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Dual anti-platelet therapy with aspirin and clopidogrel must be continued for a longer time period after implantation of

DES than after BMS implantation, and treatment for 12 months is usually recommended.

Aspirin should be continued life-long. Clinically, there is a temporal link between cessation of dual anti-platelet therapy

and the occurrence of stent thrombosis (9), and recently presented registry data indicate that some patients might

benefit from prolonged dual anti-platelet therapy (10,11).However, dual anti-platelet therapy for more than 12 months has not been tested in clinical trials and is, therefore,

currently not recommended, because long-term dual anti-platelet therapy is associated with an increased risk of

bleeding complications (12). The challenge is to find the optimal balance in order to achieve the lowest possible risk of

stent thrombosis without subjecting patients to an unnecessary risk of bleeding complications.

Perspectives: future prevention of stent thrombosis

Stents coated with new cytotoxic drugs and polymers may have different properties in terms of affecting

endothelialisation, vascular inflammation and induction of tissue factor activity.

Coating with NO-donors may decrease platelet adhesion and aggregation.

Stents coated with CD34-antibodies may capture circulating endothelial progenitor cells and may be able to prevent

thrombosis by increasing and accelerating endothelial coverage.

Furthermore, development of biodegradable stents might also be a way to decrease the incidence of late and very late

stent thrombosis.

Anti-thrombotic therapy is likely to be optimised with the development of new more efficient anticoagulants and anti-

platelet drugs with a lower risk of bleeding complications. Patients and health personnel should be informed about the

risk associated with premature cessation of therapy.

Development of new tests able to assess platelet inhibition may identify patients with a reduced benefit from aspirin or

clopidogrel and may make it possible to further individualise and optimize anti-platelet therapy.

The risk of stent thrombosis has been a known complication after PCI for quite a long time and might be increased afterimplantation of DES. The issue of in-stent thrombus formation, therefore, has attracted great attention once again.

Though evidence remains inconclusive, some studies indicate that the incidence of late and very late stent thrombosis

is increased after DES implantation.

Importantly, it is unknown whether very late stent thrombosis is a time limited phenomenon and, thus, the problem might

increase, if events continue to accrue over time.

As a consequence, large-scale clinical trials with long-term follow-up as well as mechanistic studies are highly

warranted. Currently, it is not known whether very late stent thrombosis is prevented with an extended course of dual

anti-platelet therapy.

Certainly, the issue of stent thrombosis emphasizes the importance of careful patient selection and individualised

therapy which, in future, might partly be based on measurement of the intensity of platelet inhibition.

References

1. Morice MC, Serruys PW, Sousa JE, Fajadet J, Ban HE, Perin M, Colombo A, Schuler G, Barragan P,

Guagliumi G, Molnar F, Falotico R. A randomized comparison of a sirolimus-eluting stent with a standard stent

for coronary revascularization. N Engl J Med 2002;346(23):1773-1780.

2. Moses JW, Leon MB, Popma JJ, Fitzgerald PJ, Holmes DR, O'Shaughnessy C, Caputo RP, Kereiakes DJ,

Williams DO, Teirstein PS, Jaeger JL, Kuntz RE. Sirolimus-eluting stents versus standard stents in patients

with stenosis in a native coronary artery. N Engl J Med 2003;349(14):1315-1323.

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3. Iakovou I, Schmidt T, Bonizzoni E, Ge L, Sangiorgi GM, Stankovic G, Airoldi F, Chieffo A, Montorfano M,

Carlino M, Michev I, Corvaja N, Briguori C, Gerckens U, Grube E, Colombo A. Incidence, predictors, and

outcome of thrombosis after successful implantation of drug-eluting stents. JAMA 2005;293(17):2126-2130.

4. Food and Drug Administration. Circulatory System Devices Panel Meeting. 2006.

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coronary thrombosis: biological mechanisms and clinical implications. Circulation 2007;115(8):1051-1058.

6. Gurbel PA, Bliden KP, Guyer K, Cho PW, Zaman KA, Kreutz RP, Bassi AK, Tantry US. Platelet reactivity in

patients and recurrent events post-stenting: results of the PREPARE POST-STENTING Study. J Am Coll

Cardiol 2005;46(10):1820-1826.

7. Gurbel PA, Bliden KP, Samara W, Yoho JA, Hayes K, Fissha MZ, Tantry US. Clopidogrel effect on platelet

reactivity in patients with stent thrombosis: results of the CREST Study. J Am Coll Cardiol 2005;46(10):1827-

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thrombosis is associated with an impaired response to antiplatelet therapy. J Am Coll Cardiol

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9. Pfisterer M, Brunner-La Rocca HP, Buser PT, Rickenbacher P, Hunziker P, Mueller C, Jeger R, Bader F,

Osswald S, Kaiser C. Late clinical events after clopidogrel discontinuation may limit the benefit of drug-eluting

stents: an observational study of drug-eluting versus bare-metal stents. J Am Coll Cardiol 2006;48(12):2584-

2591.

10. Eisenstein EL, Anstrom KJ, Kong DF, Shaw LK, Tuttle RH, Mark DB, Kramer JM, Harrington RA, Matchar DB,

Kandzari DE, Peterson ED, Schulman KA, Califf RM. Clopidogrel use and long-term clinical outcomes after

drug-eluting stent implantation. JAMA 2007;297(2):159-168.

11. Michael Maeng, Lisette O.Jensen, Anne Kaltoft, Per Thayssen, Hans H.Hansen, Morten Bttcher, Jens

F.Lassen, Lars R.Krusell, Lars Pedersen, Klaus Rasmussen, Knud N.Hansen, Sren P.Johnsen, Henrik

T.Srensen, Leif Thuesen. Stent thrombosis after implantation of drug-eluting or bare metal coronary stents in

Western Denmark. Presented at the ACC Congress, March. 2007.

12. Bhatt DL, Fox KA, Hacke W, Berger PB, Black HR, Boden WE, Cacoub P, Cohen EA, Creager MA, Easton

JD, Flather MD, Haffner SM, Hamm CW, Hankey GJ, Johnston SC, Mak KH, Mas JL, Montalescot G, Pearson

TA, Steg PG, Steinhubl SR, Weber MA, Brennan DM, Fabry-Ribaudo L, Booth J, Topol EJ. Clopidogrel and

aspirin versus aspirin alone for the prevention of atherothrombotic events. N Engl J Med 2006;354(16):1706-

1717.

Autor: Grove E.C.L. MD and Kristensen S.D. MD, DMSc, FESC

Fuente: European Society of Cardiology

Ultima actualizacion: 06 DE FEBRERO DE 2009