Acute cardiac hemodynamic instability may result from disorders that impair function of the myocardium, valves, conduction system, or pericardium, either in isolation or in combination.<unk>  is pragmatically defined as a state in which ineffective cardiac output caused by a primary cardiac disorder results in both clinical and biochemical manifestations of inadequate tissue perfusion. The clinical presentation is typically characterized by persistent hypotensionunresponsive to volume replacement and is accompanied by clinical features of end-organ hypoperfusion requiring intervention with pharmacological or mechanical support. Although not mandated, objective hemodynamic parameters for<unk>  can help confirm the diagnosis and enable comparison across cohorts and clinical trials. Definitions in clinical practice guidelines and operationalized definitions used in the SHOCK (Should We Emergently Revascularize Occluded Coronaries for<unk>  and IABP-SHOCK II (Intraaortic Balloon Pump in<unk>  II) trials.Before the routine use of early revascularization, MI-associated<unk>  had an in-hospital mortality exceeding 80%. A registry trial of 250 patients with acute MI described the association between bedside physical examination (Killip classification) for the assessment of heart failure (HF) and the risk of mortality. Patients with Killip class IV <unk>  had a mortality of 81%. Subsequently, the Diamond and Forrester classification using right-sided heart catheterization described the role of cardiac hemodynamics in stratifying risk after acute MI in the prereperfusion era. Patients in Diamond and Forrester subgroup IV with a pulmonary capillary wedge pressure (PCWP) >18 mm Hg and a cardiac index (CI) <2.2 L·min−1·m−2, indicative of<unk> , had a mortality of 51%. Treatment efforts to reduce mortality initially focused on improvement of hemodynamic parameters by mechanical devices. The intra-aortic balloon pump (IABP), introduced in a registry cooperative trial, decreased systolic blood pressure (SBP), increased diastolic blood pressure, and modestly but significantly increased CI. Nevertheless, mortality remained virtually unchanged, with only 15 survivors among 87 patients (83% mortality). The early reperfusion era did not affect outcomes for shock complicating acute MI. Fibrinolysis was effective for patients with ST-segment–elevation MI (STEMI) in general, but it is less clear if fibrinolysis reduces mortality in those with<unk> .The first major breakthrough in<unk>  treatment was achieved by the randomized SHOCK trial. Although an early invasive strategy coupled with percutaneous coronary intervention (PCI) or coronary artery bypass grafting (CABG) did not reduce 30-day mortality (the primary outcome of the trial), a significant mortality reduction emerged at 6 and 12 months that persisted at longer-term follow-up. Subsequent registries confirmed the survival advantage of early revascularization. Further efforts to reduce<unk>  mortality have been directed toward improvements in MCS devices. The largest randomized trial in patients with acute MI complicated by<unk>  did not show a benefit with routine IABP placement in addition to revascularization. As a result, there has been a decrease in the use of IABPs in clinical practice and a downgrading in guideline recommendations. Recently, other percutaneous MCS devices have shown promise in the treatment of<unk> , but more data from randomized clinical trials are needed.
Cardiogenic shock
Neurogenic shock
Obstructive shock
Spinal shock
Distributive shock
Acute chest syndrome
Cardiac tamponade
Tumor lysis syndrome