Abstract Body (Do not enter title and authors here): Background.
Naples prognostic score (NPS) is a recently developed tool for assessing inflammatory and nutritional status. It is commonly used to evaluate cancer patients.

Purpose.
We aimed to investigate the impact of NPS on clinical outcomes in ST-elevation myocardial infarction (STEMI) patients undergoing primary percutaneous coronary intervention (PPCI).

Methods.
We comprehensively searched PubMed, WOS, SCOPUS, EMBASE, and CENTRAL through June 2024. We conducted a systematic review and meta-analysis pooling dichotomous data using risk ratio (RR) with a 95% confidence interval (CI). All analyses were performed using R V. 4.3.1.

Results.
We included five studies with a total of 12,785 patients. Comparing high NPS (3-4) to low NPS (0-2), high NPS (3-4) was significantly associated with an increased incidence of overall mortality (RR: 2.21, 95% CI [1.85, 2.65], P < 0.01), shock (RR: 1.85, 95% CI [1.33, 2.57], P < 0.01), acute kidney injury (RR: 1.54, 95% CI [1.15, 2.08], P < 0.01), left ventricular thrombus (RR: 2.93, 95% CI [1.44, 5.94], P < 0.01), and no-reflow (RR: 1.35, 95% CI [1.17, 1.57], P < 0.01). However, there was no significant difference between high NPS (3-4) and low NPS (0-2) regarding in-hospital mortality (RR: 1.82, 95% CI [0.99, 3.37], P = 0.06).

Conclusion.
Our meta-analysis highlights the importance of evaluating inflammation and malnutrition status in STEMI and shows that routine blood tests can provide prognostic insights. NPS can help predict different clinical outcomes in STEMI patients undergoing PPCI. While it does not affect in-hospital mortality, its simplicity and accessibility make it useful for clinical risk assessment and long-term prognosis. Further studies are needed to investigate its predictive value further.