SCAI SHOCK Stage Classification Expert Consensus Update: A Review and Incorporation of Validation Studies

Abstract

A Warm Welcome to The First Issue of JSCAIJournal of the Society for Cardiovascular Angiography & InterventionsVol. 1Issue 1100013PreviewIt is my great privilege to have been entrusted with the launch of the Journal of the Society for Cardiovascular Angiography and Interventions (JSCAI). JSCAI is a powerful vehicle for authors to contribute and disseminate new clinical and scientific evidence related to all aspects of interventional cardiovascular medicine. As we release our first issue of the JSCAI, I hope you will enjoy the content and be motivated to contribute to our interventional community by submitting your next scientific manuscript. Full-Text PDF Open AccessThe Changing Landscape of Cardiogenic Shock: One Step Closer to Speaking a Common TongueJournal of the Society for Cardiovascular Angiography & InterventionsVol. 1Issue 1100012Preview“Progress is impossible without change, and those who cannot change their minds cannot change anything.” George Bernard Shaw (1944) Full-Text PDF Open Access Since its development and release in 2019, the Society for Cardiovascular Angiography and Interventions (SCAI) shock stage classification for adult patients has been widely cited and increasingly incorporated, owing to its simplicity across all clinical settings, easily understood and visualized framework, and notable endorsement by relevant societies and organizations that manage cardiogenic shock (CS).1Baran D.A. Grines C.L. Bailey S. et al.SCAI clinical expert consensus statement on the classification of cardiogenic shock.Catheter Cardiovasc Interv. 2019; 94: 29-37PubMed Google Scholar Ensuing validation studies over the course of the subsequent 2 ​years documented both its ease and rapidity of use as well as its ability to meaningfully discriminate patient risk across the spectrum of CS, including various phenotypes, presentations, and health care settings. Nonetheless, several areas of potential refinement have been identified to make the classification scheme more applicable across all settings and clinical time points, given that data from validation studies have provided useful information not previously available that could serve to significantly refine the classification. With this background, a clinical expert consensus writing group of all relevant stakeholders was reconvened to re-evaluate and refine the SCAI SHOCK stage classification based on the existing literature and clinician feedback from real-world experience. 1.The SCAI SHOCK stage is an indication of shock severity and comprises one component of mortality risk prediction in patients with CS, along with etiology/phenotype and other risk modifiers; a 3-axis model of risk stratification in CS has been proposed to position the SCAI SHOCK stage in context.2.Validation studies have underscored the correlation of the SCAI SHOCK stage with mortality across all clinical subgroups, including CS with and without acute coronary syndrome (ACS), cardiac intensive care unit (CICU) patients, and those presenting with out-of-hospital cardiac arrest (OHCA).3.Progression across the SCAI SHOCK stage continuum is a dynamic process, incorporating new information as available, and patient trajectories are important both for communication among clinicians and for decision-making regarding the next level of care and therapeutics.4.A hub and spoke model for transfer of higher-risk patients including those with a deteriorating SCAI SHOCK stage has been proposed.5.Cardiac arrest (CA) as described herein relates to that accompanied by coma, defined as the inability to respond to verbal stimuli, most commonly associated with Glasgow Coma Scale <9, where there is concern for significant anoxic brain injury.6.The SCAI SHOCK pyramid and associated figure now reflect gradations of severity within each stage and pathways by which patients progress or recover.7.A streamlined table incorporating variables that are most typically seen, and the revised CA modifier definition, is also provided and incorporates lessons learned from validation studies and clinician experience.8.The lactate level and thresholds have been highlighted