Arterial Lactate in Cardiogenic Shock: Prognostic Value of Clearance Versus Single Values.

Objectives: This study sought to compare single lactate values at admission (L1) and after 8 h (L2) with lactate clearance (LC) for mortality prediction in cardiogenic shock (CS).

Background: Early estimation of prognosis in CS complicating acute myocardial infarction is crucial for tailored treatment selection. Arterial lactate is the most widely used point-of-care parameter in CS. In septic shock, lactate reduction over time-LC-has been extensively investigated. However, in CS, only limited data exist, and the prognostic value of LC is unknown.

Methods: This study is a subanalysis of the IABP-SHOCK II (Intraaortic Balloon Pump in Cardiogenic Shock II) trial and the corresponding registry. Lactate levels were prospectively collected. All-cause mortality at 30 days was assessed as primary endpoint.

Results: For 671 of 783 (85.7%) patients, L1 and L2 values were available. The area under the receiver-operating characteristic curve (L1: 0.69; L2: 0.76; LC: 0.59) showed no difference between L1 and LC (p = 0.20). In contrast, L2 was a significantly better predictive parameter than L1 or LC (p < 0.001 for both). In multivariable stepwise Cox regression analysis, L2 ≥3.1 mmol/l (best cutoff value by Youden index) and LC <-3.45%/h remained independently predictive for time to death (p < 0.001 for both), with L2 showing the highest chi-square test score (42.1) and hazard ratio (2.89; 95% confidence interval: 2.10 to 3.97).

Conclusions: Arterial lactate after 8 h is superior in mortality prediction in comparison with baseline lactate and LC. A cutoff value of 3.1 mmol/l for lactate after 8 h showed the best discrimination for assessing early prognosis in CS and may serve as new treatment goal. (Intraaortic Balloon Pump in Cardiogenic Shock II [IABP-SHOCK II]; NCT00491036).