EVOLVE Data Presented for Boston Scientific's Synergy Bioabsorbable DES

November 11, 2011—Boston Scientific Corporation (Natick, MA) announced that results from the EVOLVE first-human-use trial demonstrated the noninferiority of the company’s Synergy everolimus-eluting stent system compared to its Promus Element everolimus-eluting stent system in treating de novo coronary artery lesions. The trial provided 30-day clinical and 6-month angiographic primary endpoint data evaluating the safety and effectiveness of the bioabsorbable polymer-coated Synergy stent. Principal Investigator Prof. Ian T. Meredith, MBBS, PhD, presented the results during a late-breaking clinical trial session at the annual Transcatheter Cardiovascular Therapeutics scientific symposium in San Francisco.

According to Boston Scientific, the prospective, randomized, single-blind, noninferiority trial enrolled 291 patients at 29 sites in Europe, Australia, and New Zealand. Patients were randomized to one of two dose formulations of everolimus used on the Synergy stent, which employs an ultra-thin abluminal bioabsorbable polymer, or to the commercially available (outside of the United States) Promus Element stent, which employs the everolimus drug and a permanent durable polymer. One formulation of the Synergy stent used an everolimus dose and release profile similar to the Promus Element stent, and the second formulation of the Synergy stent used a similar release profile but half the dose of everolimus.

“The Synergy stent met the primary noninferiority endpoint of 6-month late loss compared to the Promus Element stent, demonstrating effectiveness of drug elution from this abluminal bioabsorbable polymer,” commented Prof. Meredith. “The platform also appears to be safe with very low rates of myocardial infarction and revascularization and no reported cardiac deaths or stent thrombosis. The Synergy stent is designed to address potential limitations with durable polymer coatings used on currently available drug-eluting stents, which may be associated with chronic inflammation and impaired healing. The impressive clinical and angiographic results from EVOLVE bode well for this innovative new coronary stent technology.”

The primary angiographic endpoint of independently adjudicated mean late loss at 6 months was 0.10 mm for the Synergy stent and 0.13 mm for the half-dose Synergy stent compared with 0.15 mm for the Promus Element stent (P < .001 for the noninferiority comparison for both Synergy doses versus Promus Element). Additional 6-month angiographic outcomes for diameter stenosis and binary restenosis showed no statistical differences between the Synergy and Promus Element stents, the company noted.

Boston Scientific stated that the trial met the primary clinical endpoint of target lesion failure (TLF) at 30 days, which was defined as target vessel–related cardiac death, target vessel–related myocardial infarction (MI), or ischemia-driven target lesion revascularization (TLR). At 30 days, TLF in both Synergy stent arms was not statistically different from the Promus Element stent. The TLF rate was 1.1% for the Synergy stent versus 0% for the Promus Element stent (P = .49 for superiority comparison) and 3.1% for the half-dose Synergy stent (P = .12 for superiority comparison with the Promus Element stent). 

TLF continued to show no significant differences among the three stent groups out to 6 months with rates of 2.2% for the Synergy stent versus 3.1% for the Promus Element stent (P = 1.00) and 4.1% for the half-dose Synergy stent (P = .72 versus the Promus Element stent). Clinical follow-up at 6 months demonstrated no events of cardiac death, Q-wave MI, or stent thrombosis. The MI rate was 1.1% for the Synergy stent, 0% for the Promus Element stent (P = .49), and 3.1% for the half-dose Synergy stent (P = .25), all presenting as non-Q-wave MI. The TLR rate was 1.1% for the Synergy stent, 3.1% for the Promus Element stent (P = .62), and 1% for the half-dose Synergy stent (P = .62).

The company noted that the Synergy stent uses a bioabsorbable polylactic-co-glycolic acid polymer and everolimus drug combination to create an ultra-thin, uniform coating applied to the abluminal surface of the stent. After the drug has been delivered, the bioabsorbable coating is designed to resorb within 4 months, leaving only a bare-metal stent. This technology is designed to provide the same degree of restenosis reduction as a conventional drug-eluting stent while offering faster and more complete vessel healing after stent implantation, which could potentially reduce the duration of postprocedure dual-antiplatelet therapy. The Synergy stent features the same platinum chromium alloy and similar stent design used in the Promus Element stent, enabling thinner struts and increased conformability, deliverability, and flexibility while reducing recoil and improving visibility.

In the United States, the Synergy stent and the Promus Element stent are investigational devices that are limited by applicable law to investigational use only and are not available for sale. Boston Scientific Corporation received CE Mark approval for the Promus Element stent in October 2009.