Cardiogenic Shock 

Definition

Cardiogenic shock (CS) is a state of critical end-organ hypoperfusion due to primary cardiac pump failure, despite adequate intravascular volume, leading to:

  • Low cardiac output(Cardiac index<2.2 L/min/m²)
  • Elevated filling pressures(elevated pulmonary-capillary wedge pressure >15 mm Hg.)
  • SBP <90 mmHg or MAP <65 mmHg for >30 min
  • OR need for vasopressors/inotropes to maintain BP
  • Plus signs of hypoperfusion (Urine output less than or equal to  30 mL/hr ), altered mentation, cold clammy skin, ↑ lactate)

Etiology 

1. Ischemic

  • Acute myocardial infarction most common cause (>70%)(LAD > RCA > LCX)

2. Non-Ischemic

  • Acute decompensated heart failure
  • Severe cardiomyopathy (DCM, HCM)
  • Myocarditis
  • Takotsubo cardiomyopathy

3. Arrhythmia-Related

  • Sustained VT/VF
  • Complete heart block
  • Rapid AF with poor LV function

4. Valvular

  • Acute severe MR
  • Acute severe AR
  • Critical AS

5. Right Ventricular Failure

  • RV infarction
  • Massive PE (overlaps with obstructive shock)
  • Pulmonary hypertension crisis

Pathophysiology

Core Hemodynamic Problem-derangement to both systolic and diastolic left ventricular function, 

↓ Myocardial contractility → ↓ Stroke volume → ↓ Cardiac output → ↓ MAP → tissue hypoxia

Maladaptive Responses

  • Sympathetic activation → ↑ SVR → ↑ afterload → worsens LV failure
  • RAAS activation → Na⁺/water retention → ↑ preload → pulmonary congestion
  • Coronary hypoperfusion → ongoing ischemia → vicious cycle

Microcirculatory Dysfunction

  • Elevated lactate despite “normal” macro-parameters
  • Mitochondrial dysfunction → cytopathic hypoxia


Hemodynamic Profile

Parameter

Cardiogenic Shock

Cardiac Output

↓↓↓

Cardiac Index

<2.2 L/min/m²

SVR

↑

CVP

↑

PAOP (PCWP)

↑ (>18 mmHg)

SvO₂ / ScvO₂

↓ (<60%)

Lactate

↑

Skin

Cold, clammy

Urine output

↓


Clinical Features

Symptoms

  • Severe dyspnea
  • Chest pain (ischemic cause)
  • Altered sensorium
  • Fatigue, collapse

Signs

  • Hypotension
  • Narrow pulse pressure
  • Cold extremities
  • Elevated JVP
  • Pulmonary crackles (LV failure)
  • New murmurs (acute MR, VSD)


Classification

SCAI Cardiogenic Shock Stages 

Stage

Clinical Description 

Hemodynamics

A – At Risk

Acute decompensated heart failure without hypoperfusion

Baseline end-organ function preserved

Normotensive

No shock physiology (normal hemodynamics)

B – Beginning (Pre-shock)

Relative/subclinical hypoperfusion

“Warm and wet” exam

SBP <90 mmHg, HR >100 bpm

Mild worsening renal function

CI >2.2 L/min/m²

C – Classic Cardiogenic Shock

Overt hypoperfusion requiring inotropes/vasopressors ± MCS

“Cold and wet” exam

SBP <90 mmHg

Lactate >2 mmol/L

LFTs ↑

Creatinine ↑ (>200%) or UOP <30 mL/h

CI <2.2 L/min/m²

PCWP >15 mmHg

RAP/PCWP >0.8

D – Deteriorating

Stage C with worsening despite therapy (medical or mechanical)

Persistent hypoperfusion

CI <2.2

PCWP >15

RAP/PCWP >0.8

E – Extremis

Cardiac arrest with ongoing CPR or on ECMO

Near pulseless state

Mechanical ventilation required

CI <2.2

PCWP >15

RAP/PCWP >0.8

 Stage C or beyond = true cardiogenic shock


Diagnostic Evaluation

Bedside

  • ECG (MI, arrhythmias)
  • ABG with lactate
  • Urine output
  • Focused echo (POCUS including vexus)
  • Chest x-ray

Laboratory

  • Troponin,BNP/NT-proBNP
  • Renal & liver function, electrolytes magnesium, phosphorous, coagulation profile, thyroid-stimulating hormone
  • Echocardiography 
  • Coronary angiography
  • Invasive Hemodynamics (PAC)

Useful when diagnosis unclear or refractory shock:

  • Confirms elevated PAOP with low CI
  • Differentiates mixed shock states


Management 

1. Immediate Stabilization

  • Airway & oxygenation (early NIV/intubation if pulmonary edema)
  • Continuous ECG & invasive BP monitoring
  • Two large bore IV lines / central access
  • Do not start beta-blockers


2. Optimize Preload

  • Avoid aggressive fluids
  • Small fluid challenge (250 mL per 15 to 30 minutes) only if hypovolemia suspected
  • Use echo-guided assessment


3. Vasopressors (FIRST-LINE)

Norepinephrine – Drug of Choice

  • Improves MAP with minimal tachycardia(but it can cause tachycardia and increased myocardial oxygen demand in patients with recent myocardial infarctions.)
  • Better outcomes than dopamine(↑ arrhythmias, ↑ mortality)

4. Inotropes

Drug

Dose

Use

Dobutamine

2.5-5 μg/kg/min

Low CO with adequate BP

Milrinone

0.25-0.375 μg/kg/min

Pulmonary HTN, RV failure

Levosimendan

Ca sensitizer

Selected cases

 Risk: hypotension, arrhythmias

5. Treat the Cause (MOST IMPORTANT)

AMI-Related CS

  • Immediate revascularization (PCI/CABG)
  • Guideline-mandated irrespective of delay

SHOCK (Should We Emergently Revascularize Occluded Coronaries for Cardiogenic Shock) trial data confirmed an approach that combines early revascularization with medical management in patients with cardiogenic shock is optimal.


6. Mechanical Circulatory Support (MCS)

Device

Mechanism

Indication

IABP

↓ afterload, ↑ coronary perfusion

Limited role

Impella

Direct LV unloading

Severe LV failure

VA-ECMO

Full cardiopulmonary support

Refractory shock

TandemHeart

LA-to-arterial

Advanced centers

Early MCS before multiorgan failure improves outcomes


REFERENCEES

1.Kosaraju A, Pendela VS, Hai O. Cardiogenic Shock. [Updated 2023 Apr 7]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2026 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK482255/

2.Washington manual Of Critical care

3.Irwin and Rippe’s Intensive Care Medicine