SCAAR: Lower Risk of Early, Late Stent Thrombosis with Newer DES vs BMS in STEMI

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Treatment with newer-generation drug-eluting stents (DES) results in a lower risk of early and late stent thrombosis and similar risk of very late stent thrombosis compared with bare-metal stents (BMS) in patients with ST-segment elevation myocardial infarction (STEMI), according to a Swedish registry report published online June 30, 2014, ahead of print in the Journal of the American College of Cardiology.

A propensity-adjusted Cox regression landmark analysis showed less risk for early/late stent thrombosis in both DES groups vs BMS. However, there were no differences between DES cohorts (table 1). 

Table 1. Adjusted Risk of Early/Late Stent Thrombosis

Abbreviations: n-DES = new DES, o-DES = old DES.

For very late stent thrombosis, the only difference observed was a higher risk in the older-generation DES group vs BMS (HR 2.88; 95% CI 1.70-4.89; P < .01).

Within 3 years after PCI, there were 3,579 deaths. Mortality risk was lower in both the newer (adjusted HR 0.55; 95% CI 0.48-0.62) and older (adjusted HR 0.58; 95% CI 0.52-0.65) DES groups vs BMS. There was no difference in mortality between the DES arms.

Inherent Advantages with Newer Stents  

“Our finding of a higher risk of very late [stent thrombosis] in the [old DES] group compared with the BMS group confirms concerns about the use of [old DES] in the STEMI setting, which have led to a Class IIA recommendation for the use of DES in the current STEMI guidelines,” Dr. Sarno and colleagues write.

In an email with TCTMD, Deepak L. Bhatt, MD, MPH, of Brigham and Women’s Hospital (Boston, MA), said, “This well-done analysis from the large SCAAR registry reinforces what randomized clinical trials, simple meta-analyses, and network meta-analyses have found rather consistently…. This particular analysis examined patients with STEMI undergoing primary PCI, so it is particularly reassuring that second-generation DES performed so well and appeared very safe.”

In an editorial accompanying the study, Bradley H. Strauss, MD, PhD, and Mony Shuvy, MD, both of the University of Toronto (Toronto, Canada), explain that “second-generation DES have theoretical advantages over first-generation DES because of the thin-strut design, reduced polymer layer, and, potentially, the use of a novel drug.”

They say the results are “reassuring and should mitigate concerns” about stent thrombosis with second-generation DES in STEMI. The SCAAR data are also consistent with several larger meta-analyses of DES vs BMS in this patient group, they write.

More on Antiplatelet Agents

Lacking data on dual antiplatelet therapy, however, makes it hard to identify the cause of heightened stent thrombosis risk in these patients, according to the study authors. “However, it is unlikely that the DAPT duration has affected the results of very late [stent thrombosis],” they write. “The early cessation of DAPT and other procedural factors, such as stent underexpansion, malapposition, and lesion complexity, are known to contribute mainly to the development of early and late [stent thrombosis].”

The editorial picks up on the missing antiplatelet therapy data as well, noting that differences in these agents “and procedural anticoagulation between study groups also may have contributed to outcomes."

Additionally, Drs. Strauss and Shuvy say that the mortality differences between BMS and first- and second-generation DES are “intriguing, but should raise concerns about unmeasured selection bias in the study despite the propensity analysis.”

Ultimately, “[t]he current guidelines on STEMI might require an update in light of the results of this and other recent studies,” the authors conclude.

Dr. Bhatt added that “while we should wait to see what the guidelines say, likely many patients with STEMI can be treated with second-generation DES (and probably ought to be)."

 Sources: 
1. Sarno G, Lagerqvist B, Nilsson J, et al. Stent thrombosis in new-generation drug-eluting stents in patients with STEMI undergoing primary PCI: a report from SCAAR. J Am Coll Cardiol. 2014;Epub ahead of print.

2. Strauss BH, Shuvy M. Stent thrombosis following drug-eluting stents in STEMI: “much ado about nothing?” [editorial]. J Am Coll Cardiol. 2014;Epub ahead of print.

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