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The management of diabetic patients with restenosis after percutaneous coronary intervention remains a significant challenge. Diabetic patients remain at significant risk of restenosis despite stent implantation. This retrospective analysis was performed to determine the extent to which vascular brachytherapy improves late clinical and angiographic outcomes in diabetic patients compared to conventional therapy and compared to patients' nondiabetic counterparts.Pooled data from two studies (START [Stents and Radiation Trial] and START-40 trials) of patients (204 diabetic, 477 nondiabetic) receiving vascular brachytherapy (VBT) with a (90)Sr/(90)Y source after conventional percutaneous coronary intervention for in-stent restenosis comprise the study population. The radiation delivery system used in both studies was the Beta-Cath system. The prescribed dose at 2 mm from the centerline of the source axis was 18.4 Gy or 23 Gy, depending on vessel diameter. The reference vessel diameter, minimal lumen diameter, and percent diameter stenosis were measured before the intervention, at the conclusion of the procedure, and at the 8-month follow-up examination. The Breslow-Day test was used to formally assess the similarity of treatment effect between diabetic and nondiabetic patients.Target lesion and target vessel revascularization rates and angiographic restenosis rates in diabetic and nondiabetic patients treated with beta radiation or placebo were analyzed. Diabetic patients were more likely to have longer and more complex coronary lesions. In-hospital outcomes in diabetic and nondiabetic patients were similar, irrespective of treatment status. At 8 months, patients treated with beta radiation exhibited less target lesion revascularization (diabetic: 10.9% vs. 22.7%, p = 0.02; nondiabetic: 12.8% vs. 22.3%, p = 0.007) and less target vessel revascularization (diabetic: 14.7% vs. 25.3%, p = 0.06; nondiabetic: 16.6% vs. 23.6%, p = 0.06) compared to placebo. In-stent binary angiographic restenosis was lower in irradiated patients (diabetic: 19.4% vs. 37.3% for placebo, p = 0.01; nondiabetic: 12.9% vs. 43% for placebo, p0.001). However, restenosis beyond the stent site reduced the impact of VBT, regardless of diabetic status. The magnitude of the treatment effect for target lesion and target vessel revascularization rates was similar between diabetic and nondiabetic patients.Previously published institutional experiences have suggested that diabetic patients benefit from the use of VBT in the management of in-stent restenosis. This analysis now provides direct evidence to support the role of beta radiation VBT in this patient population. Diabetic patients undergoing this therapy are just as likely to benefit from it as their nondiabetic counterparts.

Purpose: In this study, the effect of barotrauma due to stent deployment is investigated for several commonly used commercial stents used in endovascular brachytherapy for restenosis prevention. Methods and Materials: Restenosis due to intimal hyperplasia can occur anywhere along the clinical target volume, which is defined as the length of vessel receiving intervention or injury. The injury may be due to angioplasty, atherectomy (tissue removing), stenting, and stent deployment. Manufacturer specifications for several commonly used stents were reviewed and the results were tabulated. Results: The barotrauma length of stents reviewed in this study ranges from 0.5 to 2.5 mm; the average was 1.7 mm. Conclusions: By considering specific barotrauma into the treatment length, one can provide adequate treatment margins to minimize edge failure or to avoid "geographic miss," which may improve the efficacy of endovascular brachytherapy.

This year is the 100th anniversary of the use of ionizing radiation to treat disease. Since the turn of the century, many benign and malignant diseases have been treated with radiation therapy (RT). Through the decades, however, the application of RT in the treatment of benign diseases has largely disappeared-supplanted by other medical or surgical therapies. RT has most recently been committed to the treatment of malignancies to such a degree that the specialty was renamed radiation oncology. However, a continued. though very limited, role for RT has persisted in the treatment of certain benign hyperplastic disorders. RT significantly inhibits excessive fibroblast activity. Judicious clinical use of low-dose RT is highly effective in inhibiting such benign conditions as conjunctival pterygia. keloid scars. and aggressive fibromatosis. Excessive bone formation by the osteoblast, a derivative of the fibroblast. is successfully inhibited by low-dose RT and thereby inhibits heterotopic ossification. Although such benign hyperplasia disorders are significant clinical entities, the main thrust of RT continues to be the treatment of malignancies. With the coming millennium, a new therapeutic application of RT in benign disease promises to open new vistas previously unimagined. Studies have just begun in using RT to prevent vascular restenosis. RT may provide a powerful tool to solve what has become a vexing problem in vascular disease. In this review, we shall discuss early preclinical evidence that endovascular brachytherapy may inhibit coronary artery restenosis. We shall also introduce and describe the Scripps Clinic’s ongoing trial of endovascular RT in the prevention of coronary artery restenosis. The Scripps Coronary Radiation to Inhibit Proliferation Post Stenting trial (SCRIPPS) is the first attempt to use catheter-based intracoronary ionizing radiation in a prospective double-blinded randomized study. The study’s objective is to determine the initial safety and efficacy in reversing and preventing coronary artery restenosis by adding lowdose RT to today’s optima1 conventional cardiovascular therapy. This review will hopefully also provide a basis to understand the rationale and some of the potential benefits of applying radiation in the treatment of coronary artery restenosis.

In the Scripps Coronary Radiation to Inhibit Proliferation Poststenting (SCRIPPS) Trial, 192Ir significantly reduced angiographic, ultrasonographic, and clinical endpoints of restenosis. The objective of this analysis was to quantitate the impact of patient, lesion and technical characteristics on late angiographic outcome.Patients with restenotic, stented coronary lesions were randomized to receive either 192Ir or placebo sources. Late luminal loss and loss index were calculated for several patient subgroups, including patients with diabetes, in-stent restenosis, multiple previous percutaneous transluminal coronary angioplasty (PTCA) procedures, longer lesion lengths, saphenous vein grafts, small vessel diameters, and minimum dose exposures8.00 Gy. Two-factor analysis of variance was used to test for an interaction between patient characteristics and treatment effect.In the treated group, late loss was particularly low in patients with diabetes (0.19 mm), in-stent restenosis (0.17 mm), reference vessel diameters3.0 mm (0.07 mm), and patients who received a minimum radiation dose to the entire adventitial border of at least 8.00 Gy. The loss index in each of these subgroups was similarly low at -0.02, 0.03, -0.02, and 0.03, respectively. By 2-factor analysis of variance, a significant interaction between subgroup characteristic and treatment effect (late loss) was found in patients with in-stent restenosis (p = 0.035), and patients receiving a minimum dose of 8.00 Gy to the adventitial border (p = 0.009).In this pilot study, patient characteristics associated with a more aggressive proliferative response to injury appeared to confer an enhanced response to radiotherapy. Furthermore, a dose threshold response to 192Ir was found with an enhanced response occurring when the entire circumference of the adventitial border was exposed to at least 8.00 Gy.