Systemic Inflammatory Response Syndrome Is Associated With Increased Mortality Across the Spectrum of Shock Severity in Cardiac Intensive Care Patients

Abstract

Background: The systemic inflammatory response syndrome (SIRS) frequently occurs in patients with cardiogenic shock and may aggravate shock severity and organ failure. We sought to determine the association of SIRS with illness severity and survival across the spectrum of shock severity in cardiac intensive care unit (CICU) patients. Methods: We retrospectively analyzed 8995 unique patients admitted to the Mayo Clinic CICU between 2007 and 2015. Patients with ≥2/4 SIRS criteria based on admission laboratory and vital sign data were considered to have SIRS. Patients were stratified by the 2019 Society for Cardiovascular Angiography and Interventions (SCAI) shock stages using admission data. The association between SIRS and mortality was evaluated across SCAI shock stage using logistic regression and Cox proportional-hazards models for hospital and 1-year mortality, respectively. Results: The study population had a mean age of 67.5±15.2 years, including 37.2% women. SIRS was present in 33.9% of patients upon CICU admission and was more prevalent in advanced SCAI shock stages. Patients with SIRS had higher illness severity, worse shock, and more organ failure, with an increased risk of mortality during hospitalization (16.8% versus 3.8%; adjusted odds ratio, 2.1 [95% CI, 1.7–2.5]; P <0.001) and at 1 year (adjusted hazard ratio, 1.4 [95% CI, 1.3–1.6]; P <0.001). After multivariable adjustment, SIRS was associated with higher hospital and 1-year mortality among patients in SCAI shock stages A through D (all P <0.01) but not SCAI shock stage E. Conclusions: One-third of CICU patients meet clinical criteria for SIRS at the time of admission, and these patients have higher illness severity and worse outcomes across the spectrum of SCAI shock stages. The presence of SIRS identified CICU patients at increased risk of short-term and long-term mortality. Further study is needed to determine whether systemic inflammation truly drives SIRS in this population and whether patients with SIRS respond differently to supportive therapies for shock.