Cardiogenic shock classification evaluation after cardiac surgery to predict in-hospital mortality

Background The Society for Cardiovascular Angiography and Interventions (SCAI) classification is a risk stratification tool to define the severity of cardiogenic shock [1,2]. Earlier studies conducted in predominantly critically ill cardiac non-surgical patients have reported in-hospital mortality rates for each SCAI shock stage as follows: A, 1-5%; B, 0-34%; C, 11-54%; D, 24-68%; and E, 42-77% [3]. However, it is unknown whether the SCAI shock classification confers prognostic value in patients after cardiac surgery. Purpose To assess whether the SCAI shock stage classification is a prognostic tool for cardiac surgery patients postoperatively. Methods A single-center retrospective analysis was conducted in 9.293 cardiac surgery patients operated between 2015 and 2024. All patients were categorized into SCAI shock stages A through E, at 0-24 hours, 24-48 hours and up to 144-168 hours postoperatively. Absolute, maximum and changes in SCAI shock stage were tested. The relationship between SCAI shock stages and in-hospital mortality was evaluated. Results Distribution of patients across SCAI shock stages A to E during the first 0-24 hours postoperative was 42%, 18%, 5%, 33%, and 2%, with corresponding in-hospital mortality rates of 0.3%, 1%, 4%, 4%, and 35%(p<0.001; p<0.001). At 48-72 hours postoperatively the distribution and associated in-hospital mortality of patients differs, as seen in Figure 1. At 48 hours postoperatively, 91% of patients were classified as SCAI shock stage A or B(p<0.001). Only SCAI shock stage E was associated with high in-hospital mortality from baseline onwards. Among patients in non-resolving shock (i.e. those who did not improve, remained in shock or died) and resolving shock (i.e. those who improved or remained in no shock) between 0-24 hours and 48-72 hours postoperatively, the difference in distribution is seen at Figure 2. The in-hospital mortality rates associated with non-resolving shock after 48 hours were markedly higher — 13%, 19%, 42%, 22%, and 85% — compared to resolving shock, with mortality rates of 0.2%, 0.7%, 1.5%, 1.5%, and 15%(p<0.001). Kaplan-Meier analysis, corrected for Benjamini-Hochberg, showed no stepwise increase in in-hospital mortality across SCAI shock stages within 48 hours, but this became significant after 48 hours, except between stage A and B(p=0.114). However, when stages A and B were combined, mortality was significantly lower compared to stage C(p<0.001). Conclusion(s) The SCAI shock stage classification is not related to in-hospital mortality when evaluated during the first 48 postoperative hours except for patients in stage E for whom it is a strong indicator of high in-hospital mortality. After 48 hours the prognostic value of the SCAI shock stage classification improves for the different SCAI shock stages as it aligns more closely with the in-hospital mortality. This implies that in the first 48 postoperative hours other factors play a crucial role in determining patient outcomes.Shock stage distribution and mortality Non-resolving and resolving shock