Prognostic value of lactate in patients with cardiogenic shock with and without cardiac arrest.

Background: Arterial lactate on admission is a well-established marker of shock severity and prognosis in infarct-related cardiogenic shock (CS). However, it remains unclear whether its prognostic value differs between patients with and without pre-hospital cardiac arrest (CA).

Methods: We performed a pooled analysis of three randomized clinical trials on CS (IABP-SHOCK II, CULPRIT-SHOCK, and ECLS-SHOCK). Patients were stratified based on the presence or absence of pre-hospital CA. Admission arterial lactate levels were categorized into tertiles: < 3.6, 3.6-7.1, and > 7.1 mmol/L. The primary endpoint was 1-year all-cause mortality.

Results: A total of 1401 patients (804 with CA and 597 without CA) were included. Higher admission lactate levels were associated with a linear increase in 1-year mortality. The prognostic performance of arterial lactate, assessed by the area under the curve (AUC), was 0.65 (95% CI 0.63-0.67). Patients with CA were more frequently represented in the highest lactate tertile compared to those without CA (31.6% vs. 8.8%). Across all tertiles, lactate levels were significantly associated with 1-year mortality, irrespective of CA status: 39.8% vs. 41.4% in the lowest tertile (p = 0.73), 48.6% vs. 50.8% in the intermediate tertile (p = 0.61), and 66.7% vs. 81.8% in the highest tertile (p = 0.0023), for CA and no-CA patients, respectively.

Conclusions: Admission arterial lactate is associated with 1-year mortality in infarct-related CS, regardless of pre-hospital CA. Although patients without CA generally had lower lactate levels, those in the highest lactate tertile experienced the highest mortality risk.