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

Abstract

Background Lactic acidosis is associated with mortality in patients with cardiogenic shock (CS). Elevated lactate levels and systemic acidemia (low blood pH) have both been proposed as drivers of death. We, therefore, analyzed the association of both high lactate concentrations and low blood pH with 30‐day mortality in patients with CS. Methods and Results This was a 2‐center historical cohort study of unselected patients with CS with available data for admission lactate level or blood pH. CS severity was graded using the Society for Cardiovascular Angiography and Intervention (SCAI) shock classification. All‐cause survival at 30 days was analyzed using Kaplan‐Meier curves and Cox proportional‐hazards analysis. There were 1814 patients with CS (mean age, 67.3 years; 68.5% men); 51.8% had myocardial infarction and 53.0% had cardiac arrest. The distribution of SCAI shock stages was B, 10.8%; C, 30.7%; D, 38.1%; and E, 18.7%. In both cohorts, higher lactate or lower pH predicted a higher risk of adjusted 30‐day mortality. Patients with a lactate ≥5 mmol/L or pH <7.2 were at increased risk of adjusted 30‐day mortality; patients with both lactate ≥5 mmol/L and pH <7.2 had the highest risk of adjusted 30‐day mortality. Patients in SCAI shock stages C, D, and E had higher 30‐day mortality in each SCAI shock stage if they had lactate ≥5 mmol/L or pH <7.2, particularly if they met both criteria. Conclusions Higher lactate and lower pH predict mortality in patients with cardiogenic shock beyond standard measures of shock severity. Severe lactic acidosis may serve as a risk modifier for the SCAI shock classification. Definitions of refractory or hemometabolic shock should include high lactate levels and low blood pH.

Long-Term Mortality in Patients Transferred by Emergency Medical Services: Prospective Cohort Study

“…Sepsis, cardiogenic shock, and metabolic ketoacidosis are some examples of causes of metabolic acidosis. 25,26 Severe acidemia can lead to cardiovascular collapse because of hydrogen ion binding to cellular proteins, impairing their functions, and it may be associated with mortality. 27 Moreover, the findings on the strong correlation of elevated lactate levels and long-term mortality are consistent with other studies.…”

Advances in the Management of Cardiogenic Shock

“…As many as 30-50% of patients with CS have concomitant cardiac arrest (CA), which is associated with myocardial dysfunction, global ischemia-reperfusion injury, systemic inflammation, and higher mortality (5,22,(28)(29)(30). The end stage of CS characterized by severe lactic acidosis and multiple organ failure has been recently termed "hemometabolic" or "cardiometabolic" shock and is associated with RV congestion, greater shock severity, and worse outcomes (4,19,(31)(32)(33).…”

The changing face of cardiogenic shock: definitions, epidemiology, and severity assessment

“…Markers of tissue hypoperfusion, particularly the serum lactate level, are well recognized prognostic markers in patients with all forms of shock [23]. Accordingly, an elevated serum lactate level has consistently been identified as one of the most important predictors of higher mortality in patients with CS [26,28,33–39]. The association between a higher admission serum lactate level and increased mortality appears continuous without a clear threshold effect, but cut-offs ≥ 4–5 mmol/l are generally associated with worse outcomes and patients with a lactate ≥10 mmol/l have particularly poor outcomes [25,28,33,34,36,38].…”

“…Most importantly, there remains an important distinction between the severity of CS and mortality risk itself [22 ▪ ,23]. Although it is a truism that more severe CS will have a worse prognosis, there are numerous crucial risk factors for mortality that extend beyond shock severity alone [21 ▪▪ ,23,38]. Examples of nonmodifiable risk factors for mortality that are independent from shock severity itself include age and the presence of cardiac arrest with coma and anoxic brain injury [21 ▪▪ ,22 ▪ ,28,47–49].…”

“…Accordingly, an elevated serum lactate level has consistently been identified as one of the most important predictors of higher mortality in patients with CS [26,28,33–39]. The association between a higher admission serum lactate level and increased mortality appears continuous without a clear threshold effect, but cut-offs ≥ 4–5 mmol/l are generally associated with worse outcomes and patients with a lactate ≥10 mmol/l have particularly poor outcomes [25,28,33,34,36,38]. Perhaps more important than a single lactate measurement is the trend in lactate levels over time – failure of the expected decrease in lactate during hemodynamic support has a worse prognosis, particularly if lactate rises despite therapy [40].…”