Prognostic value of serum immunoglobulin M levels in patients with acute coronary syndrome

Background and aims The immuno-inflammatory response is a crucial early step in the development of acute coronary syndrome (ACS). In this study, we investigated whether immunoglobulin M (IgM) in the body's initial immune response can predict the prognosis of patients with ACS. Methods This prospective cohort study enrolled 1556 ACS patients at Beijing Hospital between March 2017 and October 2020. All patients underwent coronary angiography (CAG). The serum IgM concentration and biochemical indicators were evaluated prior to CAG. The primary endpoint was the composite endpoint of major adverse cardiovascular and cerebrovascular events (MACCEs). Multivariate Cox proportional hazards models was used to explore the association between IgM levels and the endpoint. Results The average serum IgM levels of the population was 61.3 (42.6 - 88.4) mg/dL. During the median follow-up period of 55 months, 150 MACCEs occurred. Kaplan-Meier analysis showed that low serum IgM levels were associated with occurrence of MACCEs (log-rank p = 0.009). Univariate Cox proportional hazards models showed that low serum IgM ( ≤ 78.05mg/dL) was associated with MACCEs (hazard ratio (HR) 1.648, 95% confidence interval (CI): 1.129-2.406, p = 0.010). In patients with IgM ≤ 78.05mg/dL, the HR for partially adjusted MACCEs events was 1.576 (95% CI: 1.075-2.310) and 1.930 (95% CI: 1.080-3.449) after adjusting for multiple covariates. The subgroup analysis showed that for patients in ≤ 24 BMI, never smoking and non-dyslipidemia subgroup, the lower serum IgM levels was significantly associated with the risk of MACCEs (pinteraction < 0.001, pinteraction = 0.037, pinteraction = 0.024, respectively). Conclusions Low serum IgM levels was independently associated with MACCEs in ACS patients, especially for patients without obesity, smoking and dyslipidemia.