Randomized trial of 90Sr/90Y beta-radiation versus placebo control for treatment of in-stent restenosis.

BACKGROUND: After conventional treatment of in-stent restenosis, the incidence of recurrent clinical restenosis may approach 40%. We report the first multicenter, blinded, and randomized trial of intracoronary radiation with the use of a 90Sr/90Y beta-source for the treatment of in-stent restenosis. METHODS AND RESULTS: After successful catheter-based treatment of in-stent restenosis, 476 patients were randomly assigned to receive an intracoronary catheter containing either 90Sr/90Y (n=244) or placebo (n=232) sources. The prescribed dose 2 mm from the center of the source was 18.4 Gy for vessels between 2.70 and 3.35 mm in diameter and 23.0 Gy for vessels between 3.36 and 4.0 mm. The primary end point, ie, clinically driven target-vessel revascularization by 8 months, was observed in 56 (26.8%) of the patients assigned to placebo and 39 (17.0%) of the patients assigned to radiation (P=0.015). The incidence of the composite including death, myocardial infarction, and target-vessel revascularization was observed in 60 (28.7%) of the patients assigned to placebo and 44 (19.1%) of the patients assigned to radiation (P=0.024). Binary 8-month angiographic restenosis (> or =50% diameter stenosis) within the entire segment treated with radiation was reduced from 45.2% in the placebo-treated patients to 28.8% in the 90Sr/90Y-treated patients (P=0.001). Stent thromboses occurred in 1 patient assigned to placebo <24 hours after the procedure and in 1 patient assigned to 90Sr/90Y at day 244. CONCLUSIONS: The results of this study demonstrated that beta-radiation using 90Sr/90Y is both safe and effective for preventing recurrence in patients with in-stent restenosis.

Five-year clinical follow-up after intracoronary radiation: results of a randomized clinical trial.

BACKGROUND: Several clinical trials indicate that intracoronary radiation is safe and effective for treatment of restenotic coronary arteries. We previously reported 6-month and 3-year clinical and angiographic follow-up demonstrating significant decreases in target lesion revascularization (TLR) and angiographic restenosis after gamma radiation of restenotic lesions. The objective of this study was to document the clinical outcome 5 years after treatment of restenotic coronary arteries with catheter-based iridium-192 (192Ir). METHODS AND RESULTS: A double-blind, randomized trail compared 192Ir to placebo sources in patients with restenosis after coronary angioplasty. Over a 9-month period, 55 patients were enrolled; 26 were randomized to 192Ir and 29 to placebo. At 5-year follow-up, TLR was significantly lower in the 192Ir group (23.1% versus 48.3%; P=0.05). There were 2 TLRs between years 3 and 5 in patients in the 192Ir group and none in patients in the placebo group. The 5-year event-free survival rate (freedom from death, myocardial infarction, or TLR) was greater in 192Ir-treated patients (61.5% versus 34.5%; P=0.02). CONCLUSIONS: Despite apparent mitigation of efficacy over time, there remains a significant reduction in TLR at 5 years and an improvement in event-free survival in patients treated with intracoronary 192Ir. The early clinical benefits after intracoronary gamma radiation with 192Ir seem durable at 5-year clinical follow-up.

Clinical and angiographic outcomes after use of 90Strontium/90Yttrium beta radiation for the treatment of in-stent restenosis: results from the Stents and Radiation Therapy 40 (START 40) registry.

PURPOSE: To evaluate the safety and efficacy of a 40-mm 90Strontium/90Yttrium source train in the management of in-stent restenosis within native coronary arteries. MATERIALS AND METHODS: This multicenter, prospective registry was designed to compare the results of patients with in-stent restenosis treated with a 40-mm source train to the placebo arm of the previously reported randomized Stents and Radiation Trial (START). All patients entered in the registry were treated with repeat balloon angioplasty followed by intravascular brachytherapy. Radiation dose was prescribed based on vessel size. 18 Gy was delivered at 2 mm for vessel diameters between 2.75 and 3.35 mm, and 23 Gy was used for vessels between 3.36 and 4.0 mm. The efficacy endpoints for the START 40 registry included a reduction in the target lesion revascularization (TLR) rate, target vessel revascularization rates, and target vessel failure (TVF) at 8 months. Secondary angiographic efficacy endpoints were binary restenosis at 8 months, in-stent minimum luminal diameter (MLD), and late loss. The safety endpoints included major adverse cardiac events as well as late aneurysm formation. The registry was designed to allow a statistically valid comparison of these results to the placebo group of the START 30 trial. Quantitative angiographic analysis was performed on the 8-month follow-up examination. Rates of restenosis were evaluated for various segments of the treated vessel. A separate analysis was performed to evaluate the relationship between vessel injury length and the radiated segment. RESULTS: A total of 207 patients were entered into the START 40 registry. The postprocedure angiographic results, including the postprocedure MLD and percent diameter stenosis, were similar between the START 40 patients and the placebo group from the START trial in the stented segment of the treated vessel. Eight-month angiographic follow-up was available on 150 patients from the registry. The TLR rate was significantly reduced when compared to the placebo group (11% vs. 22.4% respectively, p = 0.008). A similar reduction was seen in terms of target vessel revascularization (15.9% vs. 24.1%, p = 0.03). The 8-month MLD was found to be significantly larger in the START 40 patients (1.85 mm vs. 1.47 mm, p < 0.0001). The difference seen in the clinical endpoint of TVF (19.3% vs. 25.9%) did not reach statistical significance (p = 0.1). Analysis of the procedural angiograms revealed mismatch between the length of vessel injured and the location of the 90% isodose in 46% of the treated cases. Angiographic analysis revealed that geographic miss was associated with a higher rate of binary restenosis (32% vs. 18% p = 0.04) in the analysis segment. CONCLUSIONS: This multicenter registry demonstrates the safety and efficacy of a 40-mm 90Strontium/90Yttrium source train in the management of patients with in-stent restenosis. Restenosis rates were lowered with the use of this longer source train when compared to the placebo arm of the START trial for lesions with a maximum vessel injury length of 20 mm. Angiographic analysis identified the importance of the accurate delineation of injury length and correct source positioning. These results support the continued use of beta radiation for the treatment of this disease process.