to detect hypoperfusion but may be dissociated from hemodynamics in cases such as chronic heart failure (HF). In addition, patients may demonstrate other manifestations of end-organ hypoperfusion with a normal lactate level, and there are also important causes of an elevated lactate level other than shock. This statement has been developed as per SCAI Publications Committee policies for writing group composition, disclosure and management of relationships with industry, internal and external review, and organizational approval.2Szerlip M. Feldman D.N. Aronow H.D. et al.SCAI publications committee manual of standard operating procedures.Catheter Cardiovasc Interv. 2020; 96: 145-155Crossref PubMed Scopus (4) Google Scholar The writing group has been organized to ensure diversity of perspectives and demographics, multistakeholder representation, and appropriate balance of relationships with industry. Relevant author disclosures are included in Supplemental Table S1. Before appointment, members of the writing group were asked to disclose financial and intellectual relationships from the 12 ​months before their nomination. A majority of the writing group disclosed no relevant, significant financial relationships. Financial and intellectual disclosure information was periodically reviewed by the writing group during document development and updated as needed. SCAI policy requires that writing group members with a current, relevant financial interest are recused from participating in related discussions or voting on recommendations. The work of the writing committee was supported exclusively by the SCAI, a nonprofit medical specialty society, without commercial support. Writing group members contributed to this effort on a volunteer basis and did not receive payment from the SCAI. Narrative literature searches were performed by group members designated to lead each section, and initial findings were synthesized in section drafts authored primarily by the section leads in collaboration with other members of the writing group. Recommendations were iteratively discussed by the full writing group in a series of virtual consensus meetings until a majority of group members agreed on the text and qualifying remarks. In addition, all recommendations are supported by a short summary of the evidence or specific rationale. The draft manuscript was peer reviewed in October 2021, and the document was revised to address pertinent comments. The writing group unanimously approved the final recommendations and updated classification. The SCAI Publications Committee and Executive Committee endorsed the document as official society guidance in December 2021. SCAI statements are primarily intended to help clinicians make decisions about treatment alternatives. Clinicians also must consider the clinical presentation, setting, and preferences of individual patients to make judgments about the optimal approach. Since the publication of the SCAI SHOCK stage classification in 2019, several groups have produced observational validation studies ranging in size from 166 to 10004 patients that uniformly demonstrate an association between the SCAI SHOCK stage and mortality risk in a variety of populations (Table 1).1Baran D.A. Grines C.L. Bailey S. et al.SCAI clinical expert consensus statement on the classification of cardiogenic shock.Catheter Cardiovasc Interv. 2019; 94: 29-37PubMed Google Scholar,3Schrage B. Dabboura S. Yan I. et al.Application of the SCAI classification in a cohort of patients with cardiogenic shock.Catheter Cardiovasc Interv. 2020; 96: E213-E219Crossref PubMed Scopus (64) Google Scholar, 4Baran D.A. Long A. Badiye A.P. Stelling K. Prospective validation of the SCAI shock classification: single center analysis.Catheter Cardiovasc Interv. 2020; 96: 1339-1347Crossref PubMed Scopus (21) Google Scholar, 5Thayer K.L. Zweck E. Ayouty M. et al.Invasive hemodynamic assessment and classification of in-hospital mortality risk among patients with cardiogenic shock.Circ Heart Fail. 2020; 13: e007099Crossref PubMed Scopus (53) Google Scholar, 6Hanson I.D. Tagami T. Mando R. et al.SCAI shock classification in acute myocardial infarction: insights from the National Cardiogenic Shock Initiative.Catheter Cardiovasc Interv. 