Inflammatory and Hematological Indices in Diabetic STEMI Patients Undergoing Primary PCI

Overview

ST-segment Elevation Myocardial Infarction (STEMI) remains a major cause of mortality despite the adoption of Primary Percutaneous Coronary Intervention (PPCI) as the standard treatment. However, outcomes still vary significantly among patients, especially between diabetic and non-diabetic cohorts. The research question driving this study is: Can hematologic, inflammatory, and thrombotic indices serve as reliable prognostic tools in predicting the no-reflow phenomenon and coronary artery disease (CAD) severity in STEMI patients, particularly among those with diabetes mellitus? Recent literature identifies inflammation as a key contributor to the pathogenesis and outcomes of Acute Coronary Syndrome (ACS), including the no-reflow phenomenon and Major Adverse Cardiovascular Events (MACE). Markers such as C-reactive protein (CRP), Neutrophil-to-Albumin Ratio (NAR), Red Cell Distribution Width (RDW), Platelet Distribution Width (PDW), Hemoglobin-to-Red Cell Distribution Width ratio (Hb/RDW), and the RDW/PDW ratio have shown individual correlations with poor outcomes. Emerging indices such as the Systemic Immune-Inflammation Index (SII) and the Systemic Inflammatory Response Index (SIRI) further integrate immune and inflammatory components and have shown promise in early risk stratification. The current strategy in many cardiac centers relies on angiographic and clinical indicators, which may be insufficient for individualized risk prediction. Hence, incorporating accessible and cost-effective blood-based markers could significantly enhance prognostic accuracy. The rationale of this research lies in comparing these indices in diabetic versus non-diabetic STEMI patients, aiming to stratify risk, predict no-reflow, assess coronary artery disease burden using the SYNTAX score, and identify those at risk for early adverse outcomes.

ST-segment Elevation Myocardial Infarction (STEMI) is a critical form of Acute Coronary Syndrome (ACS), resulting from abrupt plaque rupture and thrombotic coronary occlusion. Despite the widespread application of Primary Percutaneous Coronary Intervention (PPCI), STEMI remains one of the leading causes of mortality. Therefore, early stratification and prediction of outcomes is essential. Recent evidence highlights that, in addition to thrombosis, inflammation plays a crucial role in the pathophysiology of ACS. This has prompted increasing interest in novel inflammatory and hematological biomarkers as promising prognostic tools. These indices are simple, cost-effective, and clinically relevant for outcome prediction. The markers evaluated in this study include both inflammatory indices (e.g., C-reactive protein \[CRP\], Neutrophil-to-Albumin Ratio \[NAR\]) and thrombotic/hematological indices (e.g., Red Cell Distribution Width \[RDW\], Platelet Distribution Width \[PDW\], Hemoglobin-to-Red Cell Distribution Width ratio \[Hb/RDW\], and RDW/PDW ratio). Some of these have already been established as strong predictors of adverse outcomes in STEMI patients, while others remain under investigation. Moreover, their differential prognostic value in diabetic versus non-diabetic STEMI populations remains an area of ongoing research. Among the markers for inflammation, C-reactive protein (CRP) has been shown to be strongly associated with increased in-hospital mortality among STEMI patients. Another important marker is the Neutrophil-to-Albumin Ratio (NAR), which combines indicators of systemic inflammation and nutritional status. Higher NAR levels have been linked with poor in-hospital outcomes in STEMI. This study also evaluates hematological and thrombotic indices. Red Cell Distribution Width (RDW), an indicator of anisocytosis, is a well-studied parameter. Increased RDW levels have been associated with worse outcomes in cardiovascular diseases (CVD) and heart failure. Platelet Distribution Width (PDW)-a marker of platelet activation and heterogeneity-has been identified as a strong independent predictor of the no-reflow phenomenon. An elevated RDW/PDW ratio is thought to represent systemic stress and a prothrombotic state, making it a compelling predictor of poor clinical and angiographic outcomes such as no-reflow. The Hemoglobin-to-Red Cell Distribution Width ratio (Hb/RDW) is a novel indicator. A lower Hb/RDW ratio reflects reduced tissue oxygenation and erythropoietic dysfunction, both of which are linked to poor myocardial recovery, no-reflow, and higher SYNTAX scores. The no-reflow phenomenon, which these markers help anticipate, is defined as inadequate myocardial perfusion through a segment of the coronary circulation in the absence of mechanical obstruction. In addition to traditional markers, the Systemic Immune-Inflammation Index (SII) and the Systemic Inflammatory Response Index (SIRI) have recently gained attention. Both are calculated using peripheral blood counts and provide insight into the interplay between inflammation, thrombosis, and immune regulation: Systemic Immune-Inflammation Index (SII): Platelet count × Neutrophil count / Lymphocyte count. This index combines neutrophil-driven inflammation, platelet-related thrombosis, and lymphocyte-mediated immune regulation. SII has been recognized as a powerful predictor of no-reflow, MACE, and mortality in cardiovascular patients. Systemic Inflammatory Response Index (SIRI): Monocyte count × Neutrophil count / Lymphocyte count. This index reflects systemic inflammation and monocyte activity in atherosclerosis. Elevated SIRI has been associated with higher SYNTAX scores, no-reflow, and adverse cardiovascular outcomes. Thus, exploring the association between different hematologic-inflammatory indices-including Hb/RDW, RDW/PDW, NAR, SII, SIRI, Neutrophil-to-Lymphocyte Ratio (NLR), and Platelet-to-Lymphocyte Ratio (PLR)-with no-reflow, coronary artery disease severity, and short-term outcomes in diabetic versus non-diabetic STEMI patients undergoing PPCI remains clinically relevant and needed.