title: Abnormal coronary flow velocity reserve after coronary artery stenting in patients: role of relative coronary reserve to assess potential mechanisms.
abstract: BACKGROUND
  Absolute coronary flow velocity reserve (CVR) after stenting may remain abnormal as a result of several different mechanisms. Relative CVR (rCVR=CVR(target)/CVR(reference)) theoretically normalizes for global microcirculatory disturbances and facilitates interpretation of abnormal CVR.
  
  
  RESULTS
  To characterize potential mechanisms of poststent physiology, CVR was measured using a Doppler-tipped angioplasty guidewire in 55 patients before and after angioplasty, after stenting, and in an angiographically normal reference vessel. For the group, the percent diameter stenosis decreased from 75+/-13% to 40+/-18% after angioplasty and to 10+/-9% (all P<0.05) after stent placement. After angioplasty, CVR increased from 1.63+/-0.71 to 1.89+/-0.55 (P<0.05) and after stent placement, to 2.48+/-0.75 (P<0.05 versus pre- and postangioplasty). After angioplasty, rCVR increased from 0.64+/-0.26 to 0.75+/-0.23 and after stent placement to 1.00+/-0.34. In 17 patients with CVR(stent) < or = 2.0, increased basal coronary flow, rather than attenuated hyperemia, was responsible in large part for the lower CVR(stent) compared with patients having CVR(stent) >2.0. In 8 patients with CVR(stent) <2.0, a normal rCVR supported global microvascular disease. The subgroup of 9 patients with CVR(stent) <2.0 and abnormal rCVR (16% of the studied patients) may require a pressure-derived fractional flow reserve to differentiate persistent obstruction from diffuse atherosclerotic disease or microvascular stunning.
  
  
  CONCLUSIONS
  Although a majority of patients after stenting normalize CVR for the individual circulation (ie, normal CVR or normal rCVR), in those with impaired CVR(stent), the analysis of coronary flow dynamics suggests several different physiological mechanisms. Additional assessment may be required to fully characterize the physiological result for such patients to exclude remediable luminal abnormalities.
authors.affiliation: Department of Internal Medicine, Saint Louis University Health Sciences Center, MO 63110, USA. kernm@slu.edu
authors.forename: M J
authors.initials: MJ
authors.lastname: Kern
authors.forename: S
authors.initials: S
authors.lastname: Puri
authors.forename: R G
authors.initials: RG
authors.lastname: Bach
authors.forename: T J
authors.initials: TJ
authors.lastname: Donohue
authors.forename: P
authors.initials: P
authors.lastname: Dupouy
authors.forename: E A
authors.initials: EA
authors.lastname: Caracciolo
authors.forename: W R
authors.initials: WR
authors.lastname: Craig
authors.forename: F
authors.initials: F
authors.lastname: Aguirre
authors.forename: E
authors.initials: E
authors.lastname: Aptecar
authors.forename: T L
authors.initials: TL
authors.lastname: Wolford
authors.forename: C J
authors.initials: CJ
authors.lastname: Mechem
authors.forename: J L
authors.initials: JL
authors.lastname: Dubois-Rande
mesh_terms: D000368:Aged; D015906:Angioplasty, Balloon, Coronary; D001783:Blood Flow Velocity; D017023:Coronary Angiography; D003326:Coronary Circulation; D003327:Coronary Disease / Q000503:physiopathology / Q000628:therapy*; D005260:Female; D006801:Humans; D008297:Male; D008833:Microcirculation; D008875:Middle Aged; D012008:Recurrence; D015607:Stents