2020; 96: 1137-1142Crossref PubMed Scopus (28) Google Scholar, 7Jentzer J.C. Schrage B. Holmes D.R. et al.Influence of age and shock severity on short-term survival in patients with cardiogenic shock.Eur Heart J Acute Cardiovasc Care. 2021; 10: 604-612Crossref PubMed Google Scholar, 8Jentzer J.C. van Diepen S. Barsness G.W. et al.Cardiogenic shock classification to predict mortality in the cardiac intensive care unit.J Am Coll Cardiol. 2019; 74: 2117-2128Crossref PubMed Scopus (161) Google Scholar, 9Jentzer J.C. Baran D.A. van Diepen S. et al.Admission Society for Cardiovascular Angiography and Intervention shock stage stratifies post-discharge mortality risk in cardiac intensive care unit patients.Am Heart J. 2020; 219: 37-46Crossref PubMed Scopus (30) Google Scholar, 10Lawler P.R. Berg D.D. Park J.-G. et al.The range of cardiogenic shock survival by clinical stage: data from the Critical Care Cardiology Trials Network registry.Crit Care Med. 2021; 49: 1293-1302PubMed Google Scholar, 11Pareek N. Dworakowski R. Webb I. et al.SCAI cardiogenic shock classification after out of hospital cardiac arrest and association with outcome.Catheter Cardiovasc Interv. 2021; 97: E288-E297Crossref PubMed Scopus (14) Google Scholar Although several studies have focused on patients with CS,3Schrage B. Dabboura S. Yan I. et al.Application of the SCAI classification in a cohort of patients with cardiogenic shock.Catheter Cardiovasc Interv. 2020; 96: E213-E219Crossref PubMed Scopus (64) Google Scholar, 4Baran D.A. Long A. Badiye A.P. Stelling K. Prospective validation of the SCAI shock classification: single center analysis.Catheter Cardiovasc Interv. 2020; 96: 1339-1347Crossref PubMed Scopus (21) Google Scholar, 5Thayer K.L. Zweck E. Ayouty M. et al.Invasive hemodynamic assessment and classification of in-hospital mortality risk among patients with cardiogenic shock.Circ Heart Fail. 2020; 13: e007099Crossref PubMed Scopus (53) Google Scholar, 6Hanson I.D. Tagami T. Mando R. et al.SCAI shock classification in acute myocardial infarction: insights from the National Cardiogenic Shock Initiative.Catheter Cardiovasc Interv. 2020; 96: 1137-1142Crossref PubMed Scopus (28) Google Scholar, 7Jentzer J.C. Schrage B. Holmes D.R. et al.Influence of age and shock severity on short-term survival in patients with cardiogenic shock.Eur Heart J Acute Cardiovasc Care. 2021; 10: 604-612Crossref PubMed Google Scholar others have included a broader mix of CICU patients8Jentzer J.C. van Diepen S. Barsness G.W. et al.Cardiogenic shock classification to predict mortality in the cardiac intensive care unit.J Am Coll Cardiol. 2019; 74: 2117-2128Crossref PubMed Scopus (161) Google Scholar, 9Jentzer J.C. Baran D.A. van Diepen S. et al.Admission Society for Cardiovascular Angiography and Intervention shock stage stratifies post-discharge mortality risk in cardiac intensive care unit patients.Am Heart J. 2020; 219: 37-46Crossref PubMed Scopus (30) Google Scholar, 10Lawler P.R. Berg D.D. Park J.-G. et al.The range of cardiogenic shock survival by clinical stage: data from the Critical Care Cardiology Trials Network registry.Crit Care Med. 2021; 49: 1293-1302PubMed Google Scholar or those with OHCA.11Pareek N. Dworakowski R. Webb I. et al.SCAI cardiogenic shock classification after out of hospital cardiac arrest and association with outcome.Catheter Cardiovasc Interv. 2021; 97: E288-E297Crossref PubMed Scopus (14) Google Scholar As expected, the prevalence of each SCAI SHOCK stage varied with the population studied and the definitions used in each study (Fig. 1). The observed short-term (in-hospital or 30-day) mortality also varied depending on the population, and higher SCAI SHOCK stages were consistently associated with higher short- and long-term mortality (Fig. 2).4Baran D.A. Long A. Badiye A.P. Stelling K. Prospective validation of the SCAI shock classification: single center analysis.Catheter Cardiovasc Interv. 2020; 96: 1339-1347Crossref PubMed Scopus (21) Google Scholar,8Jentzer J.C. van Diepen S. Barsness G.W. et al.Cardiogenic shock classification to predict mortality in the cardiac intensive care unit.J Am Coll Cardiol. 