Newer-Generation DES Match Bare-Metal Stent Safety Beyond One Year: SCAAR

Shelley Wood

August 30, 2014

BARCELONA, SPAIN — Dubbed the "SCAAR scare," data from the Swedish Coronary Angiography and Angioplasty Register, presented in Barcelona at the World Congress of Cardiology 2006 that first raised alarm bells about an increased risk of stent thrombosis with drug-eluting stents (DES). Now—fittingly—new SCAAR data, also unveiled at an ESC congress, may once and for all reassure physicians that the newer-generation DES do not appear to carry the same, enduring risks as their forebears.

Dr Christoph Varenhorst (Uppsala Clinical Research Center, Sweden) presented seven years of data from 177 448 stents in patients enrolled in SCAAR here on the opening day of the European Society of Cardiology 2104 Congress .

The study looked specifically at rates of definite stent thrombosis in bare-metal, new-generation DES (n-DES), and older-generation DES (o-DES) beyond one year and out to at least five years, in all patients undergoing stenting procedures. o-DES included the Cypher (Cordis), Taxus Liberté (Boston Scientific) and Endeavor (Medtronic), while n-DES included Endeavor Resolute, Resolute Integrity (Medtronic), Xience V, Xience Prime/Xpedition (Abbott Laboratories), Promus, Promus Element/Plus (Boston Scientific), Nobori (Terumo), Biomatrix (Biosensors), and Orsiro (Biotronik). Earlier analyses from SCAAR have not focused solely on stent thrombosis, have not considered events before and after one year, or have looked at different subgroups of patients. Almost all, however—with the exception of the first, alarming report—have consistently showed improved safety with the newer devices.

Dr Christoph Varenhorst

In the latest comparison of all DES vs bare-metal stents, presented today, DES were associated with significantly lower rates of stent thrombosis out to 12 months, but higher rates beyond 12 months, echoing the earlier findings that first sparked the "ESC firestorm" of 2006.

When n-DES and o-DES were analyzed separately, however, the picture was strikingly different.

Between one and five years, the adjusted relative risk (RR) of stent thrombosis among o-DES was 1.81 (95% CI 1.44–2.28; p<0.001) compared with bare-metal stents. By contrast, the adjusted RR for n-DES was not significantly different from that of bare-metal stents (RR 1.17, 95% CI 0.88–1.56).

Varenhorst et al also looked at stent-thrombosis rates according to the type of drug used on the stent. In this analysis, both sirolimus- and paclitaxel-coated stents (the drugs used on the first-generation DES) emerged as the only drug types associated with a significantly increased risk of stent thrombosis over the long term.

Speaking with heartwire , Varenhorst stressed that the analysis did not compare stent-thrombosis rates between the different types of newer DES, it just compared rates of newer and older DES vs bare-metal stents. It's not possible from these data, he stressed, to identify whether the stent platform, the stent polymer, or the drug itself is responsible for the enhanced safety with the newer devices.

"The most important new finding is that the new-generation drug-eluting stents, after one year, have very low rates of stent thrombosis—as low as rates with bare-metal stents," he said in an interview. "This is in contrast to the old-generation DES that seem to continue to be associated with higher very late stent-thrombosis rates, and these seem to be maintained over five years in our study."

As such, the new SCAAR data also confirm the enduring risk of stent thrombosis associated with the first-generation drug-eluting stents. Varenhorst speculated to heartwire that this reflects the fact that first-generation DES actually play a causal role in promoting stent thrombosis and not, as some have suggested, that the newer DES actually promote healing. This is a "thrilling hypothesis," Varenhorst told his audience today, but "this is hypothetical at this time."

Of note, patients in Sweden do not receive dual antiplatelet therapy beyond one year, so the analysis looking at events beyond 12 months truly speak to the enhanced safety of the newer devices, he added.

Varenhorst disclosed institutional grants from AstraZeneca and honoraria/consultant/lecture fees from AstraZeneca and the Medicines Company.


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