Cardiogenic Shock

Cardiogenic shock is a state of circulatory failure in which the heart cannot pump enough blood to meet the metabolic needs of the body, producing systemic hypoperfusion despite adequate or elevated filling pressures. It is the most lethal expression of acute cardiac dysfunction and most often complicates large myocardial infarction.

Definition

Cardiogenic shock is circulatory failure caused by primary cardiac (pump) dysfunction, characterized by sustained hypotension and signs of organ hypoperfusion in the presence of adequate intravascular volume and elevated cardiac filling pressures.

Scope

The entry covers the definition and hemodynamic profile of cardiogenic shock, its principal causes, the framework used to classify its severity, and the major trials that have shaped how it is understood. It is presented as a reference description of the syndrome within critical care and does not provide diagnostic criteria for individual patients or treatment instructions.

Core questions

• What distinguishes cardiogenic shock from other forms of shock?
• What are the most common causes of cardiogenic shock?
• How is the severity of cardiogenic shock classified?
• What does trial evidence show about revascularization and circulatory support in cardiogenic shock?

Key concepts

• Pump failure and low cardiac output
• Systemic hypoperfusion with elevated filling pressures
• Acute myocardial infarction as the leading cause
• SCAI shock stages
• Early revascularization
• Mechanical circulatory support in shock

Mechanisms

In cardiogenic shock, primary failure of the heart as a pump lowers cardiac output and, with it, the perfusion pressure available to organs, while filling pressures remain high because blood backs up behind the failing ventricle. Reduced output triggers neurohormonal and inflammatory responses that raise systemic vascular resistance and can further increase cardiac workload, creating a self-reinforcing spiral of falling perfusion, rising congestion, and progressive organ injury. The commonest trigger is loss of contractile myocardium in acute myocardial infarction, though mechanical complications, end-stage heart failure, arrhythmia, and other causes can produce the same physiology.

Clinical relevance

Cardiogenic shock is a defining circulatory emergency in critical care, and its hemodynamic profile illustrates how pump failure differs from vasodilatory or hypovolemic shock. This entry describes the syndrome and its evidence base as a reference; it does not provide criteria for diagnosing an individual patient or direction on management.

Epidemiology

Cardiogenic shock most often complicates acute myocardial infarction and, despite advances in revascularization, continues to carry high short-term mortality. Its incidence and outcomes vary with the underlying cause and with the timeliness of reperfusion and supportive care.

Evidence & guidelines

The SHOCK trial (Hochman et al., 1999) established the role of early revascularization in infarct-related cardiogenic shock; the IABP-SHOCK II trial (Thiele et al., 2012) found no survival benefit from routine intra-aortic balloon counterpulsation; and the DanGer Shock trial (Møller et al., 2024) examined a microaxial flow pump in this setting. The SCAI classification (Baran et al., 2019) provides a staging framework, and society guidelines such as the 2023 ESC acute coronary syndromes guideline (Byrne et al., 2023) synthesize the evidence.

History

Understanding of cardiogenic shock advanced as coronary reperfusion became feasible: the SHOCK trial in 1999 demonstrated a survival benefit from early revascularization, reframing the syndrome as potentially reversible. Subsequent trials tested mechanical support devices, often with neutral or contested results, and consensus efforts introduced staged classifications to standardize description and enable comparison across studies.

Debates

What is the role of mechanical circulatory support in cardiogenic shock?

Trials of intra-aortic balloon counterpulsation showed no survival benefit, while later trials of microaxial flow pumps and other devices have produced more nuanced results, leaving the optimal use of mechanical support an area of active investigation and debate.

Key figures

• Judith Hochman
• Holger Thiele
• Jacob Eifer Møller

Seminal works

• hochman-1999-shock
• thiele-2012-iabp
• baran-2019-scai

Frequently asked questions

How does cardiogenic shock differ from septic shock?

Cardiogenic shock results from failure of the heart to pump and is marked by low cardiac output with elevated filling pressures, whereas septic shock is a distributive state driven by vasodilation, so the two have different hemodynamic profiles.

What is the most common cause of cardiogenic shock?

Acute myocardial infarction with extensive loss of contractile myocardium is the leading cause, though mechanical complications, advanced heart failure, and arrhythmias can also produce it.