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Objectives: This study sought to compare acute lumen changes and late lumen narrowing during and after excimer laser-assisted balloon angioplasty, measured by quantitative coronary angiography, with the immediate and long-term outcome of balloon angioplasty alone., Background: Although excimer laser coronary angioplasty is used as an adjunct or alternative to balloon angioplasty, limited comparative data exist regarding the immediate and long-term efficacy of excimer laser-assisted balloon angioplasty versus balloon angioplasty alone., Methods: A series of 53 lesions in 47 consecutive patients successfully treated with excimer laser-assisted balloon angioplasty were individually matched after completion of 6-month follow-up angiography with 53 successfully treated balloon angioplasty lesions according to vessel location, preprocedural minimal lumen diameter and reference diameter. Immediate and long-term angiographic results were assessed by an automated lumen contour detection algorithm., Results: Before intervention in the laser and balloon angioplasty groups, respectively, minimal lumen diameter (mean +/- SD) was 0.73 +/- 0.47 and 0.74 +/- 0.46 mm, and reference diameter was 2.71 +/- 0.42 and 2.72 +/- 0.41 mm. Laser angioplasty was followed by adjunctive balloon dilation in 50 lesions. Mean balloon diameter at maximal inflation was similar in both treatment groups (2.61 +/- 0.32 and 2.65 +/- 0.38 mm, respectively), resulting in similar minimal lumen diameters after intervention of 1.77 +/- 0.41 and 1.78 +/- 0.34 mm, respectively. At follow-up angiography, minimal lumen diameter after excimer laser-assisted balloon angioplasty was 1.17 +/- 0.63 mm, and that after balloon angioplasty alone was 1.46 +/- 0.67 mm (p = 0.02). The angiographic restenosis rates at follow-up using the 50% diameter stenosis cutoff criterion were 57% and 34%, respectively (p = 0.02)., Conclusions: Quantitative angiographic analysis of a matched group of 106 successfully treated coronary lesions showed a similar immediate outcome but reduced long-term efficacy of excimer laser-assisted balloon angioplasty compared with that after balloon angioplasty alone.

Objectives: This study was designed to examine whether restenosis is related to the extent or mechanism of lumen improvement and to explore angiographic determinants of optimal atherectomy., Background: Directional atherectomy induces a greater extent of immediate gain and late loss but has not been found to yield a better late angiographic lumen than angioplasty in randomized trials. The difference in lumen renarrowing may be related to either the extent or the mechanism of immediate gain. The design of previous studies has precluded the detection of a device-specific effect on restenosis., Methods: A retrospective analysis was based on matching a prospectively collected series of 80 native coronary arteries successfully treated with atherectomy with a prospectively collected series of 80 native coronary arteries successfully treated with balloon angioplasty. Angiographic analysis was performed in 160 lesions to explore whether a specific device-related effect exists. Multivariate analyses were performed to determine the correlates of minimal lumen diameter at follow-up and late lumen loss and to identify the procedural characteristics for optimal atherectomy., Results: Matching resulted in two comparable groups with equivalent baseline clinical and stenosis characteristics. By study design, atherectomy and angioplasty resulted in similar mean (+/- SD) immediate lumen gain (1.15 +/- 0.44 vs. 1.10 +/- 0.40 mm, p = 0.50). However, lumen loss was more pronounced after atherectomy, and, thus, the minimal lumen diameter at follow-up differed significantly between the two groups (1.78 +/- 0.57 vs. 2.00 +/- 0.56 mm, p = 0.001). Device type was retained in the multivariate analysis as an independent predictor of late minimal lumen diameter and lumen loss. Multivariate analysis identified vessel size and immediate gain as determinants of optimal atherectomy., Conclusions: Restenosis is a consequence not only of the extent of lumen improvement but also of the mechanism of vessel wall injury (debulking vs. dilating). While performing atherectomy, the operator should strive for an optimal procedural result to accommodate an increased intimal hyperplastic response.

