What are the primary causes of cardiogenic shock?

Causes of Cardiogenic Shock

Primary Etiology

Acute myocardial infarction (AMI) is the most common cause of cardiogenic shock, complicating 7-10% of AMI cases and remaining the leading cause of mortality in these patients. 1, 2

Cardiac Causes

Ischemic Heart Disease

• Acute myocardial infarction represents the predominant etiology, typically requiring loss of >40% of left ventricular myocardium to precipitate shock 1, 2
• Extensive myocardial necrosis or stunned but viable myocardium both contribute to post-AMI shock 1
• The pathophysiology involves a vicious cycle where ischemia causes myocardial dysfunction, which further aggravates myocardial ischemia 3

Mechanical Complications of AMI

• Left ventricular free wall rupture is the most serious complication following AMI 1
• Ventricular septal rupture creates acute left-to-right shunting 1
• Papillary muscle rupture leading to acute severe mitral regurgitation 1
• Right ventricular infarction, most often associated with inferior AMI but rarely isolated 1

Valvular Heart Disease

• Severe valvular heart disease can precipitate cardiogenic shock, requiring emergency cardiac surgery as the gold standard, though percutaneous interventions are emerging 1
• Acute severe mitral regurgitation, either primary or secondary to LV dysfunction 1

Cardiomyopathy

• Acute decompensated heart failure in patients with pre-existing cardiomyopathy 1, 2
• Acute-on-chronic heart failure exacerbations 1
• Myocarditis causing acute myocardial inflammation and dysfunction 1

Arrhythmias and Conduction Disorders

• Atrial fibrillation is present in nearly 20% of cardiogenic shock patients 1
• Severe tachyarrhythmias or bradyarrhythmias causing hemodynamic compromise 1
• Conduction disorders associated with hemodynamic instability 1

Other Cardiac Causes

• Pericardial disease including cardiac tamponade, which can cause cardiogenic shock even with minimal pericardial collection if accumulation is rapid (e.g., RV perforation during pacing) 1
• Myocardial contusion from trauma 1
• Post-cardiotomy cardiogenic shock following cardiac surgery 4

Non-Ischemic Structural Causes

• Acute aortic dissection with involvement of coronary ostia or causing acute aortic regurgitation 1

Hemodynamic Characteristics

The underlying cardiac pathology results in:

• Decreased cardiac index (<2.2 L/min/m²) due to impaired contractility 5
• Elevated filling pressures (PCWP >15 mmHg, CVP >15 mmHg) from backward failure 5
• Increased systemic vascular resistance as a compensatory mechanism to maintain blood pressure 5
• This creates inadequate end-organ perfusion despite compensatory vasoconstriction 1

Clinical Pitfalls

Do not confuse late-stage septic shock with cardiogenic shock—septic shock can develop myocardial depression, but the primary hemodynamic pattern remains distributive with decreased SVR, whereas cardiogenic shock demonstrates elevated SVR 5

The rate of pericardial fluid accumulation matters more than volume—rapid accumulation (e.g., iatrogenic perforation) can cause shock with minimal fluid, while slow accumulation (e.g., malignancy) may be well-tolerated despite large volumes 1