Biodegradable-polymer drug-eluting stents (DES) may take a backseat to one type of second-generation durable-polymer stent, based on a network meta-analysis published in the Feb. 4 issue of the Journal of the American College of Cardiology.

Biodegradable-polymer stents were designed to overcome an increased risk of late stent thrombosis that was associated with first-generation durable-polymer DES, which in turn offered a lower risk of restenosis and target vessel revascularization compared with bare-metal stents (BMS).

Newer generation DES incorporated more biocompatible durable polymers, with the goal of reducing reactions that may have led to late stent thrombosis. The use of biodegradable polymers took a different route: providing a polymer that was bioresorbed, dampening the inflammation trigger after DES implantation.

Tullio Palmerini, MD, of Policlinico Sant’ Orsola in Bologna, Italy, and colleagues performed the meta-analysis to assess the relative safety and efficacy of biodegradable-polymer DES and second-generation DES.

“Studies comparing these new devices have in general been insufficiently powered to determine significant differences in individual components of safety (death, cardiac death, myocardial infarction [MI], and ST [stent thrombosis]) and efficacy (TVR [target vessel revascularization]),” they explained. “Network meta-analyses and mixed treated comparisons are novel research methods capable of comparing different treatments with a common reference treatment, and their role in clinical research has been established.” 

For the meta-analysis they included studies that used two CE Mark biodegradable-polymer biolimus-eluting stents: Biomatrix (Biosensors International) and Nobori (Terumo Corp.). For DES comparators they chose FDA-approved stents. They looked through MEDLINE, Cochrane Collaboration databases, EMBASE, TCTMD, ClinicalTrials.gov, meeting presentations and other sources for randomized clinical trials.

The meta-analysis included 89 trials with almost 85,500 randomized patients. At one-year follow-up, they found biodegradable-polymer biolimus-eluting stents had lower rates of TVR compared with fast-release zotarolimus-eluting stents and similar rates of cardiac death/MI, MI and TVR compared with other second-generation durable-polymer DES. The biodegradable-polymer DES also showed improved outcomes compared with paclitaxel-eluting stents.

The biodegradable-polymer DES also had higher one-year rates of definite ST and higher rates of long-term definite ST compared with durable-polymer-based cobalt-chromium everolimus-eluting stents, though.

“[L]arge-scale studies will be required to determine whether the potential late benefits of a BP [biodegradable polymer] can more than offset the early benefits of a thromboresistant DP [durable polymer],” Palmerini and colleagues  wrote. “In this regard, the extent to which the DP provides clinically important thromboresistant properties in the very late period is undetermined.”

John A. Bittl, MD, of Ocala Heart Institute in Ocala, Fla., took a stronger stand in an accompanying editorial. The study strengths and robust results “demonstrate that BPs do not outperform fluoropolymer DPs,” he wrote. “The analysis in the current report suggests that the DP-CoCr-EES [durable-polymer cobalt-chromium everolimus-eluting stents] and their PtCr [platinum chromium] analogs are the preferred devices for coronary stenting in current practice.”