2019; 74: 2117-2128Crossref PubMed Scopus (161) Google Scholar,11Pareek N. Dworakowski R. Webb I. et al.SCAI cardiogenic shock classification after out of hospital cardiac arrest and association with outcome.Catheter Cardiovasc Interv. 2021; 97: E288-E297Crossref PubMed Scopus (14) Google Scholar Furthermore, the SCAI SHOCK stages provided stepwise mortality risk stratification within the subgroups of ACS/acute myocardial infarction (AMI), HF, and those with and without CA.5Thayer K.L. Zweck E. Ayouty M. et al.Invasive hemodynamic assessment and classification of in-hospital mortality risk among patients with cardiogenic shock.Circ Heart Fail. 2020; 13: e007099Crossref PubMed Scopus (53) Google Scholar,8Jentzer J.C. van Diepen S. Barsness G.W. et al.Cardiogenic shock classification to predict mortality in the cardiac intensive care unit.J Am Coll Cardiol. 2019; 74: 2117-2128Crossref PubMed Scopus (161) Google Scholar,11Pareek N. Dworakowski R. Webb I. et al.SCAI cardiogenic shock classification after out of hospital cardiac arrest and association with outcome.Catheter Cardiovasc Interv. 2021; 97: E288-E297Crossref PubMed Scopus (14) Google Scholar Most studies classified the SCAI SHOCK stage at a single time point, precluding an analysis of serial changes in stage over time. Importantly, real-time assignment of the SCAI SHOCK stage by the treating team was feasible and allowed for serial assessments.4Baran D.A. Long A. Badiye A.P. Stelling K. Prospective validation of the SCAI shock classification: single center analysis.Catheter Cardiovasc Interv. 2020; 96: 1339-1347Crossref PubMed Scopus (21) Google Scholar Stratification of mortality risk in the cited studies despite different criteria, populations, and therapies remained consistent, underscoring the strength of the classification scheme.Table 1Characteristics of studies validating the association between the SCAI SHOCK stage and mortality.StudyYears includedPopulationDesignPatients, nPrimary outcomeSchrage et al 2020aPatients with CS from the Schrage 2020 study were included in the Jentzer 2021 study, so only the nonduplicated patients are reported for the Jentzer 2021 study.2009-2017CS or large MIRetrospective single-center100730-day survivalBaran et al 20202019-2020CSProspective single-center16630-day survivalThayer et al 20202016-2019CSProspective multicenterbPatient enrollment in these studies was prospective, but the SCAI SHOCK stage was assigned retrospectively.1414In-hospital mortalityHanson et al 20202016-2019AMICSProspective multicenterbPatient enrollment in these studies was prospective, but the SCAI SHOCK stage was assigned retrospectively.300Survival to dischargeJentzer et al 2021aPatients with CS from the Schrage 2020 study were included in the Jentzer 2021 study, so only the nonduplicated patients are reported for the Jentzer 2021 study.2007-2015CSRetrospective single-center93430-day survivalJentzer et al 20192007-2015CICURetrospective single-center10,004In-hospital mortalityLawler et al 20212017-2019CICU or CSRetrospective multicenter1991In-hospital mortalityJentzer et al 20202007-2015CICU survivorsRetrospective single-center9096Postdischarge survivalPareek et al 20202012-2017OHCARetrospective single-center39330-day mortalityDuplicate data from the same cohort are not shown.AMICS, CS from acute myocardial infarction; CICU, cardiac intensive care unit; CS, cardiogenic shock; MI, myocardial infarction; OHCA, out-of-hospital cardiac arrest; SCAI, Society for Cardiovascular Angiography and Interventions.a Patients with CS from the Schrage 2020 study were included in the Jentzer 2021 study, so only the nonduplicated patients are reported for the Jentzer 2021 study.b Patient enrollment in these studies was prospective, but the SCAI SHOCK stage was assigned retrospectively. Open table in a new tab Fig. 2Short-term mortality as a function of SCAI SHOCK stages in each study. ∗denotes that no deaths were observed in patients with SCAI stage B in these studies. CICU, cardiac intensive care unit; OHCA, out-of-hospital cardiac arrest; SCAI, Society for Cardiovascular Angiography and Interventions.View Large Image Figure ViewerDownload Hi-res image Download (PPT) Duplicate data from the same cohort are not shown. AMICS, CS from acute myocardial infarction; CICU, cardiac intensive care unit; CS, cardiogenic shock; MI, myocardial infarction; OHCA, out-of-hospital cardiac arrest; SCAI, Society for Cardiovascular Angiography and Interventions. Each study used different criteria to define the SCAI SHOCK stages (Supplemental Tables S2-S7), including various combinations of clinical variables based on the availability of data.3Schrage B. Dabboura S. Yan I. et al.Application of the SCAI classification in a cohort of patients with cardiogenic shock.Catheter Cardiovasc Interv. 