Lactate Clearance – A surrogate for Mortality in Cardiogenic Shock

Abstract

Raised blood lactate levels are strongly associated with mortality in patients with cardiogenic shock. Recent practices of the early identification and initiation of mechanical circulatory support have improved outcomes in cardiogenic shock, but therapeutic targets to guide real-time clinical decision making are lacking. Recent evidence suggests that the degree and rate at which blood lactate levels decrease after the initiation of treatment is important in patient prognosis. With this background, lactate clearance has been suggested as a potential treatment target due to its independent association with morality. Lactate levels were measured at baseline and at 6, 12, and 24 h. Patients were grouped into survivors and non-survivors based on in-hospital mortality. Patients who had normal lactate (<2.0 mmoL/L) at baseline were excluded from the study. Statistical analysis done using appropriate tests. Absolute lactate levels were compared between groups at baseline and 6, 12, and 24 h. Lactate clearance was calculated at 6, 12, and 24 h among survivors and non-survivors. In total, 90 patients were enrolled, and 65 (72.2%) of them survived to hospital discharge. Absolute blood lactate levels were 4.71 ± 1.36 mmoL/lit in survivors and 6.17 ± 2.88 mmoL/lit in non-survivors at baseline (P = 0.007). The mean lactate clearance at 6 h was 12.22 ± 85.96% in survivors and 12.98 ± 30.97% in non-survivors (P = 0.3). At 24 h, the mean lactate clearance was 54.63 ± 22.34% and 26.34 ± 19.3% in survivors and non-survivors, respectively (P < 0.01). Survivors had significantly greater lactate clearance at 12 and 24 h compared with non-survivors, suggesting that lactate clearance is an important prognostic marker in cardiogenic shock. These results further support the validity of lactate clearance as an appropriate surrogate for mortality and as a potential therapeutic target in clinical practice. Especially in centers lacking invasive hemodynamic monitoring.