SCAI Releases Updated Expert Consensus on Shock Classification

January 31, 2022—The Society for Cardiovascular Angiography and Interventions (SCAI) announced the release of an expert consensus statement updating the SCAI shock classification that was first released in 2019.

The document, “SCAI Shock Stages Classification Expert Consensus Update: A Review and Incorporation of Validation Studies” by Srihari S. Naidu, MD, et al, is published simultaneously online in Journal of the Society for Cardiovascular Angiography & Interventions and Journal of the American College of Cardiology.

The statement was endorsed in December 2021 by the American College of Cardiology, American College of Emergency Physicians, American Heart Association, European Society of Cardiology, Association for Acute Cardiovascular Care, Society of Critical Care Medicine, International Society for Heart and Lung Transplantation, and the Society of Thoracic Surgeons. Together these organizations represent the diverse areas and related clinicians and surgeons where cardiogenic shock presents and is managed.

Dr. Naidu, Chair of the writing group, commented in the SCAI press release, “The new updated definition is easier to use, with tables that have eliminated relatively unnecessary variables and highlighted the more commonly present ones in each shock stage, a more useful cardiac arrest modifier, and a three-axis model that places the shock stages in context of other variables that need to be considered for the patient in front of you. Further, we have made it much clearer how patients move up and down the stages if they deteriorate or recover, what these changes do to survival, and how support strategies such as mechanical support devices or vasopressors tie into the various stages.” Dr. Naidu, a SCAI Trustee, is Director of the Cardiac Catheterization Laboratory at Westchester Medical Center in Valhalla, New York.

In the press release, SCAI noted that mortality from cardiogenic shock complicating myocardial infarction remains high, approaching or exceeding 50%, despite the development of percutaneous mechanical circulatory support technologies and the national standard of emergent angioplasty and stenting.

In May 2019, SCAI announced the original shock classification that was developed to provide a first-of-its-kind universal standardized vocabulary that would translate across settings and providers, including emergency room physicians, critical care physicians, heart failure physicians, interventional cardiologists, surgeons, and frontline providers such as emergency medical technicians.

SCAI stated that although the original system has been widely adopted for its simple and intuitive framework and ability to discern gradations of severity of cardiogenic shock for the first time, recent validation studies conducted since 2019 have provided new detailed information to make the definition more powerful.

According to SCAI, to produce the current update, the writing group reviewed validation studies of the original classification in detail to identify potential areas of refinement. The statement clarifies the precise role of the SCAI shock classification within a more comprehensive three-axis model, incorporating other predictors of mortality. These predictors include etiology and phenotype and nonmodifiable risk factors such as age and frailty. Additionally, the statement provides more granularity to the cardiac arrest modifier and the constituent domains of the classification, including physical examination, biochemical, and hemodynamic criteria. In addition, SCAI noted, the cardiac arrest modifier was adjusted based on available data to only include an arrest with concern for anoxic brain injury.

Timothy D. Henry, MD, Vice-Chair of the document’s writing group and President of SCAI, stated in the press release, “Cardiac arrest remains an important predictor of mortality in patients with cardiogenic shock, but we clarify the risk is in patients with unclear neurogenic status.”

SCAI and the endorsing societies anticipate the classification to continue to evolve over time as new data accrue but believe the updated criteria and associated tables and figures will be able to aid in acute clinical care for these patients, interhospital and within hospital communication, and in addition should facilitate clinical trials that will ultimately improve mortality in this high-risk population, reported the society in the press release.