Original title: Stent thrombosis in new-generation drug-eluting stents in patients with STEMI undergoing primary PCI: a report from SCAAR. Reference: Sarno G et al. J Am Coll Cardiol. 2014;Epub ahead of print.

This study evaluated 34147 consecutive patients suffering acute myocardial infarction with ST-segment elevation included in the SCAAR registry (Swedish Coronary Angiography and Angioplasty Registry) undergoing primary angioplasty with last generation drug-eluting stents (n = 4811), first generation (n = 4271) or with conventional stent (n = 25065) between January 2007 and January 2013. The new generation of drug-eluting stents included the Endeavor Resolute (Medtronic, Minneapolis, MN), Xience V and Xience Prime (Abbott Vascular, Santa Clara, CA), Promus and Promus Element (Boston Scientific, Natick, MA). The first generation included the Cypher and Cypher Select (Cordis, Miami, FL), Taxus Express and Taxus Liberté (Boston Scientific) and Endeavor (Medtronic). 

An analysis adjusting for propensity score showed a lower risk of early and late thrombosis with 2nd generation drug-eluting stents versus conventional stents (HR 0.65, CI 95% 0.43 to 0.99; p=0.04) as well as with 1st generation pharmacological stents versus conventional stents (HR 0.6, CI 95% 0.41 to 0.89, P = 0.01). No significant differences were observed for early or late thrombosis between the two generation drug-eluting stents (HR 0.73, CI 0.44 to 1.21, P = 0.22). 

However, when considering very late thrombosis of drug-eluting stents 1st generation showed higher risk than conventional stents (HR 2.88, 95% CI 1.70 to 4.89, P <0.01). However, when considering the very late thrombosis of 1st generation drug-eluting stents, showed higher risk than conventional stents (HR 2.88, CI 95% 1.70 to 4.89, P <0.01). Within 3 years of primary angioplasty, all-cause mortality was lower for both generations of drug-eluting stents compared with conventional stents. 

Conclusion 

Patients who received primary angioplasty with new generation drug-eluting stents had lower risk of early and late thrombosis compared with conventional stents. The risk of very late thrombosis was low and comparable between bare metal stents and new generation drug-eluting stents while 1st generation drug-eluting stents showed an increased risk of very late thrombosis. Current guidelines for acute coronary syndromes with ST-segment elevation require updating in the light of these results and other recent studies. 

Editorial comment 

There is no time recording registry of dual anti-aggregation that each group received, although this is unlikely to affect the rate of very late thrombosis. Early discontinuation of dual anti-aggregation and other factors such as sub-expansion malapposed or lesion complexity are more related factors to early or late thrombosis and much less to very late thrombosis. 

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