title: How does coronary stent implantation impact on the status of the microcirculation during primary percutaneous coronary intervention in patients with ST-elevation myocardial infarction?
abstract: OBJECTIVE
  Primary percutaneous coronary intervention (PPCI) is the optimal treatment for patients presenting with ST-elevation myocardial infarction (STEMI). An elevated index of microcirculatory resistance (IMR) reflects microvascular function and when measured after PPCI, it can predict an adverse clinical outcome. We measured coronary microvascular function in STEMI patients and compared sequential changes before and after stent implantation.
  
  
  RESULTS
  In 85 STEMI patients, fractional flow reserve, coronary flow reserve, and IMR were measured using a pressure wire (Certus, St Jude Medical, St Paul, MN, USA) immediately before and after stent implantation. Stenting significantly improved all of the measured parameters of coronary physiology including IMR from 67.7 [interquartile range (IQR): 56.2-95.8] to 36.7 (IQR: 22.7-59.5), P < 0.001. However, after stenting, IMR remained elevated (>40) in 28 (32.9%) patients. In 15 of these patients (17.6% of the cohort), only a partial reduction in IMR occurred and these patients were more likely to be late presenters (pain to wire time >6 h). The extent of jeopardized myocardium [standardized beta: -0.26 (IMR unit/Bypass Angioplasty Revascularization Investigation score unit), P: 0.009] and pre-stenting IMR [standardized beta: -0.34 (IMR unit), P: 0.001] predicted a reduction in IMR after stenting (ΔIMR = post-stenting IMR - pre-stenting IMR), whereas thrombotic burden [standardized beta: 0.24 (IMR unit/thrombus score unit), P: 0.01] and deployed stent volume [standardized beta: 0.26 (IMR unit/mm(3) of stent), P: 0.01] were associated with a potentially deleterious increase in IMR.
  
  
  CONCLUSIONS
  Improved perfusion of the myocardium by stent deployment during PPCI is not universal. The causes of impaired microvascular function at the completion of PPCI treatment are heterogeneous, but can reflect a later clinical presentation and/or the location and extent of the thrombotic burden.
authors.affiliation: Oxford Heart Centre, NIHR Biomedical Research Centre, Oxford University Hospitals, Headley Way, Oxford OX39DU, UK.
authors.forename: Giovanni Luigi
authors.initials: GL
authors.lastname: De Maria
authors.affiliation: Oxford Heart Centre, NIHR Biomedical Research Centre, Oxford University Hospitals, Headley Way, Oxford OX39DU, UK Department of Cardiology, LuzernerKantonsspital, Luzern, Switzerland.
authors.forename: Florim
authors.initials: F
authors.lastname: Cuculi
authors.affiliation: Oxford Heart Centre, NIHR Biomedical Research Centre, Oxford University Hospitals, Headley Way, Oxford OX39DU, UK.
authors.forename: Niket
authors.initials: N
authors.lastname: Patel
authors.affiliation: Oxford Heart Centre, NIHR Biomedical Research Centre, Oxford University Hospitals, Headley Way, Oxford OX39DU, UK.
authors.forename: Sam
authors.initials: S
authors.lastname: Dawkins
authors.affiliation: Oxford Heart Centre, NIHR Biomedical Research Centre, Oxford University Hospitals, Headley Way, Oxford OX39DU, UK.
authors.forename: Gregor
authors.initials: G
authors.lastname: Fahrni
authors.affiliation: Oxford Heart Centre, NIHR Biomedical Research Centre, Oxford University Hospitals, Headley Way, Oxford OX39DU, UK.
authors.forename: George
authors.initials: G
authors.lastname: Kassimis
authors.affiliation: Acute Vascular Imaging Centre, Radcliffe Department of Medicine, University of Oxford, Oxford, UK Division of Cardiovascular Medicine, BHF Centre of Research Excellence, University of Oxford, Oxford, UK.
authors.forename: Robin P
authors.initials: RP
authors.lastname: Choudhury
authors.affiliation: Oxford Heart Centre, NIHR Biomedical Research Centre, Oxford University Hospitals, Headley Way, Oxford OX39DU, UK.
authors.forename: John C
authors.initials: JC
authors.lastname: Forfar
authors.affiliation: Oxford Heart Centre, NIHR Biomedical Research Centre, Oxford University Hospitals, Headley Way, Oxford OX39DU, UK.
authors.forename: Bernard D
authors.initials: BD
authors.lastname: Prendergast
authors.affiliation: Oxford Heart Centre, NIHR Biomedical Research Centre, Oxford University Hospitals, Headley Way, Oxford OX39DU, UK.
authors.forename: Keith M
authors.initials: KM
authors.lastname: Channon
authors.affiliation: Oxford Heart Centre, NIHR Biomedical Research Centre, Oxford University Hospitals, Headley Way, Oxford OX39DU, UK.
authors.forename: Rajesh K
authors.initials: RK
authors.lastname: Kharbanda
authors.affiliation: Oxford Heart Centre, NIHR Biomedical Research Centre, Oxford University Hospitals, Headley Way, Oxford OX39DU, UK adrian.banning@ouh.nhs.uk.
authors.forename: Adrian P
authors.initials: AP
authors.lastname: Banning
mesh_terms: D000925:Anticoagulants / Q000627:therapeutic use; D003326:Coronary Circulation / Q000502:physiology*; D003328:Coronary Thrombosis / Q000503:physiopathology / Q000628:therapy; D004359:Drug Therapy, Combination; D005260:Female; D006801:Humans; D008297:Male; D008833:Microcirculation / Q000502:physiology*; D008875:Middle Aged; D009203:Myocardial Infarction / Q000503:physiopathology / Q000628:therapy*; D009204:Myocardial Revascularization / Q000379:methods; D062645:Percutaneous Coronary Intervention; D011446:Prospective Studies; D015607:Stents; D016896:Treatment Outcome; D014655:Vascular Resistance / Q000502:physiology
chemical_list: D000925:Anticoagulants
keywords: Distal embolization; Index of microcirculatory resistance; ST-elevation myocardial infarction; Stent