SCAI SHOCK Stage Classification Updated to Enhance Applicability in Clinical and Research Settings

November 5, 2021—The Society for Cardiovascular Angiography & Interventions (SCAI) announced that a newly developed expert consensus statement will provide updated guidance on the use of the SCAI SHOCK stage classification, a five-stage system intended to facilitate communication about the diagnosis, presentation, and evolving nature of cardiogenic shock (CS).

The updated classification was presented by SCAI Trustee Srihari S. Naidu, MD, during a featured session titled New Directions in Cardiogenic Shock at TCT 2021, the 33rd annual Transcatheter Cardiovascular Therapeutics scientific symposium of the Cardiovascular Research Foundation held November 4-6 online and in Orlando, Florida. Dr. Naidu is Director of the Cardiac Catheterization Laboratory at Westchester Medical Center in Valhalla, New York. SCAI anticipates publication of the manuscript in the coming months.

The document was developed in collaboration with the American College of Cardiology, American College of Emergency Physicians, American Heart Association, European Society of Cardiology Association for Acute Cardiovascular Care, Cardiac Safety Research Consortium, Society of Critical Care Medicine, and the Society of Thoracic Surgeons, each of which had representation on the writing group. The writing group was organized to ensure a diversity of perspectives and stakeholder representation and achieve multi-specialty consensus around the updated classification scheme, noted SCAI.

In 2019, the society developed and released the SHOCK Stages classification to provide a unified and standardized vocabulary that would translate across settings and providers (including, emergency room physicians, emergency medical services, critical care physicians, heart failure physicians, interventional cardiologists, and surgeons).

SCAI advised that although the system has been widely adopted for its simple and intuitive framework, and ability to discern gradations of severity of CS for the first time, recent validation studies conducted since 2019 have uncovered areas in need of refinement.

As outlined by SCAI, the updated classification's key points include:

• SCAI SHOCK Stage is an indication of shock severity and comprises one component of mortality risk prediction in CS patients, along with etiology/phenotype and other risk modifiers; a three-axis model of risk stratification in CS has been proposed to position SCAI SHOCK Stage in context.
• Validation studies have underscored the correlation of SCAI SHOCK Stage with mortality across all clinical subgroups, including CS with and without acute coronary syndrome, cardiac intensive care unit patients, and those presenting with out-of-hospital cardiac arrest.
• Progression across the SCAI SHOCK stages 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.
• A hub-and-spoke model for transfer of higher risk patients including those with deteriorating SCAI SHOCK Stage has been proposed.
• Cardiac arrest 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.
• The SCAI SHOCK pyramid and associated figure now reflect gradations of severity within each stage and pathways by which patients progress or recover.
• A streamlined table incorporating variables that are most typically seen, and the revised cardiac arrest modifier definition, is also provided and incorporates lessons learned from validation studies and clinician experience.
• Lactate level and thresholds have been highlighted to detect hypoperfusion but may be dissociated from hemodynamics in cases such as chronic heart failure. 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.

Dr. Naidu, who Chaired the current Writing Group as well as the original Writing Group in 2019 commented in the SCAI press release, "The new figures and updated table should leave less room for interpretation and enhance the standardization significantly, including placing the SCAI SHOCK Stages in context with other variables that must be evaluated when managing a patient with CS. We also highlight new lactate thresholds and provide needed clarification for the pivotal SCAI SHOCK Stage C and the cardiac arrest modifier."

Timothy Henry, MD, who is President of SCAI and Vice Chair of the Writing Group, added, "Studies continue to validate the SCAI SHOCK Stage classification as a tool to help clinicians and researchers better understand cardiogenic shock and offer guidance on treatment pathways to improve survival. The updated expert consensus will underscore the benefit of the classification system across a broad patient spectrum and provides meaningful changes that we believe will enhance both clinical care and future research."