Braquiterapia intracoronariana. Tratamento da reestenose intra-stent com o sistema Beta-Cath: experiência inicial na América Latina / Intracoronary brachytherapy. Treatment of in-stent restenosis with the Beta-Cath system: initial experience in Latin America

OBJETIVO: Avaliar a segurança e eficácia da braquiterapia intracoronariana usando o sistema Beta-CathTM na prevenção da recorrência de restenose intra-stent (RIS), por meio da análise dos resultados clínicos, angiográficos e pelo ultra-som intracoronariano (USIC). MÉTODO: Foram submetidos à angioplastia com cateter-balão, seguida de beta-radiação intracoronariana com o sistema Beta-CathTM (90Sr/Y) 30 pacientes com RIS em artérias coronárias nativas e, posteriormente, avaliados. RESULTADOS: Incluíram-se lesões reestenóticas complexas (77 por cento do tipo difuso-proliferativo) com extensão elevada (18,66±4,15 mm). O sucesso da braquiterapia foi de 100 por cento. A dose média utilizada foi de 20,7±2,3 Gy, liberada em um período médio de 3,8±2,1 min. No seguimento tardio, o diâmetro luminal mínimo (DLM) intra-stent diminuiu discretamente (1,98±0,30mm para 1,84±0,39 aos 6 meses, p=0,13), com uma perda tardia de 0,14±0,18 mm. O DLM intra-segmentar foi significativamente menor do que o intra-stent (1,55±0,40mm vs.1,84±0,39mm, p=0,008), associando-se à perda tardia (0,40±0,29mm vs. 0,14±0,18mm; p=0,0001). No USIC, observou-se discreto incremento do tecido neointimal em 6,8±14,3 mm aos 6 meses (p=0,19) e a percentagem de obstrução volumétrica aumentou em 4,7±7,5 por cento. A reestenose binária e a revascularização do vaso-alvo recorreram em 17 por cento dos casos; houve 1 caso (3 por cento) de oclusão tardia, associada a infarto do miocárdio. A sobrevida livre de eventos foi de 80 por cento. CONCLUSAO: O manejo da reestenose intra-stent com a beta-radiação intracoronariana mostrou-se procedimento seguro e eficaz, com alta taxa de sucesso imediato, representando uma opção terapêutica para a inibição da hiperplasia neointimal.

A Novel Method of Brachytherapy Using Local Delivery of (99m) Tc-HMPAO for Coronary Stent Restenosis

BACKGROUND: Restenosis after percutaneous coronary intervention (PCI) is a matter that still remains to be resolved. Herein, the inhibitory effect of locally delivered (99m) Tc-HMPAO (hexamethyl propylene amine oxime) on neointimal hyperplasia after coronary stenting was examined in a pocine model, and its safety and efficacy observed in patients with coronary stent restenosis. METHODS: After a stent overdilation injury, local radioisotope delivery using (99m) Tc-HMPAO was applied to one coronary artery (Group I) and control therapy to another (Group II) in each of 10 pigs. Follow-up coronary angiogram (CAG) and histopathologic assessment were performed 4 weeks after stenting. Eleven patients (10 males and one female, 62.4 +/- 5.7 years of age) underwent local administration of 30 mCi/ 2 mL (99m) Tc-HMPAO shortly after PCI, via a Dispatch CatheterTM, followed by a whole body scan to evaluate the distribution of the (99m) Tc-HMPAO, as well as a thallium-201 (Tl-201) myocardial scan to evaluate myocardial perfusion. The major adverse cardiac events (MACE) were assessed during a one-year clinical follow-up. RESULTS: On histopathological analysis, the neointimal areas were 1.2 +/- 0.6 and 2.7 +/- 0.4 mm2 (p=0.002), and the histopathological areas of stenosis were 27.16.3 and 53.4 +/- 5.2% in Groups I and II (p=0.001), respectively. In the clinical study, there was no in-hospital MACE. On a quantitative coronary angiographic analysis, the minimal luminal diameter was increased from 0.4 +/- 0.3 to 2.9 +/- 0.2 mm, and diameter stenosis decreased from 84.2 +/- 9.5 to 16.3 +/- 11.0% following PCI. Follow-up CAG was performed in 9 cases (81.8%) and restenosis occurred in 2 (22.2%). On a follow-up CAG, the minimal luminal diameter, diameter stenosis rate, lumen loss and loss index were 2.0 +/- 0.8 mm, 27.7 +/- 2.9%, 0.7 +/- 0.7 mm and 0.2 +/- 0.3, respectively. During the one-year clinical follow-up there were no cases of death or acute MI, but two cases of target vessel revascularization (18.2%). CONCLUSION: Local delivery of (99m) Tc-HMPAO, a novel radiotherapy, can be used safely and effectively for coronary stent restenosis.