Objectives: To characterize predictors of restenosis after successful directional atherectomy, we reviewed the clinical, angiographic and procedural data obtained during 132 consecutive procedures., Methods: Clinical and angiographic follow-up data were obtained in a prospectively collected and consecutive series of 125 patients who underwent 132 atherectomy procedures for de novo (89%) or restenotic (11%) lesions in native coronary arteries. Restenosis was assessed clinically and by quantitative coronary angiography. A dual approach to data analysis was taken to gain insight into factors affecting the clinical outcome and vessel wall healing response. Therefore, multivariate analysis was performed to 1) determine the correlates of residual lumen diameter at follow-up (angiographic outcome), and 2) characterize the determinants of the late lumen loss (renarrowing process)., Results: Clinical and angiographic follow-up data after successful atherectomy were obtained in 100% and 95%, respectively. Atherectomy achieved an acute lumen gain of 1.28 +/- 0.48 mm (mean +/- SD), resulting in a minimal lumen diameter of 2.44 +/- 0.47 mm. At follow-up, the minimal lumen diameter decreased to 1.78 +/- 0.64 mm. The angiographic restenosis rate was 28% if the traditional 50% stenosis cutoff criterion was applied. Larger vessel size and postatherectomy minimal lumen diameter and right coronary or left circumflex artery lesions were independent predictors of a larger minimal lumen diameter (angiographic outcome). Lumen loss during follow-up (renarrowing process) was independently predicted by relative lumen gain and preprocedural minimal lumen diameter., Conclusions: In analyzing the long-term results of new interventional techniques such as directional atherectomy, the late lumen loss during follow-up (renarrowing process), which is characterized by the vessel wall healing response after an intervention, should be considered together with the residual lumen diameter at follow-up (clinical outcome). It is clear that whereas improved clinical outcome is associated with larger vessel size and postprocedural lumen diameter and non-left anterior descending artery location, greater relative gain at intervention is predictive of more extensive lumen renarrowing.

Objectives: The purpose of this study was to examine the proliferative capacity and extracellular matrix synthesis of human coronary plaque cells in vitro., Background: Common to both primary atherosclerosis and restenosis are vascular smooth muscle cell proliferation and production of extracellular matrix proteins. The applicability to humans of experimental animal models of these processes has been questioned., Methods: Primary atherosclerotic and restenotic lesions were excised by percutaneous directional coronary atherectomy in 93 patients. Smooth muscle cells were cultivated by an explant technique and identified by their morphology in culture, ultrastructural features under electron microscopy and immunostaining using monoclonal antibodies to smooth muscle cell alpha-actin. Proliferation in secondary culture was assessed with growth curves and the synthesis of collagen and sulfated glycosaminoglycans by the incorporation of 3H-proline and 35S-sulfate, respectively. These studies were also performed in cells derived from human umbilical artery media., Results: Success rates for primary (45%) and secondary (12%) culture of coronary cells were not influenced by clinical variables or lesion category. Primary culture success was improved by the presence of organized thrombus in the plaque and in relation to increased maximal cell density of the atherectomy specimen. Restenotic cells displayed more rapid growth than did cells of primary atherosclerotic origin, which grew in a manner similar to that of umbilical artery cells. Mean calculated population-doubling times for the three cell groups were 52 h (95% confidence interval [CI] 48 to 58 h), 71 h (95% CI 62 to 83 h) and 74 h (95% CI 65 to 84 h), respectively. Restenotic and primary atherosclerotic cells did not differ in the synthesis of collagen ([mean +/- SEM] 0.034 +/- 0.004 vs. 0.033 +/- 0.004 nmol isotope.microgram protein-1, p = NS) or sulfated glycosaminoglycans (11.47 +/- 1.07 vs. 15.37 +/- 3.10 nmol isotope.microgram protein-1, p = NS), but the coronary cells synthesized significantly more collagen and sulfated glycosaminoglycans than did umbilical artery cells (0.019 +/- 0.004 and 5.43 +/- 1.00 nmol isotope.microgram protein-1, respectively, both p < 0.05)., Conclusions: These data indicate that increased smooth muscle cell proliferation contributes to coronary restenosis in humans and support the concept that the extracellular matrix synthesis of adult smooth muscle cells is important to lesion formation.

