Ability of a novel shock index that incorporates invasive hemodynamics to predict mortality in patients with ST‐elevation myocardial infarction

Abstract

Objective: To determine whether the use of invasively measured hemodynamics improves the prognostic ability of a shock index (SI).Background: SI such as Admission-SI, Age-SI, Modified SI (MSI), and Age-MSI predict short-term mortality in ST-elevation myocardial infarction (STEMI).Methods: Single-center study of 510 patients who underwent primary percutaneous coronary intervention. STEMI SI was defined as age × heart rate (HR) divided by coronary perfusion pressure (CPP). Results:The mean age was 62 ± 14 years, 66% were males with hypertension (69%), tobacco use (38%), diabetes (28%) and chronic kidney disease (6%). The mean HR, systolic blood pressure (SBP), and CPP were 81 ± 18 bpm, 124 ± 28 mmHg, and 52.8 ± 16.3 mmHg, respectively. Patients with STEMI SI ≥182 (n = 51) were more likely to experience a cardiac arrest in the catheterization laboratory (9.8% vs. 2.0%; p = .001), require mechanical circulatory support (47.1% vs. 8.5%; p < .0001) and be treated with vasopressors (56.9% vs. 10.7%; p < .0001) compared to STEMI SI < 182 (n = 459). After multivariate adjustment, patients with STEMI SI ≥182 were 10, 10.1 and 4.8 times more likely to die during hospitalization, at 30 days and at 5 years, respectively. The C statistic of STEMI SI was 0.870, similar to GRACE score (AUC = 0.902; p = .29) and TIMI STEMI score (AUC = 0.895; p = .36).Conclusion: STEMI SI is an easy to calculate risk score that identifies STEMI patients at high risk of in-hospital death.

Shock indices in acute myocardial infarction

“…In conclusion, although the STEMI Shock Index was not clearly superior to existing tools for prediction of mortality in acute myocardial infarction, McKenzie et al 5 have highlighted a vital need to facilitate early identification of cardiogenic shock complicating acute myocardial infarction and an opportunity to incorporate hemodynamic parameters to refine its diagnosis and management.…”

“…In this issue of the Journal, McKenzie et al 5 describe the utility of a novel index combining noninvasive and invasive hemodynamic parameters to predict mortality after STEMI. Their STEMI Shock Index ([heart rate × age]/[diastolic blood pressure − LVEDP]) is built upon existing shock indices to incorporate coronary perfusion pressure.…”

“…In this issue of the Journal, McKenzie et al 5 Given the infrequency of in-hospital mortality after STEMI in contemporary practice, the study was rather underpowered to discern subtle differences in predictive ability among different, related indices.…”