The Association of Plasma Osmolarity With No-Reflow in Patients With ST-Segment Elevation Myocardial Infarction: A Retrospective Cohort Study.

Background The no-reflow phenomenon is a serious complication that can occur after primary percutaneous coronary intervention (PCI) in patients with ST-segment elevation myocardial infarction (STEMI), leading to poor myocardial reperfusion and adverse outcomes. Objective This study aims to evaluate the association between admission plasma osmolarity and the occurrence of the no-reflow phenomenon in patients with STEMI undergoing primary PCI. Methods This retrospective cohort study was conducted at Shalamar Hospital, Lahore, Pakistan from February 2022 to February 2025. The study included 486 consecutive patients diagnosed with STEMI who underwent primary PCI. Patients aged ≥ 18 years, confirmed diagnosis of STEMI based on chest pain duration of more than 30 minutes, ST-segment elevation of ≥1 mm in at least two contiguous ECG leads, and elevated cardiac biomarkers were included in the study. Results In this study of 486 STEMI patients undergoing primary PCI, high plasma osmolarity (>295 mOsm/L) was significantly associated with an increased incidence of no-reflow (31.1%) compared to normal (13.4%) and low osmolarity groups (9.2%). The incidence of no-reflow was significantly higher in the high osmolarity group (31.1%) compared to the normal (13.4%) and low (9.2%) groups (p < 0.001). High plasma osmolarity was independently associated with an increased risk of no-reflow (adjusted odds ratio 2.94; 95% CI: 1.61-5.38; p < 0.001). Conclusion It is concluded that elevated plasma osmolarity is an independent predictor of the no-reflow phenomenon in STEMI patients undergoing primary PCI. Routine assessment of plasma osmolarity may offer a simple and effective method for early risk stratification, with potential implications for personalized management strategies to improve reperfusion outcomes.