Laboratory Markers of Acidosis and Mortality in Cardiogenic Shock: Developing a Definition of Hemometabolic Shock

Abstract

Background: Acidosis and higher lactate predict worse outcomes in cardiogenic shock (CS) patients. We sought to determine whether overall acidosis severity on admission predicted in-hospital mortality in CS patients. Methods: This retrospective descriptive analysis included CS patients admitted to a single academic tertiary cardiac intensive care unit from 2007 to 2015. Admission arterial pH, base excess, and anion gap values were used to generate a Composite Acidosis Score (range 0-5, with a score !2 defining Severe Acidosis). Adjusted in-hospital mortality was analyzed using multivariable logistic regression. Results: We included 1,065 patients with median age of 68.9 (59.0, 77.2) years (36.4% females). Concomitant diagnoses included cardiac arrest in 38.1% and acute coronary syndrome in 59.1%. Severe Acidosis was present in 35.2%, and these patients had worse shock and more organ failure. In-hospital mortality occurred in 34.1% and was higher among patients with Severe Acidosis (54.9% vs. 22.4%, adjusted odds ratio [OR] 2.01, 95% CI 1.43-2.83, P < 0.001). Increasing Composite Acidosis Score was associated with higher in-hospital mortality (adjusted OR 1.25 per point, 95% CI 1.11-1.40, P < 0.001). Severe Acidosis was associated with higher hospital mortality at every level of shock severity and organ failure (all P < 0.05). Admission lactate level had equivalent discrimination for inhospital mortality as the Composite Acidosis Score (0.69 vs. 0.66; P ¼ 0.32 by De Long test). Conclusion: Given its incremental association with higher in-hospital mortality among CS patients beyond shock severity and organ failure, we propose Severe Acidosis as a marker of hemometabolic shock. Lactate levels performed as well as a composite measure of acidosis for predicting mortality.

Association Between the Acidemia, Lactic Acidosis, and Shock Severity With Outcomes in Patients With Cardiogenic Shock

“…Cardiogenic shock (CS) is associated with poor survival despite optimal contemporary therapy. 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 CS exists on a spectrum of severity, with a greater degree of hemodynamic compromise correlating to worse outcomes. 1 , 10 The degree of hemodynamic compromise during CS can be graded using the Society for Cardiovascular Angiography and Intervention (SCAI) shock classification.…”

“…Shock severity defined by the SCAI shock classification is associated with mortality in patients with CS and unselected patients treated in cardiac intensive care units. 6 , 7 , 8 , 9 , 10 , 11 , 12 Despite the potential to improve hemodynamics, an array of increasingly sophisticated percutaneous mechanical circulatory support devices have failed to improve survival in randomized trials. 13 , 14 , 15 , 16 Selection of appropriate patients, that is, those in whom the restoration of cardiac output will reverse CS, seems paramount to improve outcomes with mechanical circulatory support.…”

“…Noncardiovascular factors influence both prognosis and response to treatment in patients with CS, affecting the observed efficacy of tested therapies independent of shock severity. 5 , 6 , 8 During CS, tissue hypoperfusion and organ failure lead to metabolic deficiencies and a treatment‐resistant hemometabolic CS phenotype. 5 , 8 , 17 , 18 , 19 Simple blood biomarkers can capture this, as lactic acidosis (defined as an elevated blood lactate level) is a well‐established predictor of mortality in patients with CS.…”

“… 5 , 6 , 8 During CS, tissue hypoperfusion and organ failure lead to metabolic deficiencies and a treatment‐resistant hemometabolic CS phenotype. 5 , 8 , 17 , 18 , 19 Simple blood biomarkers can capture this, as lactic acidosis (defined as an elevated blood lactate level) is a well‐established predictor of mortality in patients with CS. 8 , 20 , 21 , 22 , 23 , 24 , 25 Likewise, systemic acidemia (defined as a low blood pH) predicts mortality in patients with CS and may quantify the severity of the hemometabolic disturbance.…”

Validation of cardiogenic shock phenotypes in a mixed cardiac intensive care unit population

“…This severely ill “hemometabolic” cluster had twofold higher in‐hospital mortality, even after adjustment for the severity of shock and overall critical illness. This emphasizes the importance of hemometabolic shock, defined by kidney and liver injury with metabolic acidosis, as a high‐risk phenotype of CS 7,14 . It is notable that substantial differences between the phenotypes exist regarding hemodynamics and echocardiographic variables despite clustering using a limited number of laboratory variables.…”