Inhibition of Restenosis With β-Emitting Radiotherapy

Abstract

Background-Intracoronary ␥-and ␤-radiation have reduced restenosis in animal models. In the clinical setting, the effectiveness of ␤-emitters has not been studied in a broad spectrum of patients, particularly those receiving stents. Methods and Results-A prospective, randomized, sham-controlled study of intracoronary radiotherapy with the ␤-emitting 32 P source wire, using a centering catheter and automated source delivery unit, was conducted. A total of 105 patients with de novo (70%) or restenotic (30%) lesions who were treated by stenting (61%) or balloon angioplasty (39%) received 0 (control), 16, 20, or 24 Gy to a depth of 1 mm in the artery wall. Angiography at 6 months showed a target site late loss index of 11Ϯ36% in radiotherapy patients versus 55Ϯ30% in controls (PϽ0.0001). A low late loss index was seen in stented and balloon-treated patients and was similar across the 16, 20, and 24 Gy radiotherapy groups. Restenosis (Ն50%) rates were significantly lower in radiotherapy patients at the target site (8% versus 39%; Pϭ0.012) and at target site plus adjacent segments (22% versus 50%; Pϭ0.018). Target lesion revascularization was needed in 5 radiotherapy patients (6%) and 6 controls (24%; PϽ0.05). Stenosis adjacent to the target site and late thrombotic events reduced the overall clinical benefit of radiotherapy. Conclusions-␤-radiotherapy with a centered 32 P source is safe and highly effective in inhibiting restenosis at the target site after stent or balloon angioplasty. However, minimizing edge narrowing and late thrombotic events must be accomplished to maximize the clinical benefit of this modality. (Circulation. 2000;102:951-958.)

Evolução da Intervenção Percutânea para o Tratamento da Doença Coronária Multiarterial

“…Já o estudo PREVENT (Inhibition of Restenosis With b-Emitting Radiotherapy) comparou a radiação beta com o placebo em lesões de novo (70%) e reestenóticas (30%), com taxa de reestenose em seis meses de 22% versus 50% (p=0,018), enquanto o estudo Beta WRIST (Intracoronary b-Radiation Therapy Inhibits Recurrence of In-Stent Restenosis) analisou os resultados da radiação beta somente em lesões reestenóticas com taxa de reestenose em seis meses de 34% versus 71% no grupo placebo (p=0,001) 41,42 .…”

“…Contudo, deve-se aguardar os resultados tardios dos estudos com radiação beta e gama em andamento para o melhor esclarecimento dos resultados a longo prazo da braquiterapia. Outra questão igualmente importante é a trombose tardia, ocorrida em 5,3-10,0% dos pacientes tratados com radiação [39][40][41][42] , especialmente após a interrupção da ticlopidina ou do clopidogrel, o que indica a necessidade de se reavaliar a duração do tratamento com antiagregantes plaquetários nos pacientes submetidos a braquiterapia.…”

Simple New Method for Making a Rat Carotid Artery Post-angioplasty Stenosis Model -Technical Note-

“…4) Various methods for the prevention of restenosis after coronary PTA/stenting have been reported, such as brachytherapy with beta or gamma beams 11,15,16) and drug-eluting stents. 2,3) However, ongoing clinical trials have not resolved the problem of restenosis of the coronary artery.…”

Beta irradiation: new uses for an old treatment: a review

“…Placement of 32 P wires markedly reduced subsequent restenosis rates in a recently reported randomised controlled trial, and extensive investigation continues in this field. 1,2 In ophthalmology, the role of both external beam radiation and brachytherapy in the management of age-related macular degeneration (ARMD) and the role of beta radiation in trabeculectomy are currently under evaluation. It is therefore appropriate to revisit the role of beta radiation in ophthalmology.…”