• Major pitfall: Failing to recognize shock due to normal blood pressure readings
• Pearl: Shock index (HR/SBP) >1.0 can help identify patients at risk despite normal BP 1
• Pearl: Target MAP ≥70 mmHg once shock is recognized, as lower MAP is associated with worse outcomes 5
• Pitfall: Delaying definitive treatment due to apparent hemodynamic stability
• Pearl: Early invasive hemodynamic assessment can identify shock phenotype (LV, RV, or biventricular) 1, 2

Normotensive cardiogenic shock represents an important diagnostic and therapeutic challenge that requires vigilance, early recognition, and prompt intervention to improve outcomes in this high-risk patient population.