Cardiogenic shock: classification, characteristics and mortality

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Cardiogenic shock has high morbidity and mortality and has a very heterogeneous treatment. In 2019, the Society for Angiography and Cardiovascular Intervention proposed a classification to define the severity of shock, categorizing patients into 5 stages, from A to E. Since then, the association of these different stages with mortality seems to be better established.

However, shock is dynamic and patients can change from one stage to another. In addition, the physical examination parameters, laboratory and hemodynamic changes used to classify the patient are not uniform. Therefore, a better definition of these parameters is necessary, using information that is easily accessible and applicable, with clinical significance and that really makes a difference in practice.

A study was then carried out to refine the 2019 definitions. Data from patients in cardiogenic shock are documented and analyzed by a group called Cardiogenic Shock Working Group (CSWG) since 2016, with information from 17 centers in the US. From these data, clinical parameters related to hypotension and hypoperfusion were selected and validated, with the objective of defining specific intervals for each parameter used in the classification of stages of shock. In addition, data on the incidence and progression of shock were obtained in relation to the initial stage of admission and a correlation was made between in-hospital mortality and the initial and maximum stage of shock reached.

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Cardiogenic shock classification, characteristics and mortality

Study methods and population involved

The data obtained were as close as possible to admission and at specific times during hospitalization. For the diagnosis of shock, it was necessary to have at least one of the changes in a sustained manner: systolic BP (SBP) < 90 mmHg for at least 30 minutes, use of vasoactive drugs (VAD) to maintain SBP, cardiac index (CI) less than 2 .2 L/min/mtwo in the absence of hypovolemia or use of a mechanical ventricular assist device.

Between 2016 and 2020, data were obtained from 3,455 patients admitted with a diagnosis of cardiogenic shock. Specific parameters were selected to define the severity of shock: presence of out-of-hospital CRP, lactate level, TGP, SBP or mean BP (MAP) and pH. Each parameter was evaluated separately in relation to in-hospital mortality.

The shock stages were defined retrospectively according to the following parameters:

  • Stage B: isolated hypoperfusion (lactate 2-5 mmol/L or TGP 200-500 U/L) OR hypotension (SBP 60-90 mmHg or MAP 50-65 mmHg) without the use of VAD or devices.
  • Stage C: hypoperfusion AND hypotension, with the same criteria as stage B, or use of 1 VAD (vasopressor or inotrope) or 1 device.
  • Stage D: hypoperfusion (lactate 5-10 mmol/L or TGP > 500 U/L) AND hypotension (SBP 60-90 mmHg or MAP 50-65 mmHg), or use of 2 to 5 VADs or devices. This group also included patients with 1 VAD or 1 device with persistent hypotension and hypoperfusion despite treatment.
  • Stage E: hypotension (SBP < 60 mmHg or MAP < 50 mmHg) or hypoperfusion (lactate > 10 mmol/L or pH ≤ 7.2) or need for more than 3 ADV or 3 devices. This group also included all patients with out-of-hospital cardiac arrest.


Patients had a mean age of 62 years, 71% were male and 59% white. The cause of cardiogenic shock was acute myocardial infarction (AMI) in 32%, heart failure (HF) in 52% and other causes in 16%.

Compared to patients with HF, patients with AMI were older and had a higher prevalence of hypertension and diabetes, a lower prevalence of atrial fibrillation (AF), chronic kidney disease (CKD) and valvular heart disease. They also had higher left ventricular ejection fraction (LVEF), MAP, lactate and TGP and lower heart rate (HR), mean pulmonary artery pressure and creatinine levels.

Overall in-hospital mortality was 35%, being higher in patients with AMI compared to patients with HF (42% vs. 25%, p < 0.0001). Mortality was higher in patients who had out-of-hospital cardiac arrest, both in total and in groups with AMI and HF. Patients who died had more comorbidities, higher ventricular filling pressure and higher HR, lower MAP and lower pulmonary artery pulsatility index.

There was a direct association between in-hospital mortality and treatment intensity, ie, the greater the amount of VAD and devices, the greater the mortality (OR 2.304, 95%CI 2.13-2.49, p < 0.001). This occurred in both AMI and HF cases. Each parameter selected (SBP, MAP, lactate, TGP, pH) was associated with mortality and this association remained significant after multivariate analysis.

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Regarding the different stages of shock, most patients were initially in stage D (23%) or E (22.8%) and there was a significant association with mortality. In addition to the initial stage of shock, the worst stage reached at admission was also related to higher mortality. Patients with AMI in shock initially stages D and E and those who reached stages C, D and E on admission had higher mortality compared to those with HF.

As for the progression of shock over the course of hospitalization, 90% of patients who arrived in stage B changed to a worse category in an average of 52 hours, 68% of those in stage C worsened in an average of 103 minutes and 18% of those who arrived in stage D switched to stage E in an average of 178 hours. Worsening to stage E, regardless of the initial stage, was related to high mortality and progressing to this stage had higher mortality than reaching it. Patients with HF took longer to progress in stage compared to patients with AMI.

Comments and conclusion

This study brought interesting results:

  • The mortality of patients in cardiogenic shock was higher when the cause was AMI compared to HF and the baseline characteristics of these two groups of patients were different.
  • There was an association of mortality with the occurrence of out-of-hospital cardiac arrest, with treatment intensity and with each parameter of hypotension and hypoperfusion evaluated in isolation. In addition, these parameters were easily used to classify patients in different stages of shock and were able to help in the detection of patients in profile B without hypotension, which allows for earlier initiation of treatment.
  • Progression from the initial stage of shock to worse was common and the time for this progression varied depending on the initial stage and depending on the cause of shock, patients with HF took longer to progress to worsening than patients with AMI.

Despite being an observational and retrospective study, which does not allow for possible confounding factors to be excluded, these results showed a more objective classification of cardiogenic shock and different patient characteristics depending on its cause.

The definition of patterns of populations and evolution of shock can help in the creation of algorithms to improve the management of these patients and the parameters of definition of shock, now better defined, helped in the diagnosis, which allows earlier treatment and stabilization, helping in reducing the progression of shock, which would have a consequent reduction in mortality.


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