2020; 96: E213-E219Crossref PubMed Scopus (64) Google Scholar, 4Baran D.A. Long A. Badiye A.P. Stelling K. Prospective validation of the SCAI shock classification: single center analysis.Catheter Cardiovasc Interv. 2020; 96: 1339-1347Crossref PubMed Scopus (21) Google Scholar, 5Thayer K.L. Zweck E. Ayouty M. et al.Invasive hemodynamic assessment and classification of in-hospital mortality risk among patients with cardiogenic shock.Circ Heart Fail. 2020; 13: e007099Crossref PubMed Scopus (53) Google Scholar, 6Hanson I.D. Tagami T. Mando R. et al.SCAI shock classification in acute myocardial infarction: insights from the National Cardiogenic Shock Initiative.Catheter Cardiovasc Interv. 2020; 96: 1137-1142Crossref PubMed Scopus (28) Google Scholar,8Jentzer J.C. van Diepen S. Barsness G.W. et al.Cardiogenic shock classification to predict mortality in the cardiac intensive care unit.J Am Coll Cardiol. 2019; 74: 2117-2128Crossref PubMed Scopus (161) Google Scholar,10Lawler P.R. Berg D.D. Park J.-G. et al.The range of cardiogenic shock survival by clinical stage: data from the Critical Care Cardiology Trials Network registry.Crit Care Med. 2021; 49: 1293-1302PubMed Google Scholar,11Pareek N. Dworakowski R. Webb I. et al.SCAI cardiogenic shock classification after out of hospital cardiac arrest and association with outcome.Catheter Cardiovasc Interv. 2021; 97: E288-E297Crossref PubMed Scopus (14) Google Scholar Five groups3Schrage B. Dabboura S. Yan I. et al.Application of the SCAI classification in a cohort of patients with cardiogenic shock.Catheter Cardiovasc Interv. 2020; 96: E213-E219Crossref PubMed Scopus (64) Google Scholar,5Thayer K.L. Zweck E. Ayouty M. et al.Invasive hemodynamic assessment and classification of in-hospital mortality risk among patients with cardiogenic shock.Circ Heart Fail. 2020; 13: e007099Crossref PubMed Scopus (53) Google Scholar,8Jentzer J.C. van Diepen S. Barsness G.W. et al.Cardiogenic shock classification to predict mortality in the cardiac intensive care unit.J Am Coll Cardiol. 2019; 74: 2117-2128Crossref PubMed Scopus (161) Google Scholar,10Lawler P.R. Berg D.D. Park J.-G. et al.The range of cardiogenic shock survival by clinical stage: data from the Critical Care Cardiology Trials Network registry.Crit Care Med. 2021; 49: 1293-1302PubMed Google Scholar,11Pareek N. Dworakowski R. Webb I. et al.SCAI cardiogenic shock classification after out of hospital cardiac arrest and association with outcome.Catheter Cardiovasc Interv. 2021; 97: E288-E297Crossref PubMed Scopus (14) Google Scholar developed study-specific SCAI SHOCK stage criteria, whereas two groups4Baran D.A. Long A. Badiye A.P. Stelling K. Prospective validation of the SCAI shock classification: single center analysis.Catheter Cardiovasc Interv. 2020; 96: 1339-1347Crossref PubMed Scopus (21) Google Scholar,6Hanson I.D. Tagami T. Mando R. et al.SCAI shock classification in acute myocardial infarction: insights from the National Cardiogenic Shock Initiative.Catheter Cardiovasc Interv. 2020; 96: 1137-1142Crossref PubMed Scopus (28) Google Scholar used physician assessment of the stage without study-specific criteria. Apart from the study by Baran et al which involved real-time prospective assignment of the stage by the treating team, each study assigned the stage retrospectively. The definitions of the SCAI SHOCK stages used in individual studies range from simple to complex.5Thayer K.L. Zweck E. Ayouty M. et al.Invasive hemodynamic assessment and classification of in-hospital mortality risk among patients with cardiogenic shock.Circ Heart Fail. 2020; 13: e007099Crossref PubMed Scopus (53) Google Scholar,8Jentzer J.C. van Diepen S. Barsness G.W. et al.Cardiogenic shock classification to predict mortality in the cardiac intensive care unit.J Am Coll Cardiol. 