Minimum Mean Arterial Pressure and Associated Mortality Outcomes in the Cardiac Intensive Care Unit

BACKGROUND: Hypotension is associated with increased mortality in critical care settings; limited data exist on the minimum mean arterial pressure (minMAP) in cardiac critical illness. OBJECTIVES: The objective of the study was to investigate the prognostic value of the minMAP within the first 24 hours of admission to cardiac intensive care unit (CICU). METHODS: This retrospective, single-center study included adult CICU patients (2007-2018). The minMAP within the first 24 hours was the exposure of interest. Patients were categorized into four minMAP groups using a classification and regression tree model. Primary outcome was in-hospital mortality; secondary, 30-day mortality. Multivariable logistic and Cox regression models were adjusted for confounders. RESULTS: Of 11,930 patients, the median minMAP was 54 (47, 62) mm Hg, distributed as follows: ≥57 (42.4%, n = 5,053); 48 to 57 (30.5%, n = 3,635); 37 to 48 (20.1%, n = 2,392); and <37 (7.1%, n = 850). In-hospital mortality was 9.1% (n = 1,080), and 11.7% (n = 1,364) died within 30-days of CICU admission (30-day mortality 11.7% [11.1% to 12.3%] by the Kaplan-Meier method). The lower minMAP was incrementally associated with higher mortality in a continuous, reverse J-shaped manner, with the lowest mortality at 71 to 75 mm Hg. Patients with minMAP <48 mm Hg had substantially higher in-hospital (adjusted OR: 1.60 [1.36-1.88]; P < 0.001) and 30-day (adjusted HR: 1.47 [1.31-1.65]; P < 0.001) mortality. The minMAP <37 mm Hg had the highest risk in-hospital (adjusted OR: 2.19 [1.67-2.86]; P < 0.001) and 30-day (adjusted HR: 1.95 [1.61-2.36], P < 0.001) mortality. Lower minMAP was associated with higher mortality across admission diagnoses and regardless of vasoactive drugs administration. CONCLUSIONS: We observed a graded association between lower minMAP and increased mortality, re-emphasizing severe hypotension as a critical physiological marker of patient vulnerability.