the online version of this article ( doi:10.1007/s40119 - 015 - 0051 - 1 ) contains supplementary material , which is available to authorized users . assessment of intermediate coronary lesions ( 3070% stenosis ) by coronary angiogram has been shown to be a poor predictor of the hemodynamic significance of the lesion . earlier studies had suggested that fractional flow reserve ( ffr)-guided revascularization was superior at reducing major cardiac adverse outcomes when compared with angiogram - guided revascularization [ 24 ] . the 5-year follow - up of the fractional flow reserve versus angiography for multivessel evaluation ( fame ; clinicaltrials.gov identifier , nct00267774 ) trial demonstrated that an ffr - guided approach is associated with a similar risk of major events but with a lower number of stented arteries and less resource use . ffr assessment during coronary angiography is endorsed by the european society of cardiology and the american college of cardiology for identification of hemodynamically significant lesions when non - invasive evidence of myocardial ischemia is unavailable [ 6 , 7 ] . deferral of revascularization is recommended for non - ischemic lesions [ 8 , 9 ] . despite the documented benefits of ffr . this might be especially true in a fee - for - service system , where ffr could result in deferral of revascularization . the veterans health system is unique in that there is no financial incentive to perform revascularization procedures . therefore , at a single - center veterans administration hospital , our objectives were twofold . the second objective was to determine how ffr values would impact the performance or deferral of revascularization , especially within the gray zone . this was a single - center study that prospectively entered all patients referred for cardiac catheterization for any indication at the north florida / south georgia veterans health system from may 2012 until january 2014 into a database . this database was established to determine the frequency of ffr usage and how ffr values impact revascularization decisions ; therefore , baseline characteristics and clinical outcomes were not recorded . ffr was defined as a whole cardiac cycle pressure - derived index of the maximum achievable blood flow in a coronary artery with a stenosis expressed as a ratio of maximum achievable blood flow if that artery were normal [ 8 , 10 ] . ffr was measured in all intermediate coronary lesions ( 3070% stenosis ) using a coronary pressure guide wire ( volcano corporation ; san diego , ca ) at maximal hyperemia induced by peripherally administrated intravenous adenosine ( 140  g / kg / min for 2  min ) or regadenoson ( 0.4  mg bolus ) at operator discretion . based on the ffr results , the lesions were categorized into three different groups : ffr  >  0.80 ( non - ischemic ) , ffr 0.750.80 ( gray zone ) , and ffr  <  0.75 ( ischemic ) . the decision to defer or proceed with revascularization on the basis of ffr measurement the mean ffr value was 0.79 ( median  =  0.80 , interquartile range 0.640.96 ) . among 211 non - ischemic lesions , revascularization was deferred in 201 ( 95% ) . in the remainder of patients with non - ischemic lesions , referral was placed for coronary artery bypass grafting surgery ( cabg ) for concomitant lesions in eight patients and percutaneous coronary intervention ( pci ) was performed in two cases due to intravascular ultrasound findings . in the gray - zone group ( 73 lesions ) , 35 ( 48% ) lesions were treated with pci , 11 ( 15% ) lesions were referred for cabg , and 27 ( 37% ) lesions were treated medically . in the ischemic group ( 145 lesions ) , 82 ( 57% ) lesions were treated with pci , 41 ( 28% ) lesions were referred for cabg , and 22 ( 15% ) lesions were treated medically . in the gray - zone group , the most common reasons for deferring revascularization included mild angina symptoms , inadequate anti - angina therapy , or high pci complexity . in the ischemic group , the most common reasons for deferring revascularization included small vessel size ( i.e. , < 2.25  mm ) and/or diffuse lesions that markedly increased the risk for restenosis , or high pci complexity . distribution of treatment ( medical , revascularization , or referral for cabg ) in the non - ischemic group ( b ) , gray - zone group ( c ) , and ischemic group ( d ) . cabg coronary artery bypass grafting surgery , pci percutaneous coronary intervention summary for the percentage of lesions in each group . distribution of treatment ( medical , revascularization , or referral for cabg ) in the non - ischemic group ( b ) , gray - zone group ( c ) , and ischemic group ( d ) . in the united states , the average use of ffr has been reported to be as low as 6.1% , with more ffr procedures performed in academic institutions , particularly those with fellowship programs . ffr usage is affected by operator expertise , reimbursement , and the availability of necessary equipment . at our institution , ffr was performed at a higher rate than previously reported ; however , as previously mentioned , the veterans health system is unique since there is no financial incentive to perform revascularization procedures . incorporating ffr in revascularization decisions has been demonstrated to result in fewer pci procedures [ 2 , 1214 ] . our results showed that ffr usage resulted in deferral of revascularization in approximately half of the cases due to non - ischemic lesions . in the gray - zone group , approximately 63% of the lesions either underwent pci or referred for cabg , which is slightly higher than prior studies [ 15 , 16 ] . recent studies had suggested increasing the sensitivity for detecting ischemia ( i.e. , the threshold for revascularization changed from ffr  <  0.75 to < 0.80 ) . we observed that 37% of gray - zone lesions were deferred revascularization which illustrates that in real - life clinical practice there is still adequate room for medical management and clinical judgment for such lesions . revascularization was deferred in the gray - zone group mostly due to mild symptoms and/or inadequate anti - angina therapy . in the ischemic group , this was mostly due to anatomical concerns ( characteristics that made pci high risk or significantly increased the risk for restenosis ) . this study was limited by being an observational study conducted in a single academic center . we did not report any baseline characteristics or clinical outcome data ; however , this information would not be considered particularly germane to the stated objectives of this study . moreover , this information can be found in other reports . meta - analysis of observational studies has documented similar outcomes associated with deferral of non - ischemic left main lesions compared with revascularization of ischemic left main lesions . on the other hand , adverse outcomes are low with deferral of non - ischemic lesions compared with revascularization of ischemic lesions for non - left main lesions . in a single - center practice that does not provide a financial incentive for performing revascularization procedures , ffr usage occurred at a higher frequency than previously reported ( approximately one in four catheterization procedures ) . frequent use of ffr documented lack of ischemia in about half of the intermediate coronary lesions , and thus reduced the need for many revascularization procedures . all procedures followed were in accordance with the ethical standards of the responsible committee on human experimentation ( institutional and national ) and with the helsinki declaration of 1964 , as revised in 2013 . this article is distributed under the terms of the creative commons attribution - noncommercial 4.0 international license ( http://creativecommons.org/licenses/by-nc/4.0/ ) , which permits any noncommercial use , distribution , and reproduction in any medium , provided you give appropriate credit to the original author(s ) and the source , provide a link to the creative commons license , and indicate if changes were made .
introductionfractional flow reserve ( ffr ) is recommended by society guidelines for assessment of the hemodynamic significance of intermediate coronary lesions when non - invasive evidence of myocardial ischemia is unavailable . 
 however , the prevalence of ffr usage in current practice and how ffr values impact revascularization decisions are not well known.methodsat a single - center veterans administration hospital , all subjects referred for coronary angiography for any indication from the period from may 2012 until january 2014 were prospectively entered into a database . 
 ffr was measured in all intermediate coronary lesions ( 3070% stenosis ) . 
 based on the ffr results , the lesions were categorized into 3 different groups : ffr  >  0.80 ( non - ischemic ) , ffr 0.750.80 ( gray zone ) , and ffr  <  0.75 ( ischemic).resultsa total of 1482 cardiac catheterizations were performed during the study period . 
 ffr was performed in 347 ( 23% ) of these procedures . 
 the total numbers of intermediate coronary lesions evaluated with ffr were 429 . 
 the mean ffr value was 0.79 ( median  =  0.80 ; interquartile range 0.640.96 ) . among 211 non - ischemic lesions , 
 revascularization was deferred in 201 ( 95% ) . in the gray - zone group ( 73 lesions ) , 
 35 ( 48% ) lesions were treated with percutaneous coronary intervention ( pci ) , 11 ( 15% ) lesions were referred for coronary artery bypass grafting surgery ( cabg ) , and 27 ( 37% ) lesions were treated medically . in the ischemic group ( 145 lesions ) , 82 ( 57% ) lesions were treated with pci , 41 ( 28% ) lesions were referred for cabg , and 22 ( 15% ) lesions were treated medically.conclusionat a veterans administration hospital , ffr was performed in approximately one out of four total catheterizations . 
 ffr documented lack of ischemia in about half of the intermediate coronary lesions , and thus reduced the need for many revascularization procedures.electronic supplementary materialthe online version of this article ( doi:10.1007/s40119 - 015 - 0051 - 1 ) contains supplementary material , which is available to authorized users .