Srihari Naidu, MD, FACC, FAHA, FSCAI, discusses modifications to the SCAI shock stages that refine them to be even more useful and help clarify which patients go to which stages. Presenting on behalf of the SCAI Shock Classification Clinical Expert Writing Group, he explains that while shock severity—incorporating hemodynamics, metabolic derangements, and vasopressor toxicity—is important, it’s not the whole picture and there were other factors to consider.

Dr. Naidu describes a three-axis model of cardiogenic shock that, in addition to shock severity, also considers risk modifiers (eg, age, comorbidities, organ failure, frailty) and phenotype and etiology (eg, right, left, or biventricular dysfunction, cardiac vs. cardiopulmonary failure, congestion profile). “Mortality prediction is not just the stage,” he emphasizes, “it’s also these other things.” To reflect this, Dr. Naidu explains how the SCAI stages in the pyramid now have color gradation that merges into the next stage, indicating that those risk modifiers are very important.

Dr. Naidu also explains that another important improvement in the classification is an adjustment of the cardiac arrest modifier. “It turns out, based on the literature, that really only an arrest that causes a risk of anoxic encephalopathy is a problem. So that’s usually a Glasgow Coma Scale less than nine. Someone who’s not responding to the stimuli.”

Important updates were also made to the table describing exam findings, biochemical markers, and hemodynamics, which now provides criteria for what is typically present and what may be present. Dr. Naidu explains that this should enable people to rapidly stratify patients and be more consistent in that stratification across the globe.

Dr. Naidu also discusses a figure with recovery pathways and deterioration pathways up and down the stages. “One of the challenges to the SCAI shock stages is that people didn’t really understand in real life how do patients move through this. Can they move up it? Can they move down it? How do you determine the intervention? What happens if somebody’s still on a support device and you go down and the perfusion improves? Are they still a C, or not? So, we wanted to add some clarity there.” Dr. Naidu emphasizes, “Any acute catastrophic event can land you right at E… But everybody else has to go through C. So, C is a pivotal shock stage because you have to get to C and do an intervention before you get to D.”