Abstract Body (Do not enter title and authors here): Background: Occurring in 0.6% to 10% of percutaneous coronary interventions (PCI), no-reflow is a complication associated with poor outcomes like myocardial infarction extension and death. The mechanism behind no-reflow is complex and likely multifactorial, and several drugs have been described for its management including intracoronary epinephrine (ICE) at doses ranging from 50 to 400 µg.

Hypothesis: We hypothesize that supraselective administration of ICE at very low doses could be effective in the successful management of no-reflow.

Methods: This single-center case series from Bucaramanga, Colombia (August 2021-October 2023) reports on 9 patients with/without ST-segment elevation myocardial infarction who underwent PCI and developed no-reflow. As first-line therapy for no-reflow management, supraselective administration of 5 to 50 µg of ICE was performed through an ad hoc fenestrated angioplasty balloon with a two-way drug perfusion technique (proximal to distal, and distal to proximal) at an approximate rate of 2 µg/min. All patients received a 1000 µg intracoronary bolus of Tirofiban during the procedure, and an IV infusion of 0.15 µg/kg/min was continued up to 24 hours postangioplasty.

Results: The mean age of patients was 72.7±10.6 years, and 8 out of 9 patients were male. The mean LVEF was 34±11.3% before PCI. Patients received varying doses of ICE (5, 10, 20, 40 and 50 µg), 7 received it as the first-line treatment, while 2 received it as a second-line option after 360 µg of intracoronary adenosine failed to improve blood flow. TIMI 2 flow (4 patients) and TIMI 3 flow (5 patients) were achieved with no consistent association between higher ICE doses and achieving TIMI 3 flow. All 9 patients were discharged alive from the Cath Lab. However, one patient with LVEF 20% died of pulmonary edema 7 hours postangioplasty. The mean heart rate before and after the procedure was 78±20.8 bpm and 84±18.3 bpm respectively. No severe cardiac arrhythmias were observed. Transient inotropic support with a norepinephrine infusion was needed by 2 patients.

Conclusion: The supraselective administration of ICE at very low doses (5-50 µg) resolved no-reflow in 100% of patients with acute coronary syndrome. We propose the use of this drug at very low doses as a first-line therapy for the management of coronary no-reflow, as well as the development of future randomized control trials to evaluate its effectiveness, and compare it to current therapies, in a larger population.