Introduction The risk stratification of haemodynamically stable patients presenting with pulmonary embolism (PE) is currently focussed on evidence of right ventricular (RV) dysfunction and myocardial necrosis (elevated Troponin). However these single markers have insufficient evidence to definitively guide treatment decision making. Plasma lactate has been shown to be potentially useful in identifying normotensive PE patients at high risk of PE related adverse events. The aim of this retrospective cross sectional study is to assess the role of serum lactate in the risk assessment of patients presenting with acute PE in a “real world” setting.

Methods We reviewed the cases of all patients with a radiologically confirmed PE on CTPA from Royal Wolverhampton Hospital between June 2014 and June 2015. The primary outcome was PE related complications within 7 days of diagnosis. This comprised of shock (systolic blood pressure <90 mmHg or pressure drop of ≥40 mmHg for ≥15 min), RV dysfunction, or need for cardiopulmonary resuscitation/mechanical ventilation.

Results 172 patients were diagnosed with acute PE during this time. 169 cases were analysed (insufficient information recorded in 3). Serum lactate was recorded in 92 (54.4%). Out of the 92 patients, 38 (41.3%) had a PE related complication with a higher average lactate (2.40 mmol/L) than the 54 (58.7%) who did not (lactate of 1.73 mmol/L) (p < 0.018 using the unpaired t test). PE related complications occurred in 33 (38.8%) of the 85 normotensive patients that had a lactate recorded. These patients also had a higher average lactate (2.24 mmol/L) than the 52 (61.2%) patients without complications (lactate 1.72 mmol/L) (p < 0.05). The positive predictive value of lactate as a single marker for a PE related complication is 53.1%. However the combination of a lactate ≥2, evidence of RV dysfunction and positive Troponin had a positive predictive value of 100%.

Conclusions This study adds to the evidence that a high serum lactate used in combination with a positive troponin and RV dysfunction can be a useful predictor of early adverse PE related events and may aid treatment decision making.