title: Impact of microvascular obstruction on the assessment of coronary flow reserve, index of microcirculatory resistance, and fractional flow reserve after ST-segment elevation myocardial infarction.
abstract: BACKGROUND
  Invasive assessment of coronary physiology (IACP) offers important prognostic insights in ST-segment elevation myocardial infarction (STEMI) but the dynamics of coronary recovery are poorly understood.
  
  
  OBJECTIVE
  This study sought to examine the evolution of coronary flow reserve (CFR), index of microcirculatory resistance (IMR), ratio of distal coronary pressure (Pd) to mean aortic pressure (Pa), and fractional flow reserve (FFR) in patients undergoing primary percutaneous coronary intervention (PPCI).
  
  
  METHODS
  82 patients with STEMI underwent IACP at PPCI. Repeat IACP was performed in 61 patients (74%) at day 1 and in 46 patients (56%) at 6 months. Contrast-enhanced cardiac magnetic resonance imaging (CMR) was performed in 45 patients (55%) at day 1 and in 41 patients (50%) at 6 months. Changes in IACP were compared between patients with and without microvascular obstruction (MVO) on CMR.
  
  
  RESULTS
  MVO was present in 21 of 45 patients (47%). Patients with MVO had lower CFR at PPCI and day 1 (p < 0.05) and a trend toward higher IMR values (p = 0.07). At 6 months, CFR and IMR were not significantly different between the groups. Baseline flow and Pd/Pa remained stable over time but FFR reduced significantly between PPCI and 6 months (p = 0.008); this reduction was mainly observed in patients with MVO (p = 0.006) but not in those without MVO (p = 0.21).
  
  
  CONCLUSIONS
  In PPCI-treated patients with STEMI, coronary microcirculation begins to recover within 24 h and recovery progresses further by 6 months. FFR significantly reduces from baseline to 6 months. The presence of MVO indicates a highly dysfunctional microcirculation.
authors.affiliation: Oxford Heart Centre, Oxford University Hospitals, Oxford, United Kingdom; Department of Cardiology, Luzerner Kantonsspital, Luzern, Switzerland.
authors.forename: Florim
authors.initials: F
authors.lastname: Cuculi
authors.affiliation: Department of Cardiology, Luzerner Kantonsspital, Luzern, Switzerland.
authors.forename: Giovanni Luigi
authors.initials: GL
authors.lastname: De Maria
authors.affiliation: The Heart Hospital, University College London Hospitals, London, United Kingdom.
authors.forename: Pascal
authors.initials: P
authors.lastname: Meier
authors.affiliation: Department of Cardiovascular Medicine, University of Oxford, Oxford, United Kingdom.
authors.forename: Erica
authors.initials: E
authors.lastname: Dall'Armellina
authors.affiliation: Oxford Heart Centre, Oxford University Hospitals, Oxford, United Kingdom.
authors.forename: Alberto R
authors.initials: AR
authors.lastname: de Caterina
authors.affiliation: Department of Cardiovascular Medicine, University of Oxford, Oxford, United Kingdom.
authors.forename: Keith M
authors.initials: KM
authors.lastname: Channon
authors.affiliation: Oxford Heart Centre, Oxford University Hospitals, Oxford, United Kingdom.
authors.forename: Bernard D
authors.initials: BD
authors.lastname: Prendergast
authors.forename: Robin P
authors.initials: RP
authors.lastname: Choudhury
authors.affiliation: Oxford Acute Vascular Imaging Centre, University of Oxford, Oxford, United Kingdom.
authors.forename: Robin C
authors.initials: RC
authors.lastname: Choudhury
authors.affiliation: Oxford Heart Centre, Oxford University Hospitals, Oxford, United Kingdom.
authors.forename: John C
authors.initials: JC
authors.lastname: Forfar
authors.affiliation: Oxford Heart Centre, Oxford University Hospitals, Oxford, United Kingdom.
authors.forename: Rajesh K
authors.initials: RK
authors.lastname: Kharbanda
authors.affiliation: Oxford Heart Centre, Oxford University Hospitals, Oxford, United Kingdom. Electronic address: adrian.banning@ouh.nhs.uk.
authors.forename: Adrian P
authors.initials: AP
authors.lastname: Banning
mesh_terms: D017023:Coronary Angiography; D003326:Coronary Circulation / Q000502:physiology*; D054059:Coronary Occlusion / Q000150:complications / Q000175:diagnosis / Q000503:physiopathology*; D003331:Coronary Vessels / Q000503:physiopathology*; D004562:Electrocardiography; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D019028:Magnetic Resonance Imaging, Cine; D008297:Male; D008833:Microcirculation / Q000502:physiology*; D008875:Middle Aged; D009203:Myocardial Infarction / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology*; D011379:Prognosis; D011446:Prospective Studies; D020127:Recovery of Function / Q000502:physiology; D012039:Regional Blood Flow / Q000502:physiology*; D014655:Vascular Resistance / Q000502:physiology*
keywords: primary percutaneous coronary intervention