Association between low-dose aspirin therapy and major adverse cardiovascular events in ACS patients: A retrospective cohort study from the MIMIC-IV database

Acute coronary syndrome (ACS) remains a leading cause of morbidity and mortality worldwide. Low-dose aspirin therapy is a cornerstone treatment for secondary prevention in ACS patients, but the optimal dosing and its association with outcomes in specific high-risk subgroups remain incompletely defined.To assess the relationship between low-dose aspirin therapy and major adverse cardiovascular events (MACE), as well as its impact on bleeding risk in ACS patients, particularly those with diabetes mellitus (DM). We conducted a retrospective cohort study using the MIMIC-IV database, including 3,864 ACS patients. Aspirin use was determined from medication records, and doses were categorized as low (≤100 mg) or high (>100 mg). MACE was defined as a composite of cardiovascular death, recurrent myocardial infarction, or stroke within 1 year. Logistic regression and spline models were used to analyze the association between aspirin use and outcomes. Higher aspirin doses were independently associated with increased MACE risk (OR 1.37, 95% CI: 1.15-1.63, P<0.001). A J-shaped relationship was observed, with MACE risk rising sharply when aspirin doses exceeded 100 mg daily. Low-dose aspirin was associated with optimal MACE reduction (OR 0.75, 95% CI: 0.64-0.88, P<0.001) compared to no aspirin use. Aspirin was also a predictor of bleeding events (P<0.001). Subgroup analysis revealed a stronger protective aspirin-MACE association in diabetic patients on optimal glucose-lowering therapy. Low-dose aspirin therapy (≤100 mg daily) is associated with reduced MACE risk in ACS patients, while higher doses show diminishing cardiovascular benefits and increased bleeding risk. The optimal balance between efficacy and safety appears to occur at 81-100 mg daily, especially in diabetic patients with good glycemic control.