[Hemoglobin: simply a laboratory value or a powerful predictor of risk in patients with acute coronary syndrome?].

INTRODUCTION: Anemia has been shown to be associated with a worse prognosis, especially higher mortality in various pathological conditions. However, few studies have specifically examined its impact in acute coronary syndrome (ACS) patients. The purpose of our study was to assess the association between different quartiles of hemoglobin on admission and short- and long-term prognosis in patients with ACS.

METHODS: We performed a retrospective analysis of 1303 consecutive ACS patients admitted to a coronary care unit and analyzed the association between baseline hemoglobin and morbidity and mortality, in-hospital and at 12-month follow-up. The population was divided into groups according to quartiles of hemoglobin concentration (Hb): Q1: <10.8g/dl; Q2: 10.8-12.2g/dl; Q3: 12.3-13.2g/dl; Q4: ≥13.3g/dl. Logistic regression analysis was used to identify independent predictors of short- and long-term mortality.

RESULTS: Hypertension and diabetes mellitus were more common in the lower Hb quartiles, while the prevalence of smoking and physical inactivity increased with higher Hb. A higher proportion of patients in the lower quartiles had congestive heart failure, peripheral artery disease and previous stroke or transient ischemic attack. Anemic patients tended to be older, with worse renal function and left ventricular systolic function. Patients in Q1 had significantly higher levels of troponin I and blood glucose on admission. Anemic patients showed significantly higher in-hospital mortality (Q1: 9.8%; Q2: 6.3%; Q3: 4.1%; Q4: 3.6%, p<0.001), longer hospital stay (Q1: 6.1±4.4; Q2: 5.2±3.0; Q3: 4.9±2.7; Q4 4.3±2.1 days, p<0.001) and higher 1-year mortality (Q1: 23.6%; Q2: 11.6%; Q3: 10.6%; Q4: 5.5%, p<0.001). In multivariate analysis, the only independent predictor of in-hospital mortality was Killip class >1 at admission. The independent predictors of long-term mortality were age ≥69.5 years, Killip class >1 at admission, diabetes mellitus, ST-segment depression on admission ECG and Hb <10.8g/dl.

DISCUSSION AND CONCLUSIONS: Low baseline hemoglobin is associated with more comorbidities and can accurately predict 1-year mortality after an acute coronary syndrome.