2019; 74: 2117-2128Crossref PubMed Scopus (161) Google Scholar For studies including patients with SCAI SHOCK stage B, this group was defined using vital sign abnormalities (Supplemental Table S4), and there was variability with respect to whether patients receiving vasopressors were classified as SCAI SHOCK stage B or C.3Schrage B. Dabboura S. Yan I. et al.Application of the SCAI classification in a cohort of patients with cardiogenic shock.Catheter Cardiovasc Interv. 2020; 96: E213-E219Crossref PubMed Scopus (64) Google Scholar, 4Baran D.A. Long A. Badiye A.P. Stelling K. Prospective validation of the SCAI shock classification: single center analysis.Catheter Cardiovasc Interv. 2020; 96: 1339-1347Crossref PubMed Scopus (21) Google Scholar, 5Thayer K.L. Zweck E. Ayouty M. et al.Invasive hemodynamic assessment and classification of in-hospital mortality risk among patients with cardiogenic shock.Circ Heart Fail. 2020; 13: e007099Crossref PubMed Scopus (53) Google Scholar,7Jentzer J.C. Schrage B. Holmes D.R. et al.Influence of age and shock severity on short-term survival in patients with cardiogenic shock.Eur Heart J Acute Cardiovasc Care. 2021; 10: 604-612Crossref PubMed Google Scholar,8Jentzer J.C. van Diepen S. Barsness G.W. et al.Cardiogenic shock classification to predict mortality in the cardiac intensive care unit.J Am Coll Cardiol. 2019; 74: 2117-2128Crossref PubMed Scopus (161) Google Scholar,10Lawler P.R. Berg D.D. Park J.-G. et al.The range of cardiogenic shock survival by clinical stage: data from the Critical Care Cardiology Trials Network registry.Crit Care Med. 2021; 49: 1293-1302PubMed Google Scholar,11Pareek N. Dworakowski R. Webb I. et al.SCAI cardiogenic shock classification after out of hospital cardiac arrest and association with outcome.Catheter Cardiovasc Interv. 2021; 97: E288-E297Crossref PubMed Scopus (14) Google Scholar Most studies used elevated lactate levels (≥2 ​mmol/L) to define hypoperfusion as stage C (Supplemental Table S5); impaired renal function was often used to define hypoperfusion, but few studies distinguished between acute and chronic renal dysfunction. Stage D shock was commonly defined as rising lactate and/or increasing vasopressor or mechanical circulatory support (MCS) requirements (Supplemental Table S6). Definitions of SCAI SHOCK stage E varied (Supplemental Table S7), with criteria including a high lactate level (≥5-10 ​mmol/L), a low pH (≤7.2), the need for multiple vasopressors/MCS devices, or the need for cardiopulmonary resuscitation (CPR). Despite the importance of physical examination and invasive hemodynamic assessment in defining CS clinically, these variables were not used in most studies because of retrospective data collection. Jentzer et al examined different definitions of shock and preshock in CICU patients and identified that hypoperfusion was associated with mortality to a greater extent than hypotension.12Jentzer J.C. Burstein B. Van Diepen S. et al.Defining shock and preshock for mortality risk stratification in cardiac intensive care unit patients.Circ Heart Fail. 2021; 14: e007678Crossref PubMed Scopus (8) Google Scholar To date, no published study has directly compared the performance of different SCAI SHOCK stage classification schemes in the same population for risk stratification. Importantly, the heterogeneity in mortality in each of the different stages across various studies likely reflects the dissimilar populations and different definitions used; more objective definitions and placing the SCAI SHOCK stage in the context of etiology, phenotype, and other nonmodifiable risk modifiers will help to optimize risk assessment in the future. However, the consistent stratification of risk (using different combinations of variables) suggests that refining and streamlining the criteria for the SCAI SHOCK stage as a categorization of shock severity will facilitate prospective assignment in clinical practice. The National Cardiogenic Shock Initiative reported on 300 patients with CS from AMI (AMICS) and determined the SCAI SHOCK stage by retrospective chart review, assigning the worst shock stage on admission and at 24 ​hours. The authors found an incremental but strong association between the shock stage and mortality at both time points.6Hanson I.D. Tagami T. Mando R. et al.SCAI shock classification in acute myocardial infarction: insights from the National Cardiogenic Shock Initiative.Catheter Cardiovasc Interv. 