[Post-implant antithrombotic treatment after intracoronary stents. Thrombotic occlusion]

The stent has been demonstrated to be a useful device in the treatment of complicated coronary angioplasty and in the prevention of restenosis. However, its efficacy was seen to be initially limited due to a high incidence of thrombotic occlusion of the stent in the first month after implantation and a high rate of hemorrhagic complications when a severe antithrombotic treatment with antiplatelet drugs (aspirin and dypiridomole) was associated with anticoagulation therapy with intravenous sodium heparin and dicumarol. Both phenomena increased morbidity and the post-implantation costs of stenting. The development of new strategies in stent implantation and post-implantation management have significantly reduce these complications. The objective of this study is to review the physiopathology of thrombotic occlusion following intracoronary stent implantation and the efficacy of various antithrombotic pharmacological strategies being used for its prevention. Although certain factors existing prior to implantation (thrombus, severe dissection, and the size of the vessel) augment the probability of occlusion in the stent, the result of the implantations is a good predictor of the development of this complication. Recent studies have shown that when optimal coronary stent implantation (high pressure, strict angiographic or ultrasound criteria) resulting in a minimal or absent residual stenosis and adequate apposition of the stent against the arterial wall is associated with new antithrombotic strategies, the rate of thrombotic occlusion should be less than 1.5% and the rate or hemorrhagic complications should not be greater than what has been described for conventional angioplasty. The most consolidated current antithrombotic therapy is the association of aspirin and ticlopodine which has demonstrated its efficacy in both observational and randomized studies. The combination of antiplatelet drugs and low molecular weight heparin has also demonstrated its efficacy in non-randomized studies and may constitute an alternative in some clinical or angiographic situations. The development of stents with a smaller thrombogenic surface contact with blood (made of materials which are not thrombogenic or are coated) hopefully provides another possibility for the near future. All of these advances have minimized the problem of thrombotic occlusion of the stent and have contributed to the great expansion in the use of this technique in current interventional cardiology.