A novel “structured clinically actionable framework” for defining Society for Cardiovascular Angiography and Interventions (SCAI) stages of cardiogenic shock (CS) severity was proposed Monday, based on a study of one of the largest multicenter CS registries in the U.S.
The study’s authors, led by Navin K. Kapur, MD, from Tufts Medical Center, Boston, also highlighted two predominating phenotypes pf CS.
The findings were published Monday online ahead of the July 19 issue of the Journal of the American College of Cardiology.
CS is a complex, multifactorial syndrome associated with high morbidity and mortality, the researchers said. Mixed etiologies, phenotypes, and clinical presentations, and importantly the lack of consistency among parameters used to accurately assess shock severity, have led to varied treatment results for the condition, they added.
Risk stratification for CS patients is, thus, a major unmet need, the researchers said, noting that the recently proposed SCAI staging system for CS severity – ranging from A “at risk” to E “extreme” – lacks uniformity.
“Although the SCAI classification system emphasizes a variety of physical examination findings, laboratory markers, and hemodynamics to stratify patients into various stages of shock severity, the lack of uniform, granular criteria to define hypotension and hypoperfusion may limit its clinical utility,” they said.
Previous research associates the number of vasopressors, inotropes and acute mechanical circulatory support (AMCS) devices used during hospitalization with increasing mortality and worsening congestion, the researchers said.
However, limited information on handling normotensive patients with hypoperfusion remains a key barrier to the application of SCAI stages in clinic, while the impact of temporal progression of severity of shock based on SCAI stages on mortality also remains poorly understood, they stressed.
The current paper, therefore, aimed to define SCAI stages more clearly at the time of presentation and throughout hospitalization using data from the Cardiogenic Shock Working Group (CSWG) registry, including patients from 17 U.S. hospitals enrolled between 2016 and 2021.
A total 3,455 CS patients were included. Of these, the cause of CS was myocardial infarction (MI) in 1,110, heart failure (HF) in 1,790 of whom heart failure (HF), and other causes in 16%.
The majority of the overall group was male (70.5%), white (59.1%), and had a history of hypertension (54.2%). The mean age was 61.6 years, and mean body mass index was 28.4 kg/m2.
Of the overall baseline cohort, 1,055 (30.5%) did not survive, totaling 449 (40.5%) of the MI group and 221 (24.6%) of the HF group (P < 0.001).
Patient demographic, laboratory and hemodynamic data were collected at a single time point “as close to admission as possible,” and across clinically relevant hospitalization time points, including; : first vasopressor/inotrope administration, first ever mechanical circulatory support placement, pulmonary artery catheter placement, 24 hours after last device placement, and discharge.
CS diagnosis as adjudicated by a physician was designated as a sustained episode at least one of the following; systolic blood pressure (SBP) <90 mm Hg for at least 30 minutes, use of vasoactive agents to maintain SBP, cardiac index <2.2 L/min/m2 in the absence of hypovolemia, each determined to be secondary to cardiac dysfunction, or use of an AMCS device for clinically suspected CS.
Findings and new framework
The researchers defined two key phenotypes of CS: that caused by MI (MI-CS) and that caused by HF (HF-CS). In-hospital mortality for the total study cohort was 35% and was significantly higher in the MI-CS cohort than HF-CS (42% vs. 25%; P < 0.0001).
They found a significant association between out-of-hospital cardiac arrest (OHCA) and mortality, with 52% of those patients dying in hospital, compared to 29% of those who did not suffer OHCA (P < 0.05).
The researchers also found a direct association of increasing treatment intensity – based on the number of drug and/or acute mechanical circulatory support device treatments received during index hospitalization – and mortality in the 3,167 patients with known drug and device data (odds ratio [OR]: 2.304; 95% confidence interval [CI]: 2.13-2.49; P < 0.001).
A similar association was observed among the HF-CS (OR: 2.430; 95% CI: 2.17-2.72; P < 0.001) and MI-CS groups (OR: 2.039; 95% CI: 1.80-2.32; P < 0.001).
Based on consensus among CSWG investigators, select clinical parameters of hypotension and hypoperfusion were also identified and demonstrated a significant association with mortality.
Meanwhile, SBP, lactate level, alanine transaminase level, and systemic pH were significantly associated with mortality and used to define each stage.
The investigators defined SCAI stages retrospectively at the data coordinating center, defining:
- Stage B as having either isolated hypoperfusion (lactate 2-5 mmol/L or alanine transaminase (ALT) 200-500 U/L) or hypotension (SBP 60-90 mm Hg or mean arterial pressure (MAP) 50-65 mm Hg) without the need for drug or device therapy.
- Stage C as having hypoperfusion and hypotension (using Stage B criteria), receiving 1 CS drug therapy, or 1 circulatory support device.
- Stage D as having hypotension (SBP 60-90 mm Hg or MAP 50-65 mm Hg) and hypoperfusion (lactate 5-10 mmol/L or ALT >500 U/L) or the need for two to dive drugs or devices. Those classified as stage D also included patients on one drug or device with hypotension or hypoperfusion that persisted despite treatment.
- SCAI stage E as having hypotension (SBP 10 mmol/L or pH ≤2) or the need for >3 drugs or three devices. All patients who experienced OHCA were included in stage E.
“We show that by employing a uniform definition for SCAI stages, we can begin to understand the clinical trajectories of CS in 2 predominating phenotypes and the association of drug or device therapy in this vulnerable population,” the researchers said.
“This approach may improve clinical application of the staging system and provides new insight into the trajectory of hospitalized CS patients.”
The analysis is an “important step forward” in refining and standardizing clinical classifications for CS prognosis, said Brigham and Women’s Hospital, and Harvard Medical School’s Ajar Kochar, MD, MHS, and colleagues in an accompanying editorial.
They stressed the need to further investigate the effects of shock severity over time.
“Ultimately, CS risk stratification tools will need to balance simplicity, clinical applicability, and optimal predictive performance,” the editorialists concluded.
“Once definitions for the classification of CS severity have been optimized and prospectively validated, they are likely to inform clinical trial eligibility criteria and guide clinical care at the bedside for years to come.”
Kapur NK, Kanwar M, Sinha SS, et al. Criteria for Defining Stages of Cardiogenic Shock Severity. J Am Coll Cardiol 2022;80:185-198.
Kochar A, Smilowitz NR, Hochman JS. Dynamic Cardiogenic Shock Classification: 2 Steps Forward, 1 Step Back. J Am Coll Cardiol 2022;80:199-201.
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