2020; 96: 1137-1142Crossref PubMed Scopus (28) Google Scholar Analyses from the Cardiogenic Shock Working Group included a broader group of patients with CS and defined the maximum shock stage during hospitalization, finding a stepwise increase in mortality with a higher shock stage in both patients with AMI and HF.5Thayer K.L. Zweck E. Ayouty M. et al.Invasive hemodynamic assessment and classification of in-hospital mortality risk among patients with cardiogenic shock.Circ Heart Fail. 2020; 13: e007099Crossref PubMed Scopus (53) Google Scholar Schrage et al reported on 1007 patients with mixed etiologies of CS and demonstrated mortality risk stratification across the shock stages (including at-risk patients with large AMI).3Schrage B. Dabboura S. Yan I. et al.Application of the SCAI classification in a cohort of patients with cardiogenic shock.Catheter Cardiovasc Interv. 2020; 96: E213-E219Crossref PubMed Scopus (64) Google Scholar Patients with CS from this cohort were combined with patients with CS from the Mayo Clinic cohort and reported similar findings.7Jentzer J.C. Schrage B. Holmes D.R. et al.Influence of age and shock severity on short-term survival in patients with cardiogenic shock.Eur Heart J Acute Cardiovasc Care. 2021; 10: 604-612Crossref PubMed Google Scholar Baran et al reported the first prospective validation study in patients with CS by having the treating physician assign the SCAI SHOCK stage in real time based on available clinical data.4Baran D.A. Long A. Badiye A.P. Stelling K. Prospective validation of the SCAI shock classification: single center analysis.Catheter Cardiovasc Interv. 2020; 96: 1339-1347Crossref PubMed Scopus (21) Google Scholar The studies by Hanson et al and Baran et al demonstrated that a rising or persistently elevated SCAI SHOCK stage was associated with substantially worse outcomes.4Baran D.A. Long A. Badiye A.P. Stelling K. Prospective validation of the SCAI shock classification: single center analysis.Catheter Cardiovasc Interv. 2020; 96: 1339-1347Crossref PubMed Scopus (21) Google Scholar,6Hanson I.D. Tagami T. Mando R. et al.SCAI shock classification in acute myocardial infarction: insights from the National Cardiogenic Shock Initiative.Catheter Cardiovasc Interv. 2020; 96: 1137-1142Crossref PubMed Scopus (28) Google Scholar Jentzer et al first validated the SCAI SHOCK stages using data from 10004 consecutive CICU patients at the Mayo Clinic, finding that each higher stage was associated with an incrementally higher risk of in-hospital mortality, even after adjustment for known predictors of mortality.8Jentzer J.C. van Diepen S. Barsness G.W. et al.Cardiogenic shock classification to predict mortality in the cardiac intensive care unit.J Am Coll Cardiol. 2019; 74: 2117-2128Crossref PubMed Scopus (161) Google Scholar Hospital survivors with a higher SCAI SHOCK stage on admission had increased postdischarge mortality.9Jentzer J.C. Baran D.A. van Diepen S. et al.Admission Society for Cardiovascular Angiography and Intervention shock stage stratifies post-discharge mortality risk in cardiac intensive care unit patients.Am Heart J. 2020; 219: 37-46Crossref PubMed Scopus (30) Google Scholar Patients with CA had a higher risk of dying at each SCAI SHOCK stage; both the location in which CA occurred (in-hospital versus out-of-hospital) and the rhythm of CA affected the risk of mortality.13Jentzer J.C. Henry T.D. Barsness G.W. Menon V. Baran D.A. Diepen S.V. Influence of cardiac arrest and SCAI shock stage on cardiac intensive care unit mortality.Catheter Cardiovasc Interv. 2020; 96: 1350-1359Crossref PubMed Scopus (29) Google Scholar A subsequent multicenter study from the CCCTN database in 1991 CICU patients with ACS or HF also demonstrated that the SCAI SHOCK stage was associated with in-hospital mortality; a diagnosis of CS was required for patients in SCAI stages C, D, and E.10Lawler P.R. Berg D.D. Park J.-G. et al.The range of cardiogenic shock survival by clinica