The prognostic significance of early and late anaemia in acute coronary syndrome

Abstract

Anaemia in acute coronary syndrome (ACS) is a common and strong independent risk factor but it is unknown whether early anaemia is transient or whether it persists over the subsequent weeks. We also sought to evaluate whether late anaemia carries the similar prognostic significance as baseline anaemia. Another unknown is whether haemoglobin improves risk stratification over and above the GRACE score. Haemoglobin levels were prospectively measured in 448 consecutive patients presenting with ACS and at 7-weeks follow-up. Cardiovascular endpoints were defined as death or acute myocardial infarction (AMI) over a median duration of 30 months (range 1-50). The prevalence of anaemia on admission was 20% and this increased to 40% at 7-weeks follow-up. New anaemia occurred in 31% of patients. Baseline anaemia predicted CV endpoints independent of the admission GRACE (Global Registry of Acute Coronary Events) score [adjusted RR 2.54 (95% CI 1.73-3.71)]. Anaemia at 7-weeks follow-up was also a strong predictor of adverse outcomes [adjusted RR 1.67 (95% CI 1.04-2.69)]. Patients with persistent anaemia at 7 weeks were at an increased risk of death or AMI compared to those with persistently normal haemoglobin [unadjusted RR 3.58 (95% CI 2.04-6.29)]. In ACS, the prevalence of anaemia doubles from admission to 7-weeks follow-up (40%). Not only did baseline anaemia predict long-term prognosis independent of the admission GRACE score, but haemoglobin at 7-weeks post-ACS was also a simple independent predictor of adverse prognosis.