Abstract 12082: Radiofrequency Ablation of the Atherosclerotic Plaque: A Safety and Feasibility Study in an Atherosclerotic Rabbit Model
Introduction: Angiogenesis from the vasa vasorum plays a key role in atheroprogression and plaque vulnerability. Immature neovessels are prone to leakage, hence facilitating additional lipid and inflammatory cell accumulation and increasing intraplaque hemorrhage risk.
Hypothesis: Heat-generating radiofrequency ablation (RFA) safely reduces vasa vasorum, decreases inflammatory cell influx and stabilizes the plaque.
Methods: Thirteen New-Zealand White rabbits on a 0.5% cholesterol-enriched diet were subjected to balloon denudation of the infrarenal aorta. After 13 weeks, either the proximal or distal half of the infrarenal aorta was exposed to transluminal RFA, the untreated half served as an intra-individual control. Optical coherence tomography (OCT) was performed directly after RFA.
Results: Within 24 hours after RFA, no plaque ruptures or adverse events were observed by OCT or histology. Treated regions showed widespread decellularization of intimal, medial and (to a lesser extent) adventitial layers, which were recellularized after 7 and 28 days. Vasa vasorum density was not different between both regions at short-term (24 hours; RFA 19.8±5.1 vs. control 29.2±8.3/mm2; p=0.15) or long-term follow-up (7 days; 39.1±11.5 vs. 41.7±8.6/mm2; p=0.81 and 28 days; 46.4±13.4 vs. 38.5±6.6/mm2; p=0.06). After 7 days, treated regions were comparable to control areas with respect to plaque size (5.6±1.7 vs. 5.5±1.5mm2; p=0.62), intimal collagen (34.6±11.9 vs. 32.7±13.0%; p=0.22) and macrophage content (14.3±2.8 vs. 18.5±5.8%; p=0.32). RFA-treated regions did show a major decrease in intimal smooth muscle cell (αSMA) content (1.8±0.4 vs. 18.0±5.9%; p=0.038), which remained decreased after 28 days (6.8±3.8 vs. 12.6±1.6%; p=0.020). Again, after 28 days no differences were observed in plaque area (4.6±0.9 vs. 4.4±1.1 mm2; p=0.46), intimal collagen (39.2±9.1 vs. 40.3±12.4%; p=0.85) or macrophage content (13.2±2.5 vs. 12.6±2.0%; p=0.73).
Conclusion: Radiofrequency ablation of the rabbit atherosclerotic plaque is safe and leads to a major reduction in αSMA content, but does not affect other aspects of plaque stability over time. It may thus serve as a therapeutic option for major (re)stenosis in peripheral arterial disease.
Author Disclosures: G. Ellenbroek: None. G. van Hout: None. S. de Jager: None. L. Timmers: None. A. Vink: None. R. Goldschmeding: None. P. van der Kraak: None. G. Pasterkamp: None. I. Hoefer: None. P. Doevendans: None. Y. Appelman: None.
- © 2016 by American Heart Association, Inc.