Ethnic variations in neutrophil count as predictors of prognosis following acute myocardial infarction

Abstract

Aims

Elevated neutrophils are associated with a poor prognosis after acute myocardial infarction (AMI) but it is not known if ethnicity influences the association between neutrophil count and outcome. We aimed to describe the temporal dynamics of neutrophils after AMI, and assess the interaction between ethnicity, neutrophil count, and outcomes after AMI.

Methods

Consecutive patients presenting with AMI between 2016 and 2023 were divided into two groups according to their median neutrophil count. Ethnicity was dichotomised as white and other ethnic groups combined (referred to as ‘ethnic minorities’). The primary outcome was in-hospital mortality, with a secondary outcome of 60-day mortality.

Results

In our study of 3062 AMI patients (76 % white, 24 % from ethnic minority groups), we found that neutrophil counts rose early post AMI, which coincided with a nadir of the other cell groups. We identified a relative baseline neutropenia in ethnic minority individuals, compared to white individuals (6.85 vs 8.42 × 10⁹/L). We observed a significant, independent association between elevated neutrophils at baseline and the primary outcome of in-hospital mortality (OR 2.06, p < 0.001) and secondary outcome of 60-day all-cause mortality (HR 1.08, p = 0.002). Sub-group analysis revealed a significant interaction between ethnicity and elevated neutrophils (p = 0.004), indicating that a comparable neutrophil count conferred an increased risk for ethnic minority patients for both outcomes.

Conclusions

We report ethnicity-specific leucocyte dynamics after AMI. Furthermore, neutrophil count is associated with a disproportionate risk in ethnic minority compared with white individuals. Understanding post-AMI inflammation and its interaction with ethnicity is essential in providing personalised prognostication and patient management.