New Stent Showed Good Long-Term Safety


NEW ORLEANS – Presuming that the Resolute zotarolimus-eluting coronary stent enters the U.S. market within the next year, interventionalists likely will rely on data from two key studies to weigh how it matches up against its main competition, the Xience V/Promus everolimus-eluting coronary stent.

Two features seemed to especially capture the attention of the cardiologists who reported the data at the meeting and those who heard it: the impressive performance of the zotarolimus-eluting stent (ZES) in patients with diabetes, and the long-term safety of the ZES compared with the everolimus-eluting stent (EES) for stent thrombosis.

One of the two studies was the RESOLUTE All Comers trial, which compared the ZES against the EES in a randomized trial of 2,292 European patients for whom follow-up now extends to 2 years.

The second study, RESOLUTE US, evaluated the new ZES in a series of 1,402 U.S. patients with a high, 34% prevalence of diabetes; this study had a special focus on the stent's performance in the 150 narrow, 2.25-mm-diameter arteries included in the series.

The roughly 2,500 ZES recipients included in these two studies form about half of the 5,227 total–patient worldwide experience with the stent to date, and constituted what Medronic, the company developing the Resolute ZES, submitted to the Food and Drug Administration for marketing approval and labeling.

One major take on these data by experts was that the ZES showed good overall performance that matched well with the performance of the EES.

The two stents “seemed to be fairly equivalent for most of the important safety and efficacy metrics. They are both superb,” said Dr. Martin B. Leon, director of the center for interventional vascular therapy at Columbia University in New York, and lead investigator for the RESOLUTE US study.

But other interventionalists hearing the data from both studies weren't as completely convinced.

“My initial take on the data is that [the ZES] doesn't seem to be better than the Xience stent, which is a very good stent and the dominant stent we use [in the United States] at this time,” Dr. Abhiram Prasad, an interventional cardiologist and professor of medicine at the Mayo Clinic in Rochester, Minn., said in an interview.

Safety concerns with the ZES date back to the initial, 12-month follow-up report, the first indication that the ZES fell short compared with the EES on the rate of stent thrombosis in the RESOLUTE All Comers trial. The New England Journal of Medicine report last year (2010;363:136-46) documented 18 patients (1.6%) with definite or probable stent thrombosis in the ZES arm, compared with 8 cases (0.7%) of definite or probable stent thrombosis in the EES group, a significant difference.

The new, 24-month follow-up data provided some reassurance on safety, in that the stent thrombosis gap between the two stents stayed stable. During an extra year of follow-up, three new cases of definite or probable stent thrombosis occurred in each of the two treatment arms, said Dr. Patrick W. Serruys, professor of interventional cardiology at Erasmus University and the Thoraxcentrum, Rotterdam, and lead investigator for the RESOLUTE All Comers trial. Aside from this one early safety deviation, the ZES and EES continued to show virtually identical efficacy performance through the 2 years of study, he showed in the updated data. Concurrently with his report at the meeting, the results appeared in an article published in the Lancet (2011 [doi:10. 1016/S0140 6736(11)60404-2]).

Dr. Serruys, as well as others, chalked up the early difference in stent thrombosis rates to chance, and to some isolated poor performance in certain sites undertaking the coronary interventions.

“Numerically, the stent thrombosis is very small, a difference of 21 vs. 11 patients in more than 2,000 total patients. It could be the play of chance,” Dr. Serruys said.

The RESOLUTE US results seemed to add to the safety assurance. In those 1,402 patients, two cases (0.1%) of stent thrombosis occurred during 12 months of tracking. Concurrently with Dr. Leon's report, the RESOLUTE US results appeared in the Journal of the American College of Cardiology (2011 April 4 [doi:10.1016/j.jacc.2011.03.005]).

“This is one of the lowest 1-year stent thrombosis rates ever reported,” noted Dr. Leon. “I take from this that it's a safe stent.”

The pattern of some of the earliest cases of stent thrombosis in RESOLUTE All Comers suggested that it may have been caused more by operator failings and less by problems with the stent itself. During the study's first 30 days, stent thrombosis occurred in nine ZES patients and one EES patient, making up most of the differential that wound up haunting the ZES arm through the next 2 years. “Stent thrombosis during the first 30 days is procedure related,” and generally the stent itself plays no role, said Dr. Alan C. Yeung, professor of medicine and director of cardiac catheterization at Stanford (Calif.) University.


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