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Definitions of arterial remodeling in post mortem and Intravascular ultrasound research. G. Pasterkamp Experimental Cardiology, UMC and Interuniversity cardiology Institute of the Netherlands, Utrecht, The Netherlands. Glagov et al. New Engl J Med 1987;316:1371-1375
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Definitions of arterial remodeling in post mortem and Intravascular ultrasound research G. Pasterkamp Experimental Cardiology, UMC and Interuniversity cardiology Institute of the Netherlands, Utrecht, The Netherlands
Glagov et al. New Engl J Med 1987;316:1371-1375 Pasterkamp et al. Circulation 1995;91:1444-1449
Background In international literature, the modes of arterial geometrical remodeling are differentially defined resulting in different prevalence numbers. The current presentation will show and discuss the most widely used definitions
R1 R2 L R3 L = Lesion R1 = most proximal site R2 = proximal reference with normal lumen and least amount of plaque R3 = distal reference with normal lumen and least amount of plaque plaque lumen
Definition 1 Remodeling Index (RI)=VAL/ ( (VAR2+ VAR3)/2) R1 R2 L R3 plaque lumen Expansive remodeling when RI >1.05 Intermediate remodeling when RI >0.95 or < 1.05 Constrictive remodeling when RI <0.95 Smits et al. Heart 1999;82:461-464 von Birgelen et al. J Am Coll Cardiol 2001;37:1864-1870. Schoenhagen et al. Circulation 1999;101:598-603
Definition 2 RI=VAL/ ( (VAR2+ VAR3)/2) R1 R2 L R3 plaque lumen Expansive remodeling when RI >1.0 Constrictive remodeling when RI <1.0 Dangas et al. Circulation 1999;99:3149-3154. Nakamura et al. J Am Coll Cardiol. 2001 Jan;37(1):63-9 Okura et al. J Am Coll Cardiol 2001;37:1031-1035.
Definition 3 R1 R2 L R3 plaque lumen • Expansive remodeling when VA L > VA R2 and VA L > VA R3 • Constrictive remodeling when VA L < VA R2 and VA L < VA R3 • Other values: intermediate remodeling • Nishioka et al. J Am Coll Cardiol 1996;27:1571-1576 • Wexberg et al.J Am Coll Cardiol 2000;36:1860-1869.
Definition 4 Upper limit of normal tapering over 10 mm never exceeds 21% of vessel area reference limit at 0.78 plaque lumen R1 R2 L R3 Expansive/no remodeling when VA L / VA R2 > 0.78 Constrictive remodeling when VA L / VA R2 < 0. 78 Mintz et al Circulation 1997;95:1791-1798.
Definition 5 RI=VAL/ ( VAR1) R1 R2 L R3 plaque lumen Expansive remodeling when RI >1.0 Constrictive remodeling when RI <1.0 Taylor et al. J Am Coll Cardiol 1999 Sep;34(3):760-7
Definition 6RI = VA L / VA R2 (site with least amount of plaque R1 R2 L R3 plaque lumen Expansive remodeling when RI > 1.05 Constrictive remodeling when RI < 0.95 Other values: intermediate remodeling Pasterkamp et al. J Am Coll Cardiol 1995;26:422-428. (Only applied peripheral arteries)
Remodeling definitions lead to large variations in prevalence numbers.
Which definition is best? All studies are cross-sectional The reference is not free of atherosclerotic disease The reference may have been remodeled in either direction We do not know which definition gives us the best estimate of the prevalence of the different remodeling modes.
Which definitions make sense? • Definitions 1-4 share the same receipt, only the tresholds differ. • Definition 5 may be used in casuistic studies, but in larger studies on prevalence this definition should not be used (it will, by definition, approximate the 50% for each remodeling mode) • Definition 6 can only be used in non tapering vessels.
Conclusion • The prevalence of constrictive and expansive remodeling differs widely in literature due to the application of different definitions. • Without serial studies, there is no gold standard for the reference site. • The definition of the remodeling modes merit careful consideration when prevalences are mentioned.