Extending Clopidogrel Past 1 Year Improves Outcomes in DES, But Not BMS Patients

CHICAGO, IL—While prolonging clopidogrel treatment beyond 1 year in patients with acute coronary syndromes (ACS) may reduce the risk of death or myocardial infarction (MI) in those who receive a drug-eluting stent (DES), the same was not seen after bare metal stent (BMS) implantation, according to results of a study presented on November 17, 2014, at the American Heart Association Scientific Sessions. 

Neil J. Wimmer, MD, MSc, of Brigham and Women's Hospital (Boston, MA), and colleagues looked at 18,289 ACS patients who underwent PCI in the VA health system from 2002 to 2006 and were event free at 12 months. Of the 9,336 treated with DES and 8,943 with BMS, 43.2% and 64.9%, respectively, were on clopidogrel for 12 months or less. Average patient age was 63 years and almost all (98%) were men. Slightly more than two-thirds had had a prior MI and about 7% had creatinine levels of at least 2.0 mg/dL.

Among DES patients, the risk of both death and death or MI decreased if clopidogrel was continued past 1 year, but no benefit was seen in the BMS cohort (table 1). 

The results were confirmed by multivariable and propensity score analyses. 

Comparisons With the DAPT Study

Limitations of the study, according to Dr. Wimmer, are the retrospective analysis, the fact that the study only included first-generation stents, and no endpoint adjudication. Even though first-generation stents are no longer in use, “there are obviously many patients walking around who still have these stents in and so we want to know how to treat them in the clinical realm,” he stressed. 

Even so, the findings have implications similar to those of the DAPT Study, also presented at the meeting, Dr. Wimmer commented. “The decision to prolong clopidogrel likely should be tailored to patient and procedural characteristics,” he said.

With regard to the disparity between DES and BMS, Dr. Wimmer said it was “a bit surprising” as patients given a year of treatment “all are sort of in the secondary prevention realm and would [be expected to] do well, particularly given that many of the events are not related to the stent itself.” 

But “it’s hard to know the exact mechanism for our finding,” he continued. “If you look at the trial data presented yesterday [in DAPT], about 50% of the MIs that were adjudicated were not related to stent thrombosis. [That’s] a large randomized trial, so it’s hard to know why this happens here.”

Addressing the timing of the analysis, Dr. Wimmer said the results would be different if the study was conducted now. “We started treating patients very differently in terms of who got BMS and who got DES after 2006 and so it makes the interpretation of more recent nonrandomized data that much more difficult,” he concluded. “It's harder to adjust for it statistically.”

Source:
Wimmer NJ. The impact of prolonged clopidogrel beyond 12 months after coronary stenting in patients with acute coronary syndromes. Presented at: American Heart Association Scientific Sessions; November 17, 2014; Chicago, IL.

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