Primary peripheral arterial stenoses and restenoses excised by transluminal atherectomy: A histopathologic study

Atherectomy is a new therapeutic intervention for the treatment of peripheral arterial disease, and permits the controlled excision and retrieval of portions of stenosing lesions. The gross and light microscopic features of 218 peripheral arterial stenoses resected from 100 patients by atherectomy were studied. One hundred seventy of these lesions were primary stenoses and 48 were restenoses subsequent to prior angioplasty or atherectomy. Microscopically, primary stenoses were composed of atherosclerotic plaque (150 lesions), fibrous intimai thickening (15 lesions) or thrombus alone (5 lesions). Atherosclerotic plaques had a variable morphology and, in one-third of cases, were accompanied by abundant surface thrombus that probably added to the severity of stenosis. Most patients with fibrous intimai thickening or thrombus alone had typical atherosclerotic plaque removed elsewhere from within the same artery.Intimai hyperplasia, with or without underlying residual plaque, was found at 36 sites of restenosis, the remaining 12 consisting of plaque only. Intimai hyperplasia had a distinctive histologic appearance and was due to smooth muscle cell proliferation within a loosely fibrous stroma. Superimposed thrombus may have contributed to arterial narrowing in 25% of hyperplastic and 8% of atherosclerotic restenoses (p = 0.41). Pathologic examination of tissues recovered by peripheral atherectomy is an important adjunct that may provide insight into the efficacy of vascular interventions and the phenomenon of postintervention restenosis

Dedicated Bifurcation Stent for the Treatment of Bifurcation Lesions InvolvingLarge Side Branches: Outcomes From the Tryton Confirmatory Study

Objectives: The aim of this study was to prospectively study and confirm the safety and efficacy of the Tryton Side Branch Stent in the treatment of coronary artery bifurcations involving large side branches (SBs). Background The TRYTON Pivotal randomized controlled trial (RCT) was designed to compare the Tryton stent with standard provisional SB stenting in large vessels. The trial inadvertently enrolled patients with too small SBs ( < 2.25 mm). The overall trial did not meet its primary endpoint, because of an increased rate of periprocedural myocardial infarction in the Tryton stent arm. A post hoc analysis restricted to the intended population showed that the trial would have met its endpoint if only patients with SBs ≥2.25 mm in diameter (by core laboratory quantitative coronary angiography) had been enrolled.MethodsThe Tryton Confirmatory Study was a prospective, single-arm extension of the TRYTON Pivotal RCT that enrolled an additional 133 patients treated with the Tryton Side Branch Stent. It was designed to confirm the results of the post hoc analysis and emphasized the inclusion of appropriately sized SBs. The primary endpoint was noninferiority with regard to periprocedural myocardial infarction (creatine kinase myocardial band 3 times the upper limit of normal) compared with a performance goal based on the TRYTON Pivotal RCT.ResultsAmong the 133 enrolled patients, 132 (99.2%) had SBs ≥2.25 mm. Baseline clinical and angiographic parameters were similar in this study and the RCT. Periprocedural myocardial infarction occurred in 10.5% of patients, which was numerically lower than the provisional group in the TRYTON Pivotal RCT (11.9%). The 95% confidence bounds did not extend beyond the pre-defined performance goal of 17.9%, meeting the noninferiority primary endpoint.ConclusionsThe Tryton Confirmatory Study, in conjunction with the post hoc analysis of the intended population in the TRYTON Pivotal RCT, supports the safety and efficacy of the Tryton Side Branch Stent for treatment of bifurcation lesions involving large SBs