New guidance on the diagnosis and presentation of cardiogenic shock aims to simplify and standardise the management of these patients from the emergency room to the cath lab.
Spearheaded by the Society for Cardiovascular Angiography and Interventions (SCAI) the new expert consensus statement centres on a five-stage classification system intended to provide clinicians and researchers with a “unified and standardised vocabulary” for cardiogenic shock, applicable across a range of healthcare settings. Additionally, the system aims to facilitate recognition of risk for adverse outcomes, potential for benefit from various interventions, and prognosis with the goal of reducing mortality.
SCAI Shock Stages builds upon a classification system first developed in 2019, designed for use by emergency room physicians and emergency medical services, critical care physicians, heart failure physicians, interventional cardiologists and surgeons. According to SCAI, though the system has been widely adopted for its simple framework and ability to discern gradations of severity of cardiogenic shock, recent validation studies conducted since 2019 have uncovered areas in need of refinement. A two-year update to the document was unveiled at the Transcatheter Cardiovascular Therapeutics annual meeting (TCT 2021; 4–6 November, Orlando, USA and virtual) by Srihari S Naidu (Westchester Medical Center, Valhalla, USA) who chaired the writing group tasked with developing the framework.
Cross-disciplinary buy-in has been an important aspect of the document’s development, and SCAI has sought to work collaboratively with the American College of Cardiology (ACC), American College of Emergency Physicians (ACEP), the American Heart Association (AHA), the European Society of Cardiology (ESC) Association for Acute Cardiovascular Care (ACVC), Cardiac Safety Research Consortium (CSRC), Society of Critical Care Medicine (SCCM) and the Society of Thoracic Surgeons (STS).
“This topic spans a lot of different colleagues all taking care of these patients, so I am very proud of that fact,” Naidu tells Cardiovascular News, referring to the diverse profile of organisations and experts involved in the drafting of the document’s latest version. “Having those organisations and critical care medicine endorse it will allow us to look at shock in all the different venues it occurs; be it at home, coming into the hospital, in the hospital, in the cath lab, in the critical care unit, or as they approach the surgeons.”
“From soup to nuts we have one language that allows us to speak to anybody on the shock team. Each hospital will be quite different in terms of who is on that team and what location the patient is at. That has been a real benefit of the definition initially, enabling us all to speak the same language, but now we would like to improve that same language and broaden the number of people who are speaking it.”
Naidu explains that the initial impetus for the project was to align the language, and therefore understanding, around the classification and treatment of cardiogenic shock. “The first questions were: ‘Are we talking about the same patients? How do we standardise so that we can generalise the findings of a trial to a patient population that we can more clearly envision?’”
The resulting output is a system that describes the stages of cardiogenic shock from A to E. Stage A is those “at risk” for cardiogenic shock, stage B is “beginning” shock, stage C is “classic” cardiogenic shock, stage D is “deteriorating”, and E is “extremis”. Naidu explains that this system aids the simple categorisation of patients, as well as helping to track the progression and regression of shock within these cases, thereby informing whether to escalate treatment. Visually, the grades are displayed in an easy-to-understand pyramid.
“By doing that it facilitates the shock team to assess the patient, understand what direction the patient is going in and quickly have different minds tell us how we are going to impact this to defervesce. I think that the real benefit is that you get the diagnosis quickly, the table allows us to say ‘these are the things that would show you that you are getting into D or E, so you have to look for these proactively’.”
While Naidu says he is encouraged by the take up of SCAI Shock so far, validation studies have informed the revisions and fine tuning that have gone into the second iteration of the document. Among the important points to have emerged from the studies is the correlation of SCAI Shock Stage with mortality across all clinical subgroups, including cardiogenic with and without acute coronary syndrome, cardiac intensive care unit (CICU) patients, and those presenting with out-of-hospital cardiac arrest (OHCA).
Commenting on this finding, Naidu says: “As you moved up the stage it was very clear that mortality increased. It did not matter if it was a cardiogenic shock patient, or a general CICU [cardiac intensive care unit] patient, which is a variety of non-ischaemic and ischaemic cardiomyopathy or advanced heart failure disease substrates, and it did not matter if the patient had an out-of-hospital cardiac arrest or not. In all of these patient populations, as you went up the pyramid, the mortality was statistically significantly increased.”
Among the updates to the document the SCAI Shock pyramid and associated figure now reflect gradations of severity within each stage, highlighting the variability based on risk modifiers within each stage, and pathways by which patients progress or recover. A streamlined table incorporating variables that are most typically seen, and a revised cardiac arrest modifier definition, is also provided and incorporates lessons learned from validation studies and clinician experience.
Lactate level and thresholds have also been highlighted to detect hypoperfusion but may be dissociated from haemodynamics 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.
SCAI also proposes to develop a hub and spoke model for transfer of higher-risk patients including those with deteriorating SCAI Shock Stage. “We know that not all hospitals have the same resources, in terms of personnel,” Naidu told Cardiovascular News, explaining that the ultimate aim is for cardiogenic shock patients to be directed at the first instance to the hospital where they can receive the most appropriate treatment. “That will be a huge benefit to society because it is less resource utilisation if you have the right patients for the right hospital using appropriate resources for the appropriate patients, which ultimately will be cost saving and hopefully also life-saving by avoiding unnecessary transfer delays.”
In terms of next steps, Naidu said he expects that analysis of the impact that this latest iteration of the document will shape future direction. “Future directions will have to be—is this truly applicable in all settings?” he said. We need to know that this works in the pre-hospital and emergency room settings, and whether we can incorporate this into protocols that guide therapies and save lives.”