Mild haemoglobin drop and clinical outcomes in acute coronary syndrome patients: finding from the BleeMACS registry.

BACKGROUND: Haemoglobin drop is common in acute coronary syndrome (ACS) patients and correlates with poor prognosis. However, the association between mild haemoglobin drop and adverse clinical outcome remains insufficiently investigated. This study aimed to examine the association between in-hospital haemoglobin drop and risk for adverse clinical outcomes in ACS patients, especially those with mild drop. METHODS: Included patients from the BleeMACS (Bleeding complications in a Multicenter registry of patients discharged after an Acute Coronary Syndrome) registry were categorized into three groups by the presence and amount of in-hospital haemoglobin drop (non-drop, mild drop and severe drop). The cut-off point between mild drop and severe drop is ≥ 3 g/dL. Multivariate Cox regression was used to assess the association between haemoglobin drop and major adverse cardiac endpoints (MACE). Patients taking potent P2Y12 inhibitors were selected for the additional analysis. Propensity score matching was used to avoid selective bias in the additional analysis. RESULTS: Of 6911 patients, 4949 patients (71.6%) experienced in-hospital haemoglobin drop. Compare with non-drop group, patients with haemoglobin drop had higher risk of MACE [adjusted hazard ratio (HR) = 1.36, 95% CI: 1.03-1.80 for mild drop group; adjusted HR = 1.70, 95% CI: 1.07-2.68 for severe drop group]. Patients in mild drop group were less likely to receive potent P2Y12 inhibitors at discharge (mild drop group vs. severe drop group vs. non-drop group: 10.9% vs. 10.7% vs. 23.8%). After propensity score matching adjustment among patients with potent P2Y12 inhibitors, patients in mild drop group were not associated with an increased risk of MACE than those in non-drop group (adjusted HR = 1.52, 95% CI: 0.49-4.72). CONCLUSIONS: In-hospital haemoglobin drop was common in ACS patients and associated with a higher risk for adverse events. Reduced prescription for potent P2Y12 inhibitors may be responsible for poor prognoses among patients with mild haemoglobin drop.