Background: Coronary artery disease (CAD) is a widespread health issue globally, linked to significant morbidity and mortality. While oxidative stress, dysregulated lipid metabolism, and unhealthy lifestyle choices contribute to CAD, recent research highlights the role of immune responses and inflammation. Malnutrition, a modifiable risk factor, notably impacts CAD prognosis. The prognostic nutritional index (PNI), derived from serum albumin and lymphocyte count, predicts outcomes in various diseases. This study aims to elucidate the relationship between malnutrition, as assessed by the PNI score, and the functional significance of coronary artery stenosis, evaluated by fractional flow reserve (FFR) measurements.

Methods: A retrospective analysis involved 232 patients with single intermediate-grade coronary stenosis who underwent FFR measurement between January 2022 and January 2024. Prognostic nutritional index values were calculated from serum albumin and lymphocyte counts. Patients were divided into 2 groups based on FFR values.

Results: Patients with hemodynamically significant coronary stenosis (FFR ≤ 0.80) exhibited higher inflammatory markers and triglycerides, while those with FFR > 0.80 showed elevated albumin and PNI levels. Triglycerides and PNI emerged as independent predictors of significant coronary stenosis.

Conclusions: This study demonstrates that PNI is independently associated with the functional significance of coronary artery stenosis as determined by FFR. Since lymphocytes, total protein and albumin values, which are readily available from routine blood tests, form the basis for PNI, this index can be easily used in clinical settings to predict hemodynamically significant coronary artery stenosis. However, the results of this study should be further expanded and validated through studies involving larger samples and prospective designs.