Background: Cardiac arrest (CA) frequently coincides with cardiogenic shock (CS), significantly worsening neurologic prognosis and survival. However, as CA’s impact on outcome in CS likely varies depending on CA-specific characteristics, we aimed to identify the most relevant characteristics to determine neurologic prognosis and survival.

Methods: CS patients with or without CA treated at a tertiary care centre between 2009 and 2019 were retrospectively analyzed. Using adjusted regression models, different CA-specific characteristics were examined regarding their association with 30-day-mortality and hypoxic brain damage (HBD).

Results: CA occurred in 58% of 1312 included CS patients. CA was associated with higher mortality [hazard ratio (HR) 1.09, 95% confidence interval (CI) 0.88-1.36] and more HBD [odds ratio (OR) 9.03, 95%CI 5.39-15.12] than CS without CA. Among patients with CS and CA, only witnessed CA was associated with both, mortality (HR 0.64, 95%CI 0.44-0,91) and HBD (OR 0.41, 95%CI 0.23-0.75). In addition, an out-of-hospital-CA (OR 2.78, 95%CI 1.68-4.74) was associated with HBD, but not with mortality; and the presence of a shockable rhythm (HR 0.55, 95%CI 0.37-0.66) and the duration of CPR per 10 minutes (HR 1.11, 95%CI 1.07-1.14) were only associated with mortality, but not with HBD. There was no association between use of mechanical resuscitation devices and mortality/HBD (Figure 1).

Conclusion: Coinciding CA is a main driver of an impaired prognosis in CS, although the associated risk varies based on the presence of CA-specific characteristics. This could not only impact clinical practice, but might also be relevant to define CA-specific enrollment criteria in randomized trials.

Figure 1: Impact of CA-specific characteristics on outcome.