Coronary Endothelial and Microvascular Function Distal to Polymer-Free and Endothelial Cell-Capturing Drug-Eluting Stents. the Randomized FUNCOMBO Trial.

Introduction and objectives: The vasomotor function of new-generation drug-eluting stents designed to enhance stent healing and reendothelialization is unknown. This study aimed to compare the endothelial function of the infarct-related artery (IRA) treated with bioactive circulating endothelial progenitor cell-capturing sirolimus-eluting stents (COMBO) vs polymer-free biolimus-eluting stents (BioFreedom) in ST-segment elevation myocardial infarction patients at 6 months. Secondary objectives were to compare the microcirculatory function of the IRA and stent healing at 6 months. Methods: Sixty patients were randomized to bioactive sirolimus-eluting stent vs polymer-free biolimus-eluting stents implantation. At 6 months, patients underwent coronary angiography with vasomotor, microcirculatory and optical coherence tomography examinations. Endothelial dysfunction of the distal coronary segment was defined as > 4% vasoconstriction to intracoronary acetylcholine infusion. Results: Endothelial dysfunction was similarly observed between groups (64.0% vs 62.5%, respectively; P = .913). Mean lumen diameter decreased by 16.0 +/- 20.2% vs 16.1 +/- 21.6% during acetylcholine infusion (P = .983). Microcirculatory function was similar in the 2 groups: coronary flow reserve was 3.23 +/- 1.77 vs 3.23 +/- 1.62 (P = .992) and the index of microcirculatory resistance was 24.8 +/- 16.8 vs 21.3 +/- 12.0 (P = .440). Optical coherence tomography findings were similar: uncovered struts (2.3% vs 3.2%; P = .466), malapposed struts (0.1% vs 0.3%; P = .519) and major evaginations (7.1% vs 5.6%; P = .708) were observed in few cases. Conclusions: Endothelial dysfunction of the IRA was frequent and was similarly observed with new -generation drug-eluting stents designed to enhance stent reendothelialization at 6 months. Endothelial dysfunction was observed despite almost preserved microcirculatory function and complete stent coverage. Larger and clinically powered studies are needed to assess the role of residual endothelial dysfunction in ST-segment elevation myocardial infarction patients. Registered in ClinicalTrials.gov: NCT04202172