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

TL;DR

This study shows that lower minimum mean arterial pressure in cardiac ICU patients is strongly linked to higher mortality rates.

Contribution

The study identifies a reverse J-shaped relationship between minMAP and mortality in cardiac ICU patients, highlighting severe hypotension as a critical risk marker.

Findings

Lower minMAP values were incrementally associated with higher in-hospital and 30-day mortality.

Patients with minMAP <37 mm Hg had the highest mortality risk, with adjusted odds and hazard ratios significantly elevated.

The association between minMAP and mortality was consistent across admission diagnoses and vasoactive drug use.

Abstract

Hypotension is associated with increased mortality in critical care settings; limited data exist on the minimum mean arterial pressure (minMAP) in cardiac critical illness.

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).

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.

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.

We observed a graded association between lower minMAP and increased mortality, re-emphasizing severe hypotension as a critical physiological marker of patient vulnerability.

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