Beta Energy Restenosis Trial - 1 - BERT
Beta-radiation for prevention of angiographic restenosis after PTCA.
To test the feasibility, safety, and preliminary efficacy of beta radiation for preventing restenosis after PTCA.
Patients Screened: Not given
Patients Enrolled: 78
Mean Follow Up: 6 months
Mean Patient Age: 57.2
Available for follow-up
Novoste Beta-Cath device.
Patients were randomized to receive 12, 14, or 16 Gy measured 2 mm from the center of the source following balloon angioplasty. Thirteen patients had angioplasty, radiation therapy, and intracoronary stenting, while the remaining 65 patients had angioplasty with radiation therapy alone. The majority of patients had either type B1 (31%) or type B2 (56%) lesions.
The baseline reference diameter was 2.75 ± 0.037mm, with a 72.6 ± 9.19 percent stenosis. The pre-procedure MLD was 0.75 ± 0.26mm, equivalent to a 73.6 ± 9.2 percent stenosis. The post-procedure MLD was 2.05 ± 0.41mm, equivalent to 26.4 ± 12.1 percent stenosis. At six-months follow-up, the MLD was 1.93 ± 0.74mm, or a residual stenosis of 30.2 ± 23.8 percent. The majority of patients were without late loss (1.3mm), with a late loss index of 0.08. Two patients had total occlusions at follow-up, and this was attributed to early thrombotic events.
The dichotomous target lesion restenosis rate (> 50% stenosis) was 17%. The target lesion was revascularized in 11 patients (14.1%). Six patients (7.7%) developed new lesions in the intervention area. In the 13 patients who received rescue stent therapy, the pre- , post-, and follow-up MLDs were 0.72, 2.44, and 2.25mm, respectively. There was little intimal proliferation observed in these patients, with a late loss index of 0.16.
The dose-response relationship was weak, with late loss indices of 0.17, 0.01, and 0.07 for the 12, 14, and 16 Gy dose groups, respectively.
QCA revealed a lower than expected restenosis rate for the BERT population compared to historical controls (17% vs 42% for the lovastatin restenosis trial). There was a trend towards improved results for optimal PTCA (with <30% residual stenosis), for small vessels (with reference diameter < 3mm), for narrow stenoses (with MLD < 2mm) and for higher radiation doses. The investigators speculated that very low-dose radiation may affect re-endothelialization, reducing neoproliferation of intimal tissue, but not affect the adventitial cells, creating an exuberant response at the edges of the treated segment.
Intravascular brachytherapy is a promising approach for restenosis; however, the details of technique, dosing, and long-term outcome remain to be elucidated.
1. Circulation 1998;98(Suppl I):651 Preliminary results
Keywords: Beta Particles, Follow-Up Studies, Lovastatin, Coronary Restenosis, Angioplasty, Balloon, Coronary, Brachytherapy, Stents
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