HISTOPATHOLOGY OF CORONARY LESIONS WITH EARLY LOSS OF MINIMAL LUMINALDIAMETER AFTER SUCCESSFUL PERCUTANEOUS TRANSLUMINAL CORONARY ANGIOPLASTY - IS THROMBUS A SIGNIFICANT CONTRIBUTOR

Background Early loss of minimal luminal diameter of >0.3 mm after suc cessful percutaneous transluminal coronary angioplasty (PTCA) is assoc iated with a higher incidence of restenosis. The underlying mechanism of this early loss is unknown and thrombus may be a contributing facto r. Methods We performed a prospective study using quantitative compute rized planimetry on coronary tissue specimens obtained by directional coronary atherectomy of 24 lesions in which early loss occurred 22 +/- 9 minutes after successful PTCA. Results Thrombus was present in 9 (3 7%) of 24 coronary specimens. Segmental areas (mm(2)) and percentage o f total area were distributed as follows: sclerotic tissue, 4.07 +/- 0 .7 mm(2) (63% +/- 6%); fibrocellular tissue, 0.97 +/- 0.27 mm(2) (16% +/- 4%); hypercellular tissue, 0.99 +/- 0.29 mm(2) (12% +/- 3%); ather omatous gruel, 0.18 +/- 0.07 mm(2) (3% +/- 0.1 %); and thrombus, 0.24 +/- 0.15 mm(2) (6% +/- 0.4%). There was no difference in the relative early loss index between lesions with or without thrombus (35% +/- 7% vs 26% +/- 2%, respectively; P = .87). Multiple stepwise regression an alysis did not identify any histologic predictors of relative early lo ss index. Conclusion Histopathologic analysis of coronary lesions with early loss after successful PTCA suggests that thrombus may not play a significant role in this angiographic phenomenon.