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Criteria for Defining Stages of Cardiogenic Shock Severity
Quick Takes
- Based on the SCAI cardiogenic shock stages, a modified version using specific parameters and cutoffs to define hypotension, hypoperfusion, and treatment intensity was created to make classifying shock severity more uniform and applicable.
- The modified shock criteria predict in-hospital mortality, using both baseline and maximum shock stages.
- Shock stages frequently change and worsen during the hospitalization, with specific trajectories having different expected outcomes.
Study Questions:
For patients with cardiogenic shock (CS), can the Society for Cardiovascular Angiography and Intervention (SCAI) CS stages be refined by including specific parameters for hypotension, hypoperfusion, and treatment intensity to create a broadly applicable and uniform system for grading disease severity and predicting outcomes?
Methods:
The study used registry data from the Cardiogenic Shock Working Group (CSWG), which is a multicenter research consortium consisting of 17 clinical sites contributing data for patients hospitalized with CS. Patients from 2016–2020 were included in the analysis. Patients were excluded if mortality data at hospital discharge was not available. Etiology of CS was specified as secondary to acute myocardial infarction (MI), de novo or acute on chronic heart failure (HF), or other. Treatment intensity was defined by the number of vasoactive/inotropic drugs and acute mechanical circulatory support (AMCS) devices used. Using the SCAI CS staging framework, the study authors identified parameters to define severity of CS, which included presence of out-of-hospital cardiac arrest (OHCA), lactate level, alanine transaminase (ALT) level, systolic blood pressure (SBP) or mean arterial pressure (MAP), and systemic pH.
The following CSWG-refined SCAI stages were proposed (stages C, D, and E have multiple ways to meet stage criteria):
Stage B:
- Hypotension (SBP 60-90 mm Hg or MAP 50-65 mm Hg) OR hypoperfusion (lactate 2-5 mmol/L or ALT 200-500 U/L) + no drug/device therapy
Stage C:
- Hypotension AND hypoperfusion (same cutoffs) + no drug/device therapy
- 1 drug OR 1 device therapy without hypotension or hypoperfusion
Stage D:
- Hypotension (same cutoffs) AND worsened hypoperfusion (lactate 5-10 mmol/L or ALT >500 U/L)
- 2-5 drugs/devices therapies
- 1 drug or 1 device therapy with persistent hypotension or hypoperfusion
Stage E:
- Hypotension (SBP <60 mm Hg or MAP <50 mm Hg)
- Hypoperfusion (lactate >10 mmol/L or pH ≤7.2)
- >3 drug or >3 device therapies
- OHCA
Baseline CS stage and maximum stage during the hospitalization were identified. Time from baseline to maximum stage was identified. Associations with in-hospital mortality were made.
Results:
A total of 3,455 patients were included. Etiology of CS was identified as HF in 52% and MI in 32%. Overall, in-hospital mortality was 35%, though was higher for patients with MI compared to HF (42% vs. 25%) and OHCA compared to no OHCA (52% vs. 29%). Escalating vasoactive/inotropic drug and AMCS use was also associated with worse mortality. The prespecified parameters for hypotension (SBP, MAP) and hypoperfusion (lactate level, ALT, systemic pH) were significant predictors of in-hospital mortality on multivariate analysis.
Both baseline and maximum CS stage was associated with in-hospital mortality. Generally, higher stage CS at both baseline and maximum stage predicted worsened outcomes, except for stage C shock, which had numerically the lowest mortality rate. In examining the temporal changes in CS staging, lower baseline stages were associated with higher rates of stage escalation over the course of the hospitalization and shorter duration of time to maximum stage. Specifically, for baseline stage B shock, 90% developed worsened shock over the hospitalization with an average of 52 hours to reach maximum stage; for baseline stage C, 68% had stage escalation with an average of 103 hours to reach maximum; for stage D, 18% had stage escalation with an average of 178 hours to reach maximum.
Conclusions:
A CSWG-refined SCAI CS staging system using specific parameters and cutoffs to define hypotension, hypoperfusion, and treatment intensity can be used to predict in-hospital mortality based on baseline and maximum stages.
Perspective:
CS remains a heterogenous condition with an associated high mortality. This makes defining severity of CS a difficult but important task. Lacking from the original and updated version of the SCAI stage definitions is specific details on cutoffs or key parameters. The study authors sought to address this gap by providing a set of objective CS stage definitions that could be easily applied and are objective. Applying this to the CSWG registry data provided validation for this approach, demonstrating both abilities to predict in-hospital mortality and providing novel information on temporal changes in CS staging for individual patients through an index hospitalization. This is an important step in helping to better understand CS and providing uniform definitions for clinical and research use. Interestingly, stage C shock had a numerically lower mortality than stage B shock. The exact reasons for this observation are unclear but indicates that there are possible confounding variables and important predictors not accounted for in this model (such as renal function, drug dosing, and types of AMCS device used). Further studies are needed in this area.
Clinical Topics: Acute Coronary Syndromes, Arrhythmias and Clinical EP, Heart Failure and Cardiomyopathies, Invasive Cardiovascular Angiography and Intervention, SCD/Ventricular Arrhythmias, Acute Heart Failure, Interventions and ACS, Interventions and Imaging, Angiography, Nuclear Imaging
Keywords: Acute Coronary Syndrome, Alanine Transaminase, Angiography, Arterial Pressure, Blood Pressure, Heart Failure, Hospital Mortality, Hydrogen-Ion Concentration, Hypotension, Lactates, Myocardial Infarction, Out-of-Hospital Cardiac Arrest, Perfusion, Severity of Illness Index, Shock, Cardiogenic, Treatment Outcome
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