Antiplatelet therapy thrombosis

One of the significant factors promoting late stent thrombosis has been found to be premature discontinuation of dual antiplatelet therapy (aspirin and clopidrogel). In an analysis of 4,666 of patients undergoing initial PCI with BMS or DES, researchers from the Duke Heart center reported that longterm risk for death and major cardiac events was significantly increased among patients in the DES... 

McFadden EP, Stabile E, Regar E, et al. Late thrombosis in drug-eluting coronary stents after discontinuation of antiplatelet therapy. Lancet 2004 364 1519-1521. 

The reported incidence of resistance to these drugs varies greatly, from less than 5% to 75%. In part this tremendous variation in incidence reflects the definition of resistance (recurrent thrombosis while on antiplatelet therapy vs in vitro testing), methods by which drug response is measured, and patient compliance. Several methods for testing aspirin and clopidogrel resistance in vitro are now FDA-approved however, their utility outside of clinical trials remains controversial. 

Antiplatelet Trialists Collaboration. Collaborative overview of randomised trials of antiplatelet therapy— III reduction in venous thrombosis and pulmonary embolism by antiplatelet prophylaxis among surgical and medical patients. BMJ. 1994 308 235-246. 

Waksman R, Ajani AE, White RL, et al. Prolonged antiplatelet therapy to prevent late thrombosis after intracoronary gamma-radiation in patients with in-stent restenosis Washington Radiation for In-Stent Restenosis Trial plus 6 months of clopidogrel (WRIST PLUS). Circulation 2001 103 2332-2335. 

Lee S-W, Park S-W, Hong M-K, et al. Triple versus dual antiplatelet therapy after coronary stenting impact on stent thrombosis. J Am Coll Cardiol 2005 46 1833-1837. 

Optimal stent implantation and new antiplatelet therapy have reduced the thrombotic complication after stent implantation, dramatically. However, thrombosis remains a challenge in some lesions and patient subgroups. As an initial and unavoidable event during stent implantation, thrombosis and platelet activation are also involved in the development of neointimal hyperplasia. Stents coated with heparin and other antithrombotic drugs have been demonstrated to decrease thrombotic complications, although their effect on neointimal hyperplasia remains uncertain. As heparin is attached to the stent surface, we divide thromboresistant stents as heparin-coated stents and drug-eluting thromboresistant stents. 

Absolute effects of ANTIPLATELET THERAPY on PULMONARY EMBOUSM In trials that sought venous thrombosis systematically... 

Patient selection is crucial in reducing rates of stent thrombosis. The SCAAR registry initially showed increased rates of stent thrombosis with DES however, as practice patterns changed, this increase disappeared and there was no difference in stent thrombosis between DES and BMS (38). Nevertheless, given these findings, the duration of dual antiplatelet therapy with clopidogrel and aspirin is recommended for at least 12 months. 

The ATLAS ACS-TIMI 46 study was a phase n dose-escalation study of the use of rivaroxaban in preventing recurrent thrombosis in patients with acute coronary syndrome [48 ]. Patients who were taking aspirin as the sole antiplatelet therapy were randomized to either placebo or rivaroxaban 5,10, or 20 mg/day, while patients who were taking dual antiplatelet therapy took either placebo or rivaroxaban 5, 10, 15, or 20 mg/day. There was a dose-related increase in the risk of clinically significant... 

DBS have reduced the occurrence of restenosis and the need of repeated revascularization procedures by 50-70% (Moses et al. 2003 Stone et al. 2004). One of the current concerns about DBS is the increase of delayed in-stent thrombosis manifesting more than 30 days after stent implantation. This late manifestation of stent thrombosis may be related to delayed endothe-lialization of the stent and typically occurs when antiplatelet therapy is discontinued. 

Antiplatelet therapy is an efficient prevention method of thrombosis and similarly for the treatment and prevention of various cardiovascular diseases (Mori et al. 2010). Mushroom substances demonstrate inhibitory activity on platelet aggregation. Some in vivo studies show that a phenolic compound called hericenone B isolated from the hedge-... 

The present investigations, although limited to the local application of fibrolase, demonstrate that under these conditions the enzyme lyses venous or arterial thrombi rapidly and with no observable systemic or hematologic side effects. In these thrombosis model systems the enzyme, either alone or in combination with antiplatelet therapy, offers a unique, safe, and specific mechanism for clot dissolution and may prove useful as a clinically effective alternative to, or for use in synergistic combination with, presently used thrombolytic agents. 

The ACCP Conference on Antithrombotic Therapy recommended against the use of aspirin as the primary method of VTE prophylaxis.2 Antiplatelet drugs clearly reduce the risk of coronary artery and cerebrovascular events in patients with arterial disease, but aspirin produces a very modest reduction in VTE following orthopedic surgeries of the lower extremities. The relative contribution of venous stasis in the pathogenesis of venous thrombosis compared with that of platelets in arterial thrombosis likely explains the reason for this difference. 

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