Objectives: Late lumen narrowing after directional coronary atherectomy was assessed by quantitative coronary angiography and compared with that after balloon angioplasty., Background: Directional coronary atherectomy has been introduced as an alternative technique for balloon angioplasty and may reduce the incidence of restenosis., Methods: A prospectively collected consecutive series of 87 native coronary artery lesions successfully treated with atherectomy were matched with 87 coronary artery lesions selected from a consecutive series of lesions that had been successfully dilated by balloon angioplasty. Late angiographic analysis was performed in 158 lesions. The net gain index represents the ultimate gain in minimal lumen diameter at follow-up study, normalized for the vessel size. This index is the result of the relative gain attained during the procedure (the ratio of the change in minimal lumen diameter and reference diameter) and the relative loss observed during the follow-up period (the ratio of the change in minimal lumen diameter during the follow-up period and the reference diameter)., Results: Matching for clinical and angiographic variables resulted in two comparable groups with similar baseline stenosis characteristics. Atherectomy resulted in a more pronounced increase in minimal lumen diameter than did balloon angioplasty (mean +/- SD 1.17 +/- 0.29 to 2.44 +/- 0.42 mm vs. 1.21 +/- 0.38 to 2.00 +/- 0.36 mm, p < 0.001). However, this favorable immediate result was subsequently lost during late angiographic follow-up, so that the minimal lumen diameter at follow-up and the net gain index did not differ significantly between the two groups (1.76 +/- 0.62 vs. 1.77 +/- 0.59 mm, p = 0.93, and 0.18 +/- 0.19 vs. 0.17 +/- 0.17, p = 0.70). Consequently, the relative gain and relative loss were higher in the atherectomy group. For both techniques, the relative gain was linearly related to the relative loss but the slope of the regression line was steeper for atherectomy, suggesting that the relative loss in the atherectomy group is proportionally even larger for a given relative gain compared with that in the angioplasty group., Conclusions: In matched groups of patients, atherectomy induces a greater initial gain in minimal lumen diameter than does balloon angioplasty. However, the vascular wall injury induced by the device is of a different nature (debulking vs. dilating) that leads to more relative loss over the follow-up period in the atherectomy group.

Objectives: The safety and long-term results of directional coronary atherectomy in stented coronary arteries were determined. In addition, tissue studies were performed to characterize the development of restenosis., Methods: Directional coronary atherectomy was performed in restenosed stents in nine patients (10 procedures) 82 to 1,179 days after stenting. The tissue was assessed for histologic features of restenosis, smooth muscle cell phenotype, markers of cell proliferation and cell density. A control (no stenting) group consisted of 13 patients treated with directional coronary atherectomy for restenosis 14 to 597 days after coronary angioplasty, directional coronary atherectomy or laser intervention., Results: Directional coronary atherectomy procedures within the stent were technically successful with results similar to those of the initial stenting procedure (2.31 +/- 0.38 vs. 2.44 +/- 0.35 mm). Of five patients with angiographic follow-up, three had restenosis requiring reintervention (surgery in two and repeat atherectomy followed by laser angioplasty in one). Intimal hyperplasia was identified in 80% of specimens after stenting and in 77% after coronary angioplasty or atherectomy. In three patients with stenting, 70% to 76% of the intimal cells showed morphologic features of a contractile phenotype by electron microscopy 47 to 185 days after coronary intervention. Evidence of ongoing proliferation (proliferating cell nuclear antigen antibody studies) was absent in all specimens studied. Although wide individual variability was present in the maximal cell density of the intimal hyperplasia, there was a trend toward a reduction in cell density over time., Conclusions: Although atherectomy is feasible for the treatment of restenosis in stented coronary arteries and initial results are excellent, recurrence of restenosis is common. Intimal hyperplasia is a nonspecific response to injury regardless of the device used and accounts for about 80% of cases of restenosis. Smooth muscle cell proliferation and phenotypic modulation toward a contractile phenotype are early events and largely completed by the time of clinical presentation of restenosis. Restenotic lesions may be predominantly cellular, matrix or a combination at a particular time after a coronary procedure.