title: Zero-Flow Pressure Measured Immediately After Primary Percutaneous Coronary Intervention for ST-Segment Elevation Myocardial Infarction Provides the Best Invasive Index for Predicting the Extent of Myocardial Infarction at 6 Months: An OxAMI Study (Oxford Acute Myocardial Infarction).
abstract: OBJECTIVE
  The aim of this study was to define which measure of microvascular best predicts the extent of left ventricular (LV) infarction.
  
  
  BACKGROUND
  Microvascular injury after ST-segment elevation myocardial infarction (STEMI) is an important determinant of outcome. Several invasive measures of the microcirculation at primary percutaneous coronary intervention (PPCI) have been described. One such measure is zero-flow pressure (Pzf), the calculated pressure at which coronary flow would cease.
  
  
  METHODS
  In 34 STEMI patients, Pzf, hyperemic microvascular resistance (hMR), and index of microcirculatory resistance (IMR) were derived using thermodilution flow/pressure and Doppler flow/pressure wire assessment of the infarct-related artery following PPCI. The extent of infarction was determined by blinded late gadolinium enhancement on cardiac magnetic resonance at 6 months post-PPCI. Infarction of ≥24% total LV mass was used as a categorical cutoff in receiver-operating characteristic curve analysis.
  
  
  RESULTS
  Pzf was superior to both hMR and IMR for predicting ≥24% infarction area under the curve: 0.94 for Pzf versus 0.74 for hMR (p = 0.04) and 0.54 for IMR (p = 0.003). Pzf ≥42 mm Hg was the optimal cutoff value, offering 100% sensitivity and 73% specificity. Patients with Pzf ≥42 mm Hg also had a lower salvage index (61.3 ± 8.1 vs. 44.4 ± 16.8, p = 0.006) and 6-month ejection fraction (62.4 ± 3.6 vs. 49.9 ± 9.6, p = 0.002). In addition, there were significant direct relationships between Pzf and troponin area under the curve (rho = 0.55, p = 0.002), final infarct mass (rho = 0.75, p < 0.0001), percentage of LV infarction and percent transmurality of infarction (rho = 0.77 and 0.74, respectively, p < 0.0001), and inverse relationships with myocardial salvage index (rho = -0.53, p = 0.01) and 6-month ejection fraction (rho = -0.73, p = 0.0001).
  
  
  CONCLUSIONS
  Pzf measured at the time of PPCI is a better predictor of the extent of myocardial infarction than hMR or IMR. Pzf may provide important prognostic information at the time of PPCI and merits further investigation in clinical studies with relevant outcome measures.
authors.affiliation: Oxford Heart Centre, Oxford University Hospitals, Oxford, United Kingdom.
authors.forename: Niket
authors.initials: N
authors.lastname: Patel
authors.affiliation: International Centre for Circulatory Health, National Heart and Lung institute, Imperial College, London, United Kingdom.
authors.forename: Ricardo
authors.initials: R
authors.lastname: Petraco
authors.affiliation: Acute Vascular Imaging Centre, 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: George
authors.initials: G
authors.lastname: Kassimis
authors.affiliation: Oxford Heart Centre, Oxford University Hospitals, Oxford, United Kingdom.
authors.forename: Giovanni Luigi
authors.initials: GL
authors.lastname: De Maria
authors.affiliation: Division of Cardiovascular Medicine, University of Oxford, Oxford, United Kingdom.
authors.forename: Sam
authors.initials: S
authors.lastname: Dawkins
authors.affiliation: Division of Cardiovascular Medicine, University of Oxford, Oxford, United Kingdom.
authors.forename: Regent
authors.initials: R
authors.lastname: Lee
authors.affiliation: Oxford Heart Centre, Oxford University Hospitals, Oxford, United Kingdom.
authors.forename: Bernard D
authors.initials: BD
authors.lastname: Prendergast
authors.affiliation: Acute Vascular Imaging Centre, University of Oxford, Oxford, United Kingdom.
authors.forename: Robin P
authors.initials: RP
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: Division of Cardiovascular Medicine, University of Oxford, Oxford, United Kingdom.
authors.forename: Keith M
authors.initials: KM
authors.lastname: Channon
authors.affiliation: International Centre for Circulatory Health, National Heart and Lung institute, Imperial College, London, United Kingdom.
authors.forename: Justin
authors.initials: J
authors.lastname: Davies
authors.affiliation: Oxford Heart Centre, Oxford University Hospitals, Oxford, United Kingdom.
authors.forename: Adrian P
authors.initials: AP
authors.lastname: Banning
authors.affiliation: Oxford Heart Centre, Oxford University Hospitals, Oxford, United Kingdom; Division of Cardiovascular Medicine, University of Oxford, Oxford, United Kingdom. Electronic address: rajesh.kharbanda@ouh.nhs.uk.
authors.forename: Rajesh K
authors.initials: RK
authors.lastname: Kharbanda
mesh_terms: D000368:Aged; D019540:Area Under Curve; D006328:Cardiac Catheterization; D003287:Contrast Media; D017023:Coronary Angiography; D003326:Coronary Circulation; D003331:Coronary Vessels / Q000503:physiopathology*; D015150:Echocardiography, Doppler; D004739:England; D005260:Female; D006801:Humans; D019028:Magnetic Resonance Imaging, Cine; D008297:Male; D008833:Microcirculation; D008875:Middle Aged; D009203:Myocardial Infarction / Q000175:diagnosis / Q000503:physiopathology / Q000628:therapy*; D009206:Myocardium / Q000473:pathology*; D062645:Percutaneous Coronary Intervention / Q000009:adverse effects; D011237:Predictive Value of Tests; D012372:ROC Curve; D018570:Risk Assessment; D012307:Risk Factors; D013815:Thermodilution; D013997:Time Factors; D016896:Treatment Outcome; D014655:Vascular Resistance; D016277:Ventricular Function, Left
chemical_list: D003287:Contrast Media
keywords: angioplasty; magnetic resonance imaging; microcirculation; myocardial infarction; physiology