title: Pressure-wire based assessment of microvascular resistance using calibrated upstream balloon obstruction: a predictor of myocardial viability.
abstract: OBJECTIVE
  We assess microvascular integrity as a marker of myocardial viability after coronary stenting, using only a pressure guidewire.
  
  
  BACKGROUND
  Microvascular integrity generally is not assessed using pressure-only guidewires because the transducer lies upstream of microvasculature. We partially inflate a balloon inside a coronary stent to achieve a specific normalized pressure drop at rest (distal coronary/aortic pressure = 0.8) and then infuse a vasodilator, to render the wire sensitive to microvascular function. We hypothesize that the further decline in pressure (ΔFFR(0.8) ) predicts MRI myocardial viability.
  
  
  METHODS
  We studied 29 subjects with acute coronary syndrome including myocardial infarction. After successful culprit stenting, the resting coronary/aortic pressure was set to 0.8 using temporary balloon obstruction. ΔFFR(0.8) was defined as 0.8-(distal coronary/aortic pressures) during adenosine-induced hyperemia. The average transmural extent of infarction was defined as the average area of MRI late gadolinium enhancement (after 2.8 ± 1.5 days) divided by the corresponding full thickness of the gadolinium enhanced sector in short axis slices, and was compared with ΔFFR(0.8) .
  
  
  RESULTS
  ΔFFR(0.8) corresponded inversely and linearly with the average transmural extent of infarction (r(2) = 0.65, P < 0.001). We found that a transmural extent of infarction of 0.50 corresponded to a ΔFFR(0.8) threshold of 0.1, and had high sensitivity and specificity (100% and 94.4%, respectively).
  
  
  CONCLUSIONS
  Using only an upstream pressure-sensitive guidewire and a partially obstructing balloon during pharmacologic hyperemia, we were able to predict MRI myocardial viability with high accuracy after relief of epicardial stenosis. With further validation, this may prove a useful clinical prognostic tool after percutaneous intervention.
authors.affiliation: Division of Cardiology, Department of Internal Medicine and Research Institute for Convergence of Biomedical Science and Technology, Pusan National University Yangsan Hospital.
authors.forename: June-Hong
authors.initials: JH
authors.lastname: Kim
authors.forename: Ju-Hyun
authors.initials: JH
authors.lastname: Park
authors.forename: Kiseok
authors.initials: K
authors.lastname: Choo
authors.forename: Sung-Kook
authors.initials: SK
authors.lastname: Song
authors.forename: Jung-Su
authors.initials: JS
authors.lastname: Kim
authors.forename: Young-Hyun
authors.initials: YH
authors.lastname: Park
authors.forename: Jun
authors.initials: J
authors.lastname: Kim
authors.forename: Kook-Jin
authors.initials: KJ
authors.lastname: Chun
authors.forename: Dongcheul
authors.initials: D
authors.lastname: Han
authors.forename: Anthony Z
authors.initials: AZ
authors.lastname: Faranesh
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Lederman
mesh_terms: D054058:Acute Coronary Syndrome / Q000175:diagnosis* / Q000473:pathology / Q000503:physiopathology / Q000628:therapy; D000241:Adenosine; D000368:Aged; D015906:Angioplasty, Balloon, Coronary / Q000295:instrumentation; D001794:Blood Pressure; D002138:Calibration; D006328:Cardiac Catheterization / Q000295:instrumentation / Q000592:standards; D062906:Cardiac Catheters; D016009:Chi-Square Distribution; D005260:Female; D053805:Fractional Flow Reserve, Myocardial; D006801:Humans; D006940:Hyperemia / Q000503:physiopathology; D016014:Linear Models; D019028:Magnetic Resonance Imaging, Cine; D008297:Male; D008833:Microcirculation; D008875:Middle Aged; D015999:Multivariate Analysis; D009203:Myocardial Infarction / Q000175:diagnosis* / Q000473:pathology / Q000503:physiopathology / Q000628:therapy; D009206:Myocardium / Q000473:pathology*; D011237:Predictive Value of Tests; D011446:Prospective Studies; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D015607:Stents; D014022:Tissue Survival; D014160:Transducers, Pressure; D016896:Treatment Outcome; D014655:Vascular Resistance; D014665:Vasodilator Agents
chemical_list: D014665:Vasodilator Agents; D000241:Adenosine