Pan-immune-inflammation value for risk stratification of adverse cardiovascular outcomes in acute coronary syndrome undergoing percutaneous coronary intervention: a systematic review and meta-analysis

Background Patients with acute coronary syndrome (ACS) undergoing percutaneous coronary intervention (PCI) remain at residual cardiovascular risk. The pan-immune-inflammation value (PIV), integrating neutrophil, platelet, monocyte, and lymphocyte counts, has been proposed as a candidate prognostic biomarker in this population, but the evidence has not been formally synthesised. We evaluated the prognostic and discriminatory value of PIV in adults with ACS undergoing PCI. Methods PubMed/MEDLINE, Embase, Web of Science Core Collection, the Cochrane Library, Scopus, and CNKI were searched from inception, supplemented by trial registries, Google Scholar, and reference hand-searching. Cohort studies reporting associations between PIV and major adverse cardiovascular events (MACE; primary outcome), all-cause mortality, cardiovascular or cardiac mortality, angiographic no-reflow or slow-flow, or post-contrast renal injury were eligible. Two reviewers independently performed study selection, data extraction, and QUIPS risk-of-bias assessment. Adjusted hazard ratios, odds ratios, and AUC values were pooled separately using random-effects models; certainty was rated with GRADE. PROSPERO: CRD420261378751. Results Nineteen cohort studies (n = 18,715) were included. Higher PIV was associated with study-defined MACE (adjusted HR 1.65, 95% CI 1.20–2.27; k = 2; I² = 0.0%; low certainty) and all-cause mortality (HR 3.51, 95% CI 2.15–5.74; k = 2; I² = 0.0%; moderate certainty). A single study reported an association with cardiac mortality (HR 3.24, 95% CI 1.34–7.81; low certainty). PIV showed consistent discrimination for no-reflow or slow-flow (AUC 0.828, 95% CI 0.808–0.846; k = 2; I² = 0.0%; moderate certainty) and heterogeneous discrimination for post-contrast renal injury (AUC 0.771, 95% CI 0.617–0.875; k = 5; I² = 95.1%; very low certainty). Risk of bias was moderate in 16 studies and high in three. Conclusion Elevated PIV may be associated with adverse cardiovascular outcomes in ACS patients undergoing PCI, particularly long-term all-cause mortality and angiographic no-reflow or slow-flow. However, evidence is limited by observational designs, small numbers of studies for several outcomes, heterogeneous cut-offs, and risk-of-bias concerns. PIV should be regarded as a promising supplementary marker requiring prospective multicentre validation, comparison with established inflammatory indices, and assessment of incremental value beyond GRACE or TIMI before routine clinical use. Systematic Review Registration https://www.crd.york.ac.uk/prospero/ , identifier CRD420261378751