title: Increase in ultrasonic intensity of blood speckle across moderate coronary artery stenosis is an independent predictor of functional coronary artery stenosis measured by fractional flow reserve: pilot study.
abstract: OBJECTIVE
  The degree of coronary artery stenosis should be assessed both anatomically and functionally. We observed that the intensity of blood speckle (IBS) on intravascular ultrasound (IVUS) is low proximal to a coronary artery stenosis, and high distal to the stenosis. We defined step-up IBS as the distal minus the proximal IBS, and speculated that this new parameter could be used for the functional evaluation of stenosis on IVUS. The aims of this study were to assess the relationships between step-up IBS and factors that affect coronary blood flow, and between step-up IBS and fractional flow reserve (FFR).
  
  
  RESULTS
  This study enrolled 36 consecutive patients with angina who had a single moderate stenosis in the left anterior descending artery. All patients were evaluated by integrated backscatter IVUS and intracoronary pressure measurements. FFR was calculated from measurements using a coronary pressure wire during hyperemia. Conventional gray-scale IVUS images were recorded, and integrated backscatter was measured in three cross-sectional slices proximal and distal to the stenosis. Step-up IBS was calculated as (mean distal integrated backscatter value) - (mean proximal integrated backscatter value). Stepwise multiple linear regression analysis showed that the heart rate (r = 0.45, P = 0.005), ejection fraction (r = -0.39, P = 0.01), and hemoglobin level (r = -0.32, P = 0.04) were independently correlated with step-up IBS, whereas proximal and distal IBS were not associated with these factors. There was a strong inverse correlation between step-up IBS and FFR (r = -0.84, P < 0.001), which remained significant on stepwise multiple linear regression analysis.
  
  
  CONCLUSIONS
  The newly defined parameter of step-up IBS is potentially useful for the functional assessment of coronary artery stenosis.
authors.affiliation: Department of Cardiology, Saitama Medical University, International Medical Center, Saitama, Japan.
authors.forename: Jun
authors.initials: J
authors.lastname: Tanno
authors.affiliation: Department of Cardiology, Saitama Medical University, International Medical Center, Saitama, Japan.
authors.forename: Shintaro
authors.initials: S
authors.lastname: Nakano
authors.affiliation: Department of Cardiology, Juntendo University School of Medicine, Tokyo, Japan.
authors.forename: Takatoshi
authors.initials: T
authors.lastname: Kasai
authors.affiliation: Department of Cardiovascular Medicine, Kitasato University School of Medicine, Kanagawa, Japan.
authors.forename: Junya
authors.initials: J
authors.lastname: Ako
authors.affiliation: New Tokyo Hospital, Chiba, Japan.
authors.forename: Sunao
authors.initials: S
authors.lastname: Nakamura
authors.affiliation: Department of Cardiology, Saitama Medical University, International Medical Center, Saitama, Japan.
authors.forename: Takaaki
authors.initials: T
authors.lastname: Senbonmatsu
authors.affiliation: Department of Cardiology, Saitama Medical University, International Medical Center, Saitama, Japan.
authors.forename: Shigeyuki
authors.initials: S
authors.lastname: Nishimura
mesh_terms: D000368:Aged; D017023:Coronary Angiography; D023921:Coronary Stenosis / Q000000981:diagnostic imaging* / Q000473:pathology* / Q000503:physiopathology; D003331:Coronary Vessels / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D005260:Female; D053805:Fractional Flow Reserve, Myocardial; D006339:Heart Rate; D006801:Humans; D006940:Hyperemia / Q000000981:diagnostic imaging / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D013318:Stroke Volume; D014463:Ultrasonography