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(Circulation. 1999;100:2491.)
© 1999 American Heart Association, Inc.

Clinical Investigation and Reports

Abnormal Coronary Flow Velocity Reserve After Coronary Artery Stenting in Patients

Role of Relative Coronary Reserve to Assess Potential Mechanisms

Morton J. Kern, MD; Sanjeev Puri, MD; Richard G. Bach, MD; Thomas J. Donohue, MD; Patrick Dupouy, MD; Eugene A. Caracciolo, MD; W. Randall Craig, MD; Frank Aguirre, MD; Eduardo Aptecar, MD; Thomas L. Wolford, MD; Carol J. Mechem, RN; Jean-Luc Dubois-Rande, MD

From the Department of Internal Medicine, Division of Cardiology, Saint Louis University Health Sciences Center, Mo, and Service D’Explorations Fonctionnelles (P.D., E.A., J.-L.D.-R.), Unite D’Hemodynamique et de Cardiologie Interventionnelle, Henri Mondor University Hospital, University of Paris XII, Creteil, France.

Correspondence to Morton J. Kern, MD, Director, J.G. Mudd Cardiac Catheterization Laboratory, Saint Louis University Health Sciences Center, 3635 Vista Avenue at Grand Blvd, St. Louis, MO 63110. E-mail kernm{at}slu.edu

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.

Methods and 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 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.

Key Words: coronary disease • blood flow • stents • stenosis