Prognostic value of plasma lactate levels among patients with acute pulmonary embolism: the thrombo-embolism lactate outcome study.

Study Objective: We investigate the prognostic value of plasma lactate levels in patients with acute pulmonary embolism.

Methods: We studied adult patients with symptomatic, objectively confirmed pulmonary embolism presenting to a single emergency department. Plasma lactate and troponin I levels were tested at presentation. We considered lactate values greater than or equal to 2 mmol/L and troponin I values greater than or equal to 0.10 ng/mL to be abnormal. Right-sided ventricular dysfunction was assessed by echocardiography. Primary endpoint was all-cause death occurring on or before 30 days after presentation. Secondary endpoints were the composite of all-cause death and clinical deterioration (defined as progression to shock, mechanical ventilation, or cardiopulmonary resuscitation) and death caused by pulmonary embolism. We tested the association between lactate level greater than or equal to 2 mmol/L and the endpoints using Cox proportional hazards regression analysis.

Results: Of the 270 patients included in the study, the mean age was 73 years (SD 12.7 years) and 151 (55.9%) were women. Twelve patients (4.4%) showed shock or hypotension (shock or systolic arterial pressure <100 mm Hg) at presentation, 109 (40.4%) had right-sided ventricular dysfunction, 93 (34.4%) showed troponin I level greater than or equal to 0.10 ng/mL, and 81 (30%) showed lactate level greater than or equal to 2 mmol/L. Seventeen patients (6.3%) died, 12 (4.4%) because of pulmonary embolism, and 37 (13.7%) reached the composite endpoint. Patients with lactate level greater than or equal to 2 mmol/L showed higher mortality (17.3%; 95% confidence interval [CI] 11.9% to 20%) than patients with a lower level (1.6%; 95% CI 0.8% to 1.9%). Plasma lactate level was associated with all-cause death (hazard ratio 11.67; 95% CI 3.32 to 41.03) and the composite endpoint (hazard ratio 8.14; 95% CI 3.83 to 17.34) independent of shock or hypotension, right-sided ventricular dysfunction, or elevation of troponin I values.

Conclusion: Patients with pulmonary embolism and elevated plasma lactate level are at high risk of death and adverse outcome, independent of shock or hypotension, or right-sided ventricular dysfunction or injury markers.