Histopathology of coronary lesions with early loss of minimal luminal diameter after successful percutaneous transluminal coronary angioplasty: Is thrombus a significant contributor?

Background: Early loss of minimal luminal diameter of >0.3 mm after successful percutaneous transluminal coronary angioplasty (PTCA) is associated with a higher incidence of restenosis. The underlying mechanism of this early loss is unknown and thrombus may be a contributing factor. Methods: We performed a prospective study using quantitative computerized 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 (37%) of 24 coronary specimens. Segmental areas (mm²) and percentage of total area were distributed as follows: sclerotic tissue, 4.07 ± 0.7 mm² (63% ± 6%); fibrocellular tissue, 0.97 ± 0.27 mm² (16% ± 4%); hypercellular tissue, 0.99 ± 0.29 mm² (12% ± 3%); atheromatous gruel, 0.18 ± 0.07 mm² (3% ± 0.1%); and thrombus, 0.24 ± 0.15 mm² (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 analysis did not identify any histologic predictors of relative early loss 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.