Association between mild renal insufficiency, inflammatory status on initial admission, and 1-year mortality following ST-segment elevation myocardial infarction

The systemic inflammation tends to increase progressively as kidney function deteriorates. However, it remains unknown whether mild renal insufficiency affects inflammatory response at admission and subsequent clinical outcomes following ST-segment elevation myocardial infarction (STEMI). This study aimed to evaluate the joint, interactive, and mediating effects of estimated glomerular filtration rate (eGFR) and neutrophil-lymphocyte ratio (NLR) at admission on 1-year mortality in STEMI patients. Data were collected from 5,594 consecutive STEMI patients at seven centers (NCT04996901). Mildly reduced eGFR (60-89 mL/min/1.73m²) was associated with both elevated NLR and increased 1-year mortality (β 0.55, 95%CI [0.07-1.02], P = 0.024; HR 2.18, 95%CI [1.55-3.08], P < 0.001; respectively). Inflammation at admission mediated a small but significant proportion of the association between mildly reduced eGFR and mortality risk (1.7%, P = 0.030). Incorporating eGFR and NLR into a predictive model significantly improved mortality prediction following STEMI compared with clinical risk factors alone (C-index, 0.799 vs. 0.730, P < 0.001; net reclassification index 0.334, P < 0.001). These findings support the identification of patients at risk who may benefit from intensive kidney function monitoring and early adjuvant intervention, while also highlighting the need for developing anti-inflammatory therapies for STEMI patients with renal insufficiency.