Background In recent years there has been growing interest in the identification of novel biomarkers that may enable early exclusion of acute coronary syndromes (ACS) in the Emergency Department (ED). Soluble CD40 ligand (sCD40L) has been identified as a potential marker of coronary plaque destabilisation and platelet activation. We aimed to investigate the value of sCD40L measured at the time of ED presentation for enabling early diagnosis and exclusion of ACS.

Methods We recruited patients presenting to the ED with suspected cardiac chest pain within the previous 24 h. We measured sCD40L in plasma samples taken at the point of ED presentation. All patients had troponin T measured at least 12 h after symptom onset and were followed up for 6 months for adverse events (death, acute myocardial infarction (AMI) or the need for urgent revascularisation).

Results 706 patients were recruited to the study. sCD40L levels were significantly lower in smokers, in patients with hyperlipidaemia or prior coronary revascularisation and in patients taking statins, r angiotensin-converting enzyme or calcium blockers. There was no significant difference in sCD40L levels between patients with (median 33.8ng/ml, IQR 18.0–80.5) and without (36.3 ng/ml, IQR 14.2–94.3) AMI (p=0.92) or between patients who did (34.0 ng/ml, 14.2–94.3) and who did not (34.9, 18.2–80.4) develop adverse events (p=0.82). The area under the Receiver Operating Characteristic curve was 0.50 (95% CI 0.45 to 0.56) for AMI and 0.49 (0.44–0.55) for adverse events. There was no trend towards increasing incidence of either outcome with ascending quintiles of sCD40L.

Conclusions sCD40L is unhelpful in the ED diagnosis of ACS. Future work in this area should focus on other biomarkers.