Effect of Pre-stenting Intracoronary Pharmacological Therapy on the No-Reflow/Slow-Flow Phenomenon in Patients with Acute Coronary Syndrome Undergoing Percutaneous Coronary Intervention: A Prospective Observational Comparative Study

Abstract

Objective: To evaluate the effect of pre-stenting intracoronary pharmacological therapy on the incidence of the no-reflow/slow-flow phenomenon in patients with acute coronary syndrome (ACS) undergoing percutaneous coronary intervention (PCI) and to identify independent clinical and angiographic predictors associated with its occurrence. Methodology: This prospective observational comparative study was conducted between September 2025 and February 2026 included adult patients with ACS undergoing PCI. Patients were categorized into an intracoronary medication group (n = 157) and a control group (n = 166) according to routine operator-directed clinical practice. Intracoronary pharmacological therapy included adenosine, nitroglycerin, nicorandil, or combinations administered immediately before stent deployment. The primary outcome was the occurrence of no-reflow/slow-flow, defined as final Thrombolysis in Myocardial Infarction (TIMI) flow grade ≤2 and/or myocardial blush grade (MBG) ≤1 in the absence of mechanical obstruction. Results: Among the 323 patients, no-reflow/slow-flow occurred in 78 (24.1%). The incidence was 22.3% in the intracoronary medication group and 25.9% in the control group, with no statistically significant difference (p = 0.470). After adjustment for potential confounders, intracoronary pharmacological therapy was not independently associated with a reduced risk of no-reflow/slow-flow (adjusted OR 0.88, 95% CI 0.56–1.39; p = 0.590). STEMI presentation, high thrombus burden, impaired baseline TIMI flow (≤1), diabetes mellitus, and chronic kidney disease were identified as independent predictors of no-reflow/slow-flow (all p < 0.05). Conclusion: Routine pre-stenting intracoronary pharmacological therapy was not associated with a significant reduction in the incidence of the no-reflow/slow-flow phenomenon among patients with ACS undergoing PCI. The occurrence of no-reflow was primarily influenced by baseline clinical and angiographic characteristics rather than prophylactic intracoronary vasodilator administration.