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

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.