240 likes | 343 Views
Radiation for restenosis: the dark side of arteries. hot. Robert S Schwartz MD Professor of Medicine Mayo Clinic Rochester, MN. Figure 1. Stimulation of neointima within an irradiated artery. Figure 2. Minimal neointimal neoplasia post stent placement. External beam radiation.
E N D
Radiation for restenosis:the dark side of arteries hot Robert S Schwartz MDProfessor of MedicineMayo ClinicRochester, MN
Figure 1 Stimulation of neointima within an irradiated artery
Figure 2 Minimal neointimal neoplasia post stent placement
External beam radiation • major US center • 11 patient pilot study • 8 Gy external beam radiation • 11/11 restenosis the restenosis rate was 100%
Radiation injury to blood vessels • capillary injury is greatest • obliteration of capillaries one mechanism of anti-tumor action • thrombosis, rupture, fibrosis • occasionally lymphocytic vasculitis • venous lesions are uncommon
Figure 3 Induction of neointima post external beam radiation
Venezuelan study the late loss is too high 0.44 0.40 0.33 0.32 0.28 0.27 0.26 0.25 Condado LRT MARCATOR BENESTENT HELVETICA CARPORT MERCATOR PARK Figure 4: late loss (millimeters) Condado J, Circulation 1997;96:727
3 questions on radiation • Q: Is arterial radiation feasible? A: “Yes” • Q: Is it safe? A: “We doubt it” • Q: Is it efficacious? A:”We don’t think so” Serruys et al, Circulation 1997;96:709-712
Figure 5 Neointimal hyperplasia at former sites of radiation
PREVENT trial 25.0% 22.2% 9.1% 0.0% P 32 Control Figure 6 Restenosis in the treated segment Raizner et al, PREVENT trial 1998
PREVENT trial 25.0% 22.7% 11.1% 0.0% P 32 Control Figure 7 Restenosis in the adjacent segment Raizner et al, PREVENT trial 1998
PREVENT trial 25.0% 22.7% 22.2% 0.0% P 32 Control Figure 8 Restenosis in the treated and adjacent segments Raizner et al, PREVENT trial 1998
BERT trial • restenosis rate of 17% • 6 patients with an “edge problem” • overall restenosis rate of 25%
Beta emitting stents and restenosis 56.0% (10/18) 50.0% (1/2) 45.0% (5/11) 39.0% (11/28) 0.75-3 uCi 3-6 uCi 6-12 uCi 12-20 uCi Figure 9 Restenosis in the treated and adjacent segments
Figure 10 Cellular neointimal hyperplasia of in-stent restenosis
Figure 11 Neointimal hyperplasia at former sites of radiation
The BRIE trial • European registry, 150 patients • PTCA up to 2 vessels • Beta-Cath system, 90-Sr/Y • 12,14,16 Gy to 2 mm from source • target vessel restenosis 30% • late loss index 13% Serruys, 1999
Figure 12 Human coronary artery thrombus in situ
Figure 13 Old thrombus New thrombus Absence of neointima Multi-layered thrombus in a pig coronary artery
Intracoronary beta radiation P=NS 4 ) 3.16 2 2.84 3 Neointimal 2 area (mm 1 0 control treated Figure 14 Effects of intracoronary beta-radiation after 6 months in stented vessels
SCRIPPS trial 54% 17% control radiated Figure 15 Angiographic restenosis rate
P=NS SCRIPPS trial Figure 16 The SCRIPPS radiated group, a long term analysis
GAMMA-I in-stent measures Figure 17 GAMMA-I 6 month follow-up
Figure 18 EVG Actin Heat injury