SCAI refines cardiogenic shock classifications
The Society for Cardiovascular Angiography and Interventions (SCAI) released updated cardiogenic shock classifications to help clinicians better identify patients at risk, assess disease severity, and determine whether treatments are restoring adequate organ perfusion.
The 2026 SCAI SHOCK Classification Expert Consensus Update, published in the Journal of the SCAI (JSCAI) in conjunction with the 2026 American Heart Association (AHA) Scientific Sessions, represents the third iteration of the classification system first introduced in 2019.[1] The framework has become widely adopted in clinical care, research and regulatory settings as a common language for communicating cardiogenic shock severity.
Srihari Naidu, MD, FACC, FAHA, MSCAI, immediate-past SCAI president and director of the catheterization laboratories at Westchester Medical Center, was a co-chair of the consensus writing group. He said the update retains the familiar five-stage classification, A through E, while refining how clinicians identify patients at risk of deterioration and evaluate their response to treatment. Originally issued in 2019 and revised in 2022, this new iteration incorporates additional data from the past few years.
"We were happy that most of the data that had supported the shock classification and showed that really it was instrumental in improving shock care and really tracking with mortality. This is the third iteration of the shock classification, and I think people will agree that this has been a major step forward," he said.
One of the most important clarifications is the emphasis on tissue hypoperfusion rather than blood pressure alone when determining shock severity.
"Perfusion is what defines classic shock," Naidu explained, noting that patients in Stage B may have hypotension but still maintain adequate organ perfusion. Evidence of hypoperfusion, including altered mental status or cold and clammy extremities, places patients in Stage C.
The updated framework also places greater emphasis on lactate as a marker of inadequate perfusion, reflecting its increasingly routine use in cardiogenic shock assessment.
Another significant refinement involves Stage A, which previously encompassed a broad population of patients with underlying cardiac conditions who could potentially progress to shock. The revised classification provides more granular phenotypes to identify patients with heightened propensity for deterioration.
These include patients with coronary artery disease, ventricular tachycardia and other electrophysiology conditions, and valvular disease. Better defining these populations could help researchers design clinical trials targeting specific groups before they progress to more severe shock.
The update also clarifies Stage D, which represents patients whose condition is deteriorating or who are not responding adequately to initial treatment. Previously, the emphasis was largely on patients getting progressively worse. The revised definition also captures patients who are not improving despite intervention and continue to show evidence of inadequate perfusion.
Naidu said tracking a patient's trajectory through the stages is important because patients who improve and move down the classification scale have better survival. Recognizing patients who fail to improve is therefore essential for identifying those who may need additional intervention.
“A stage assigned at presentation should be reassessed at regularly defined intervals as the patient's condition changes, and the update
emphasizes that trajectory over time typically provides greater prognostic value than a single assessment," explained David A. Baran, MD, FSCAI, co-chair of the consensus writing group in a statement.
The consensus document expands the clinical information used to assess patients, incorporating a core data set that includes physical examination findings, biochemical markers, hemodynamics, electrocardiograms and point-of-care ultrasound. Ultrasound is particularly important because it can help clinicians diagnose shock and distinguish between different underlying causes.
The update also provides more detailed guidance for different cardiogenic shock phenotypes, including acute myocardial infarction-related, heart failure-related, valvular, right ventricular-predominant and mixed shock, as well as pulmonary embolism-related and pediatric shock.
Naidu emphasized that these conditions should not necessarily be approached as the same disease, because their underlying mechanisms, treatment options and outcomes can differ.
The consensus further reinforces the importance of multidisciplinary shock teams, recognizing that patients may develop shock in emergency departments, intensive care units or catheterization laboratories. Clinicians across these settings need a common understanding of shock severity and the ability to communicate changes in a patient's condition during transfers and handoffs.
Beyond immediate clinical care, Naidu said the updated classification could help shape future research by allowing investigators and medical device companies to focus on specific stages and patient phenotypes.
For example, researchers could investigate whether particular mechanical circulatory support strategies are most beneficial in Stage B, C or D patients, or whether interventions in earlier stages can prevent progression to more severe shock.
He pointed to the need for more targeted studies across the classification, including research into therapies for patients with ventricular tachycardia, high-risk percutaneous coronary intervention and acute myocardial infarction.
By providing more precise definitions of patient populations, the classification could also improve clinical trial design and registry research.
Naidu described the update as an important step toward unifying the field around a common framework while identifying areas where more evidence is needed.
The consensus was endorsed by the American College of Cardiology, AHA, Heart Failure Society of America, Society of Critical Care Medicine, Society of Thoracic Surgeons and other cardiovascular and critical care organizations.
Dave Fornell has covered healthcare for more than 17 years, with a focus in cardiology and radiology. Fornell is a 5-time winner of a Jesse H. Neal Award, the most prestigious editorial honors in the field of specialized journalism. The wins included best technical content, best use of social media and best COVID-19 coverage. Fornell was also a three-time Neal finalist for best range of work by a single author. He produces more than 100 editorial videos each year, most of them interviews with key opinion leaders in medicine. He also writes technical articles, covers key trends, conducts video hospital site visits, and is very involved with social media. E-mail: [email protected]