Beta Radiation to reduce In-stent resTEnosis II - BRITE II

Description:

The goal of the Beta Radiation to reduce In-stent resTEnosis II (BRITE II) trial was to determine the safety and effectiveness of the RDX Coronary Radiation Delivery System for treatment of in-stent restenosis.

Hypothesis:

The RDX radiation balloon is a safe and effective method to treat in-stent restenosis.

Study Design

Study Design:

Patients Enrolled: 422
Mean Follow Up: 9 months
Mean Patient Age: Mean age 62 years
Female: 36

Patient Populations:

In-stent restenotic lesions in native coronaries, lesion length <45 mm, reference vessel diameter 2.4-3.8 mm, stable or unstable angina or positive functional test, and successful PCI procedure.

Exclusions:

Acute MI <72 hours, ejection fraction <25%, cerebrovascular accident or transient ischemic attack <6 months, and contraindication to ASA or clopidogrel.

Primary Endpoints:

Nine-month TVR and nine-month MACE (death/MI/TVR/CABG).

Secondary Endpoints:

Angiographic restenosis.

Drug/Procedures Used:

Patients with in-stent restenosis were randomized to percutaneous transluminal coronary angioplasty (PTCA) and elective stenting with RDX radiation balloon (n=321) versus placebo (n=102). Repeat angiography was performed at six months. The RDX Radiation Delivery System is a "deployable balloon" source with the radioisotope 32P integrated into the balloon material at a dose of 20 Gy at 1 mm from the source.

Concomitant Medications:

Acetyl salicylic acid (ASA; 325 mg/day) and antiplatelet (75 mg/day) x six months (12 months if new stent is used).

Principal Findings:

The radiation catheter was successfully delivered to all but 14 (3%) lesions and failed to deliver the radiation, due to device malfunction in an additional two patients (1%). The mean prescribed dose was 19.7 ± 0.4 Gy at 1 mm from the inflated source surface, and the average delivery dwell time was 8.3 ± 0.87 minutes. PTCA was the most frequently used procedure in 68% of patients.

Major adverse cardiac events (MACE) at nine months were significantly lower in the beta-radiation arm compared with placebo (27% vs. 45%, p=0.02), driven by a reduction in target vessel revascularization (TVR; 25% vs. 43%, p=0.02). There was no difference in death (1% vs. 2%, p=NS) or myocardial infarction (MI; p=NS). Restenosis at nine months was lower with beta-radiation in the stent segment (10.9% vs. 46.1%, p<0.001) and in the analysis segment (29% vs. 48%, p<0.001).

Interpretation:

Among patients with in-stent restenosis, treatment with the RDX beta radiation balloon following percutaneous coronary intervention (PCI) was associated with a reduction in the primary end point of MACE at nine months, and with a reduction in restenosis at nine-month angiographic follow-up. The reduction in MACE was driven almost exclusively by a reduction in TVR, with no difference observed in death or MI. Despite the positive results of the BRITE II trial, the presenter indicated the RDX system is not likely to reach the market, due to commercial consideration.

The present study was performed only on native coronary lesions. No data with beta radiation for restenosis in saphenous vein grafts have been performed to date. Use of beta-radiation rather than gamma-radiation may reduce the exposure time from 20-30 minutes to 3-5 minutes, reducing the risk to both the catheterization laboratory staff, as well as the nontarget tissue of the patient.

References:

Presented at Late-Breaking Clinical Trials, ACC 2003.

Clinical Topics: Invasive Cardiovascular Angiography and Intervention

Keywords: Myocardial Infarction, Beta Particles, Radioisotopes, Saphenous Vein, Catheterization, Angioplasty, Balloon, Coronary, Stents, Percutaneous Coronary Intervention


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