The Hidden Burden of Depression in STEMI: Effects on Early Complications and 12-Month MACCE.

Background/Objectives: Depression is a frequent but underrecognized comorbidity in ST-segment elevation myocardial infarction (STEMI) and is associated with adverse cardiovascular outcomes. The interplay between pre-existing depression, systemic inflammation, and major adverse cardiovascular and cerebrovascular events (MACCE) in STEMI remains insufficiently explored. This study aimed to investigate this interplay in a cohort of patients with STEMI. Methods: This retrospective observational cohort study included 292 consecutive patients with STEMI admitted between September 2023 and September 2024. Depression was identified through pre-existing psychiatric diagnoses. Inflammatory markers (C-reactive protein (CRP), neutrophil-to-lymphocyte ratio (NLR), systemic immune-inflammation index (SII)) and echocardiographic parameters, including left ventricular ejection fraction (LVEF), were collected at baseline and 12-month follow-up. In-hospital and 12-month MACCE were defined as composite endpoints. Results: Depression was present in 21.2% of patients. Patients with depression exhibited significantly higher CRP, NLR, SII, 48-h troponin levels, no-reflow incidence, and longer hospitalization. In-hospital MACCE occurred in 24.2% versus 11.7% of patients (p = 0.014), driven mainly by recurrent myocardial infarction, with a trend toward severe heart failure. At 12 months, MACCE occurred in 53.22% of patients with depression versus 23.5% of patients without (p < 0.001). Independent predictors of 12-month MACCE included depression (OR 3.35), baseline SII (OR 4.89 per 1000 units), baseline CRP (OR 1.48 per 10 mg/L), and 12-month LVEF (OR 0.69 per 5% increase). No significant interaction was observed between depression and inflammatory or functional parameters. Conclusions: Pre-existing depression was independently associated with increased in-hospital and 12-month MACCE risk in patients with STEMI. Future prospective studies should assess whether treating depression improves long-term STEMI outcomes.