Cardiogenic shock is a high-acuity, potentially complex, and hemodynamically diverse state of end-organ hypoperfusion that is frequently associated with multisystem organ failure. Despite improving survival in recent years, patient morbidity and mortality remain high, and there are few evidence-based therapeutic interventions known to clearly improve patient outcomes. This scientific statement on cardiogenic shock summarizes the epidemiology, pathophysiology, causes, and outcomes of cardiogenic shock; reviews contemporary best medical, surgical, mechanical circulatory support, and palliative care practices; advocates for the development of regionalized systems of care; and outlines future research priorities. Cardiogenic shock (CS) is a low-cardiac-output state resulting in life-threatening end-organ hypoperfusion and hypoxia.1,2 Acute myocardial infarction (MI) with left ventricular (LV) dysfunction remains the most frequent cause of CS. 1,3 Advances in reperfusion therapy have been associated with improvements in survival, but significant regional disparities in evidence-based care have been reported, and in-hospital mortality remains high (27%-51%).1,4-9 Management recommendations are distributed between disease-specific statements and guidelines, and a dedicated and comprehensive clinical resource in this area is lacking. Thus, consolidating the evidence to define contemporary best medical and surgical CS practices for both MI-associated CS and other types of CS may be an important step in knowledge translation to help attenuate disparities in evidence-based care.Regional systems of care coupled with treatment algorithms have improved survival in high-acuity time-sensitive conditions such as MI, out-of-hospital cardiac arrest (OHCA), and trauma.10-12 Applying a similar framework to CS management may lead to similar improvements in survival, and CS systems of care are emerging within existing regional cardiovascular emergency care networks; however, guidance from a national expert group on structure and systems of care has not been available. 13,14 Accordingly, the purposes of this American Heart Association (AHA) scientific statement on CS are to summarize our contemporary understanding of the epidemiology, pathophysiology, and in-hospital best care practices into a single clinical resource document; to suggest a stepwise management algorithm that integrates medical, surgical, and mechanical circulatory support (MCS) therapies; and to propose a Mission: Lifelinesupported pathway for the development of integrated regionalized CS systems of care. DEFINITION OF CSAcute cardiac hemodynamic instability may result from disorders that impair function of the myocardium, valves, conduction system, or pericardium, either in isolation HISTORICAL PERSPECTIVESBefore the routine use of early revascularization, MIassociated CS 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 as...

Infarct size, measured by CMR or technetium-99m sestamibi SPECT within 1 month after primary PCI, is strongly associated with all-cause mortality and hospitalization for HF within 1 year. Infarct size may, therefore, be useful as an endpoint in clinical trials and as an important prognostic measure when caring for patients with STEMI.

The detection of elevated cardiac enzyme levels and the occurrence of electrocardiographic (ECG) abnormalities after revascularization procedures have been the subject of recent controversy. This report represents an effort to achieve a consensus among a group of researchers with data on this subject. Creatine kinase (CK) or CK-MB isoenzyme (CK-MB) elevations occur in 5% to 30% of patients after a percutaneous intervention and commonly during coronary artery bypass graft surgery (CABG). Although Q wave formation is rare, other ECG changes are common. The rate of detection is highly dependent on the intensity of enzyme and ECG measurement. Because most events occur without the development of a Q wave, the ECG will not definitively diagnose them; even the ECG criteria for Q wave formation signifying an important clinical event have been variable. At least 10 studies evaluating > 10,000 patients undergoing percutaneous intervention have demonstrated that elevation of CK or CK-MB is associated not only with a higher mortality, but also with a higher risk of subsequent cardiac events and higher cost. Efforts to identify a specific cutoff value below which the prognosis is not impaired have not been successful. Rather, the risk of adverse outcomes increases with any elevation of CK or CK-MB and increases further in proportion to the level of intervention. This information complements similar previous data on CABG. Obtaining preprocedural and postprocedural ECGs and measurement of serial cardiac enzymes after revascularization are recommended. Patients with enzyme levels elevated more than threefold above the upper limit of normal or with ECG changes diagnostic for Q wave myocardial infarction (MI) should be treated as patients with an MI. Patients with more modest elevations should be observed carefully. Clinical trials should ensure systematic evaluation for myocardial necrosis, with attention paid to multivariable analysis of risk factors for poor long-term outcome, to determine the extent to which enzyme elevation is an independent risk factor after considering clinical history, coronary anatomy, left ventricular function and clinical evidence of ischemia. In addition, tracking of enzyme levels in clinical trials is needed to determine whether interventions that reduce periprocedural enzyme elevation also improve mortality.

Cardiogenic shock (CS) remains the most common cause of death in patients with acute myocardial infarction although mortality could be reduced from formerly ∼80% to 40-50%. In addition to percutaneous coronary intervention or coronary artery bypass grafting, catecholamines, fluids, intraaortic balloon pumping (IABP), and also active assist devices are widely used for CS management. However, there is only limited evidence for any of the above treatments except for early revascularization and the relative ineffectiveness of IABP. This updated review will therefore outline the management of CS complicating acute myocardial infarction with major focus on evidence-based revascularization techniques, intensive care unit treatment including ventilation, transfusion regimens, adjunctive medication, and mechanical support devices.

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After accounting for baseline predictors of mortality, major bleeds and MI have similar overall strength of association with mortality in the first year after ACS. MI is correlated with a dramatic increase in short-term risk, whereas major bleeding correlates with a more prolonged mortality risk.

Copies: This document is available on the World Wide Web sites of the American College of Cardiology (www.cardiosource.org) and the American Heart Association (my.americanheart.org). A copy of the document is available at http://my.americanheart.org/statements by selecting either the "by Topic" link or the "by Publication Date" link. To purchase additional reprints, call 843-216-2533 or e-mail kelle.ramsay@wolterskluwer.com. expert peer review of AHA scientific statements is conducted by the AHA office of science operations. For more on AHA statements and guidelines development, visit http://my.americanheart.org/statements and select the "Policies and Development" link.

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