Background: Baseline arterial lactate levels and lactate clearance are well-established markers of shock severity and prognosis in patients with infarct-related cardiogenic shock (AMI-CS). In this substudy of the ECLS-SHOCK trial we investigated the prognostic value of these two parameters in patients with and without extracorporeal life support (ECLS) therapy and investigated their influence on the effect of ECLS therapy.
Methods: Of the 420 patients enrolled in the ECLS-SHOCK trial, 412 patients with available arterial lactate values at baseline (n=207 in ECLS group, n=205 in control group) were included and divided into tertiles (< 5.3, 5.3-8.6,> 8.6 mmol/L). For the analysis of lactate clearance 370 patients (n=186 in ECLS group, n=184 in control group) with available lactate values also 8 hours after percutaneous coronary intervention (PCI) were included and divided into tertiles (< 3.5, 3.5-7.3, > 7.3-18.3mmol/L). The primary endpoint was 30-day all-cause mortality.
Results: Higher baseline lactate levels were associated with higher 30-day mortality in both groups (ECLS group: tertile 3 vs. tertile 1 relative risk (RR) 2.03 [95 % confidence interval (CI) 1.36-3.05], tertile 2 vs. tertile 1 RR 1.71 [95 % CI 1.13-2.59]; control group: tertile 3 vs. tertile 1 RR 2.82 [95 % CI 1.79-4.44], tertile 2 vs. 1 RR 2.03 [95 %CI 1.24-3.33]) (Figure 1). Furthermore, lower lactate clearance was associated with higher 30-day mortality (ECLS group: tertile 1 vs. tertile 3 RR 2.86 [95 % CI 1.64-5.00], tertile 2 vs. tertile 3 RR 2.10 [95 % CI 1.16-3.80]); control group: tertile 1 vs. tertile 3 RR 2.23 [95 % CI 1.51-3.31], tertile 2 vs. tertile 3 RR 1.27 [95 % CI 0.80-2.02]) (Figure 2). No significant benefit of ECLS therapy in comparison to medical therapy alone could be observed in any of the subgroups (Figure 3).
Conclusion: Arterial lactate levels at baseline and lactate clearance were significantly associated with 30-day mortality in AMI-CS patients receiving ECLS therapy and in patients receiving medical therapy alone. However, the efficacy of ECLS treatment was neither affected by baseline lactate values nor by lactate clearance.
