Dr. Dean Kereiakes knows a thing or 2 about coronary stents – he’s been a principal investigator in a number of clinical trials evaluating coronary stents over the past 20 years. So it counts when Kereiakes names the Synergy stent made by Boston Scientific‘s (NYSE:BSX) “the safest stent yet.”
An interventional cardiologist at the Christ Hospital, he was also a principal investigator in Boston Scientific’s 1,684-patient Evolve II trial, comparing the Synergy bioresorbable-polymer stent with the Promus Element Plus device. The study’s primary endpoint was target lesion failure at 12 months.
Previous work demonstrated that drug-eluting stents reduce cardiac events compared with bare-metal stents, but researchers also observed that permanent polymers like the one used with the Promus Element can cause chronic inflammation and increase the risk of later cardiac events.
Although both stents release everolimus in comparable dose densities, they differ dramatically in strut size and polymer distribution. Kereiakes told Drug Delivery Business News that Synergy’s thin struts allow physicians to more delicately snake the device through a patient’s artery. That’s because the Synergy stent features thinner struts than the Promus Element Plus stent at 75 μm compared to 81 μm, he told us.
“It slithers, so to speak, and it makes our job easier. I think that probably the major appeal to interventionists is that they can feel the difference,” he said. “When you put the stent up, instead of leaving nature alone and keeping the bends that God gives us, if you will, in our arteries, the typical less-conformable stent will tend to straighten out those bends.”
The stents also differ in drug-releasing polymer distribution, Kereiakes explained. The Promus Element Plus has conformal distribution, meaning the polymer completely surrounds the strut. The Synergy stent only has polymer on the outside or abluminal surface of the strut; Kereiakes said previous work shows that endothelial coverage and function is better with abluminal polymer distribution compared to conformal.
The small amount of PLGA polymer on the Synergy stent delivers drugs as it absorbs over 3 to 4 months. Other polymers used in competing devices take 9 to 18 months to resorb, he said.
“Thinner struts, flexibility, conformability, the deliverability, the fracture resistance – it’s all there,” Kereiakes said.
Data from Evolve II show that the Synergy stent was non-inferior to the Promus stent for target lesion failure at 1 year. At 2 years, target lesion failure was 9.4% and 8.5% for Synergy and Promus, respectively. Adverse events including death and revascularization were not significantly different between the 2 treatment groups, according to the study.
The researchers observed no additional stent thrombosis events with the Synergy stent beyond day 6 through the 2-year follow-up mark.
Researchers concluded that the Synergy stent, which proved to be as effective as the Promus device, exhibited a low stent thrombosis rate at 1 year, 2 year and 3 years post-implantation.
“Beyond 1 to 2 years, we had about an 85% relative reduction in stent thrombosis favoring Synergy compared to Promus Element Plus,” Kereiakes said.
At 1 year, the stent thrombosis rate was numerically less, but not statistically significantly less, he added.
Kereiakes has worked with the Synergy stent before, supporting its FDA approval in 2015 and evaluating it in a cohort of diabetic patients. Kereiakes intends to publish a 5-year follow-up of the Evolve II participants.
He told us that his job as a cardiologist and as a principal investigator is to bring safer, more efficacious devices to patients and to his colleagues.
“I’m interested in making every case easier,” he said. “I don’t want to be jamming a relatively rigid device down an artery, or having to use aggressive guide catheter techniques to get better support. If I have a device that makes my job easier and it is much better for the patient, there is no question – the complication rate is better, the case usually is quicker, easier, and we get a good result.”