SCAAR: New-generation DES reduced stent thrombosis risk

New-generation drug-eluting stents were associated with a significant reduction in the risk for early or late stent thrombosis compared with bare-metal stents in patients with STEMI, according to findings from the Swedish Coronary Angiography and Angioplasty Registry.

The researchers highlighted ongoing long-term safety issues in patients with acute STEMI who receive DES and evaluated stent thrombosis over the course of a 3-year follow-up in a cohort of 34,147 patients with STEMI from the Swedish Coronary Angiography and Angioplasty Registry (SCAAR). There were 4,811 patients treated with new-generation DES, 4,271 patients treated with old-generation DES and 25,065 patients treated with BMS. Patients underwent PCI between January 2007 and January 2013.

The researchers calculated estimates for early or late stent thrombosis (up to 1 year) and very late definite stent thrombosis (after 1 year).

Early or late stent thrombosis risk was significantly lower in the new-generation DES arm (HR=0.65; 95% CI, 0.43-0.99) and the old-generation DES arm (HR=0.60; 95% CI, 0.41-0.89) compared with the BMS arm. The researchers added that there was no significant difference between the new- and old-generation DES arms in terms of stent thrombosis.

New-generation DES and BMS were associated with a similar rate of very late stent thrombosis risk (HR=1.52; 95% CI, 0.78-2.98). However, compared with BMS, the old-generation DES yielded a higher rate of very late stent thrombosis (HR=2.88; 95% CI, 1.70-4.89).

“The current STEMI guidelines might require an update in light of the results of this and other recent studies,” the researchers concluded.

In an accompanying editorial, Bradley H. Strauss, MD, PhD, and Mony Shuvy, MD, both of the Schulich Heart Center and Sunnybrook Health Sciences Center at the University of Toronto in Canada, suggested that the current study advances the field of stent thrombosis associated with DES in STEMI. They highlighted data demonstrating stent thrombosis rates of 0.9% for second-generation DES, 1.1% for first-generation DES and 1.5% for BMS in the first year of follow-up.

“Between the first and the third years, the absolute rate of [stent thrombosis] was 2-fold higher in the first-generation DES group compared with the BMS group,” they wrote. “A second, potentially more clinically important observation from the study was a significantly lower mortality rate in patients treated with DES (either first or second generation) compared with patients treated with BMS; these differences were evident early after the stent procedure.”

Shuvy and Strauss suggested that because stent thrombosis is rare, many randomized clinical trials for this event lack statistical power. Therefore, large registries like the current analysis are necessary to move the body of information forward. The editorialists added that the current results are consistent with other meta-analyses investigating similar patient populations.

The study does, however, have limitations, according to Strauss and Shuvy. “The study lacks important clinical data, such as the duration of dual-antiplatelet therapy in the various groups,” they wrote. “Differences in antiplatelet agents and procedural anticoagulation between study groups also may have contributed to the outcomes.”

Specifically, ticagrelor (Brilinta, AstraZeneca) was used more frequently in the first-generation DES group and clopidogrel was used more frequently in the BMS group. DES patients were more likely to receive bivalirudin (Angiomax, The Medicines Company) and BMS patients predominantly received glycoprotein IIb/IIIa inhibitors.

In conclusion, Shuvy and Strauss wrote, “The SCAAR results are reassuring and should mitigate concerns about late and very late [stent thrombosis] with second-generation DES in STEMI patients.” The authors added that more recent data suggest that further investigation of DAPT for DES in STEMI is necessary. “As our daily practices evolve with this new knowledge, we expect that future STEMI guidelines for DES also will need to be updated,” they wrote.

For more information:

Sarno G. J Am Coll Cardiol. 2014;64:16-24.

Strauss BH. J Am Coll Cardiol. 2014;64:25-27.

Disclosure: The researchers report financial disclosures with AstraZeneca, Biosensors, Biotronik, Boston Scientific, Eli Lilly, Iroko, Medtronic, Sanofi Aventis, Terumo, The Medicines Company and Volcano. Shuvy and Strauss report no relevant financial disclosures.