Subacute stent thrombosis: Evolving issues and current concepts

Abstract

During percutaneous coronary revascularization, intracoronary stents are effective in the treatment of abrupt vessel closure and improvement of suboptimal angioplasty results, and compared to balloon angioplasty, they reduce stenosis recurrence. Opposing these benefits, subacute thrombosis of stents is associated with a substantial increase in periprocedural morbidity and mortality. To review factors associated with stent thrombosis and to study the impact of evolving procedural techniques on the incidence of stent thrombosis, we reviewed all English articles from MEDLINE (1988 to 1995) with key words "stent" and "thrombosis." Stent registry data and recent abstracts from scientific meetings were also reviewed. Factors related to the clinical setting, the lesion, the stent and the procedural technique that affect the risk of stent thrombosis were identified. Sixty clinical studies were reviewed and include 7,914 patients receiving intracoronary stents. Studies were separated into those reporting stents placed emergently or electively without adjunct high-pressure balloon inflations, stents placed in saphenous vein graft conduits, and stents placed with high-pressure balloon inflations but without subsequent oral anticoagulants. Overall, subacute thrombosis was substantially higher in stents placed emergently (10.1%) compared to those placed electively (4.3%). Among contemporary trials employing high-pressure balloon inflations, the rate of stent thrombosis appears markedly lower (1.3%) despite reduced postprocedural anticoagulation. Taken together, these studies suggest factors associated with a heightened risk of stent thrombosis, many of which can be avoided with proper case selection and contemporary techniques.

Randomized Multicenter Comparison of Conventional Anticoagulation Versus Antiplatelet Therapy in Unplanned and Elective Coronary Stenting

“…They further demonstrated that high pressure-assisted stent implantation accomplished without intravascular ultrasound guidance and subsequent anticoagulation was safe and associated with a low risk of subacute stent occlusion. 4 In a recent pooled analysis, 8 stentrelated thrombosis occurred in only 33 of 2630 patients who did not receive anticoagulant therapy. The majority of the patients in this report did not have ultrasound-guided stent implantation whereas high-pressure inflation was commonly used.…”

Treatment of Intracoronary Thrombus Using Tirofiban in a Patient With Normal Coronary Arteries

“…[1][2][3][4][5][6] However, an ICT or myocardial infarction with normal coronary arteries is a syndrome resulting from numerous conditions, but the exact cause in a majority of patients remains unknown. Possible mechanisms include embolism, vasospasm, nonatherosclerotic coronary diseases, hypercoagulable states, trauma, an imbalance between oxygen demand and supply, intense sympathetic stimulation, and endothelial dysfunction.…”

Stents. Uma revisão da literatura

“…Havia a suspeita de que o stent, por sua constituição metálica, fosse intrinsicamente trombogênico, atribuindo-se a ele comportamento semelhante às próteses valvares 22 . Em conseqüên-cia, estabeleceram-se regimes intensos de anticoagulação, com heparina, dextran, ácido acetil-salicílico, dipiridamol e cumarínico 23 . A ocorrência de TSA apesar de anticoagulação ótima fez Colombo e col, em 1995, teorizarem que a chave para evitá-la não era o controle ótimo da hemostasia, mas o implante ótimo da prótese, com a normalização da reologia intra-stent e do afluxo e efluxo sangüíneo 24 .…”

“…Iniciava-se assim a fase de implante ótimo de stents, técnica ainda vigente. Reduziu-se a taxa de complicações vasculares e hemorrágicas de 10 a 15% para 2 a 3%, e a de TSA, de 4 a 10% para 1 a 1,5% 23,29 , com diminuição dos períodos de internação e de custos.…”

“…Esta nova estratégia inaugurou uma nova era no implante de stents: a era do implante óti-mo, que se baseia em atingir uma luz de calibre uniforme com as referências, usando hiperinsuflações com balões não-complascentes ajustados para o calibre do segmento normal do vaso 24 . Fatores de risco para TSA após stent nesta nova fase incluem: síndromes coronárias agudas, vasos pequenos, lesão ostial, doença distal, presença de trombo intracoronário ou dissecção residual, múltiplos stents por lesão, oclusão total, presença de circulação colateral e vaso suprindo miocárdio acinético ou severamente hipocinético 23,110 . Seguiram-se vários estudos que visavam determinar a segurança e viabilidade das novas abordagens.…”