A Cagey Proposition

Restenosis after percutaneous coronary intervention (PCI)occurs as a complex immune and proliferative response to injury. Even in the drug-eluting stent (DES) era, restenotic risk is not insubstantial, with reported rates of angiographic restenosis up to 18.9% and target vessel revascularization up to 12.1% in complex lesions or patients with diabetes mellitus.¹ Among preventative strategies, focus on optimization of stent expansion with adequate lesion preparation and minimization of vessel injury with avoidance of balloon slippage (“watermelon seeding”) has led to development of the Cutting^® and FX miniRail^® ballooncatheters as well as other atheroablative devices. Unfortunately, no clear “new-age” solution has been declared, with several trials showing equivalence with plain-old balloon angioplasty in terms of clinical outcomes either with or without adjunctive stenting.
After development of in-stent restenosis, definitive treatment has been elusive, with similarly underwhelming results from conventional percutaneous transluminal coronary angioplasty (PTCA), cutting balloon angioplasty, high-speed rotational atherectomy and brachytherapy. In the RIBS-II trial, DES use in patients with in-stent restenosis reduced angiographic restenosis (11% vs. 39%) and need for target vessel revascularization (11% vs. 30%) compared to PTCA.² However, this strategy is limited in smaller vessels (< 2.5 mm), after multiple stents, and in patients unable to take long-term dual antiplatelet regimen. Consequently, restenosis remains a major clinical challenge, requiring innovation in both prevention and therapy.
In this issue of the Journal, Fonseca et al³ present the promising first-in-man experience with Angiosculpt^®, a novel scoring balloon catheter, investigated as both a predilatation balloon for stenting of de novo coronary lesions and as “standalone” therapy for in-stent bare-metal restenosis. The Angiosculpt catheter comprises a semicompliant balloon wrapped by a nitinol cage of three spiral wires. When the balloon is inflated, the spiral wires provide a linear cutting surface that scores vessel wall plaque. Conceptually, this scoring function may allow lower-pressure dilatation and prevent watermelon seeding, thereby limiting overall vessel wall injury and aiding stent expansion.
In this study, 47 patients underwent successful Angiosculpt balloon predilatation prior to bare-metal stent implantation. Intravascular ultrasound (IVUS) examination directly after stent implantation in a 19-patient subset showed final minimal stent area of 6.6 ± 1.0 mm². There were no major procedural complications or 30-day major adverse cardiac events (MACE) including death, myocardial infarction or target lesion revascularization. Ischemia-driven need for repeat revascularization occurred in 10.2% cases by 6 months. In general, the use of Angiosculpt in de novo lesions appears safe and feasible, achieving adequate vessel predilatation for stent deployment.
The second arm of this study examined Angiosculpt balloon angioplasty as “standalone” therapy for bare-metal in-stent restenosis in 17 patients. Again, there were no major procedural complications or in-hospital adverse cardiac events. However, at 6-month follow up, ischemia-driven need for repeat revascularization occurred in 23.5% cases, and IVUS demonstrated a significant decrease in minimal luminal area at 6 months compared to immediately post intervention. Additional volumetric IVUS analysis showed a nonsignificant change in percent neointimal hyperplasia (NIH) volume between the original result and 6- month follow up, but a trend toward an increase in NIH volume and percent volume. It appears unlikely that Angiosculpt angioplasty will replace the use of DES for in-stent restenosis given these preliminary data, though further prospective study is necessary before definitive conclusions can be drawn. Nevertheless, especially in the subset of patients where DES use is problematic, Angiosculpt may provide a viable treatment option.
The positive tagline on this first-in-man safety and feasibility study would state that Angiosculpt coronary angioplasty demonstrated good acute- and mid-term procedural results with no major complications. The IVUS findings are on par with the expected results for acute- and mid-term procedural outcomes. It thus enters the armament of mechanical solutions to coronary artery stenosis.
However, criticisms remain. Whether it offers any advantage in restenosis rates or MACE over conventional balloon predilatation before stenting remains unknown, given the lack of a control arm and the small size of this pilot study. The theoretical advantage of the nitinol cage plaque-scoring system in facilitating vessel expansion with less vessel injury is unproven, and the role of Angiosculpt in the prevention and treatment of restenosis will require validation in larger randomized, controlled studies.
The history of plaque-modifying devices for de novo coronary stenosis and in-stent bare-metal restenosis is filled with promising technologies which, when examined more thoroughly in larger studies, has left a trail of disappointment. It remains to be seen whether this novel plaque modification scheme (anyone recall “forced-focus angioplasty”?) will render any better clinical results for our patients. It’s a cagey proposition indeed.