Abstract 12052: Association Between the Shock Index on Admission and In-Hospital Mortality in the Cardiac Intensive Care Unit

Introduction: An elevated shock index (SI) predicts worse outcomes in multiple clinical arenas. We aimed to determine whether the SI can aid in mortality risk stratification in unselected CICU patients.

Methods: We included admissions to the Mayo Clinic from 2007 to 2015 and stratified them based on admission SI, defined as heart rate divided by systolic blood pressure. The primary outcome was in-hospital mortality, and predictors of in-hospital mortality were analyzed using multivariable logistic regression.

Results: We included 9,939 unique CICU patients with available data for SI. The mean age was 69 years old (37% female). Median HR, SBP, and shock index for our cohort were 79 beats per minute (BPM), 121 mmHg, and 0.65 BPM/mmHg, respectively. Patients were grouped by SI as follows: < 0.6, 3,973 (40%); 0.6-0.99, 4,810 (48%); and ≥ 1.0, 1,156 (12%). After multivariable adjustment, both HR (adjusted OR 1.06 per 10 BPM higher; CI 1.02-1.10; p-value 0.005) and SBP (adjusted OR 0.94 per 10 mmHg higher; CI 0.90-0.97; p-value < 0.001) remained associated with higher in-hospital mortality. As SI increased there was an incremental increase in in-hospital mortality (adjusted OR 1.07 per 0.1 BPM/mmHg higher, CI 1.04-1.10, p-Value < 0.001). A higher SI was associated with increased mortality across all examined admission diagnoses, including acute coronary syndromes, heart failure, and cardiogenic shock.

Conclusions: The SI is a simple and universally available bedside marker that can be used at the time of admission to predict in-hospital mortality in CICU patients across a variety of cardiac conditions.