Background: Cardiogenic shock complicating acute myocardial infarction is associated with a high mortality rate. Cardiogenic shock after out-of-hospital cardiac arrest (OHCA) can be due to transient myocardial stunning but also reflect the increasing severity of ongoing heart failure. The Society for Cardiovascular Angiography and Interventions (SCAI) proposed a division of cardiogenic shock into 5 phenotypes, with cardiac arrest being a modifier. The objective was to apply SCAI shock classification to a well-characterized OHCA population and describe the hemodynamic characteristics and prognostic significance of increasing SCAI classes.
Methods and results: This is a post hoc analysis of data from the BOX (Blood Pressure and Oxygenation Targets in Post Resuscitation Care) trial of comatose patients with OHCA. Patients were classified according to SCAI class upon hospital admission. Invasive arterial and pulmonary arterial measurements were obtained the first 72 hours after admission, and perfusion pressure, cardiac index and cardiac power output were calculated. Of 789 patients included, 31.6% were classified as SCAI class B/C, 29.9% as SCAI class D, and 38.5% as SCAI class E. The first recorded perfusion pressure differed between SCAI class B/C, D, and E being lower in higher SCAI classes. The difference was found only at the first measurement. Cardiac index and cardiac power output did not differ at any time point between classes. The 1-year mortality rate increased with SCAI Class B/C to E (21.3%, 34.3%, and 48.4%, respectively; P<0.001).
Conclusions: The 1-year mortality rate after OHCA increased with increasing SCAI classes, but cardiac index, cardiac power output, and perfusion pressure remained notably similar in the first 72 hours after admission. This challenges whether all OHCAs should be recorded as SCAI class E by default.
Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT03141099.
Keywords: cardiogenic shock; death; hemodynamics; out‐of‐hospital cardiac arrest.