Frequency and efficacy of glycoprotein IIb/IIIa therapy for treatment of threatened or acute vessel closure in 1332 patients undergoing percutaneous transluminal coronary angioplasty

Utilization of eptifibatide for treatment of severe dissections as a bail-out procedure

BACKGROUND

It has been shown in several large trials that the inhibition of glycoprotein (GP) IIb/IIIa receptors of platelets can reduce the rate of ischemic complications following percutaneous transluminal coronary angioplasty (PTCA). We sought to determine the efficacy of eptifibatide in patients with severe dissections or threatened vessel closure after PTCA in small coronary arteries (< 2.5 mm).

METHODS

Eptifibatide was used in 51 patients after conventional balloon angioplasty complicated by severe dissections with or without threatened vessel occlusion. Eptifibatide was administered as a double-bolus of 180 microg/kg bodyweight, followed by a continuous infusion at a dosage of 2.0 microg/kg min over a time period of 20 h. In this situation, the implantation of a coronary stent was avoided if a prompt antegrade flow of contrast dye could be maintained.

RESULTS

Using the GP IIb/IIIa antagonist eptifibatide, it was possible to increase or to maintain antegrade blood flow in 28 (55%) patients. In 45% of the patient population, however, repeat PTCA was needed, and in four patients (7.8%) an intracoronary stent had to be implanted. During hospitalization three (6%) patients underwent target lesion revascularization (two Re-PTCAs, one coronary bypass graft operation). There were no myocardial infarctions and there was no intrahospital death. The cumulative event rate including acute and long term events was 25%.

CONCLUSIONS

The findings of our study indicate that eptifibatide is able to prevent vessel occlusion after PTCA complicated by severe dissections with or without threatened vessel occlusion associated with a low-in-hospital complication rate.

Glycoprotein receptor inhibitors in the management of acute coronary syndromes

Coronary thrombosis and the risk of clinical adverse events remains high despite considerable advances in the management of acute coronary syndromes (ACS) with the combined use of aspirin, heparin, fibrinolytic therapy, and percutaneous coronary intervention (PCI). Platelet aggregation and thrombosis play a key role in the pathogenesis of unstable coronary syndromes. Over the past several years, multiple placebo-controlled trials involving more than 50,000 ACS patients have shown that blockade of the platelet receptor glycoprotein (GP) IIb/IIIa, the final pathway in platelet aggregation, reduces the incidence of ischemic complications among patients with ACS. Three agents (abciximab, eptifibatide, and tirofiban) are currently approved for use with aspirin and heparin in the management of ACS or during percutaneous coronary intervention. They have consistently been shown to reduce the incidence of death or myocardial infarction in the ACS population including the patients not routinely scheduled for early revascularization. They provide an augmented treatment effect among high-risk ACS patients, particularly those who have a baseline troponin-t-positive status. Recently published practice guidelines have recommended their use in high-risk patients with ACS and all those undergoing PCI.

The use of the glycoprotein IIb/IIIa receptor antagonists during percutaneous coronary intervention

Coronary thrombosis is the major cause of ischemic complications during percutaneous coronary interventions (PCI). The glycoprotein (GP) IIb/IIIa receptor plays a critical role in the process of platelet thrombus formation since it serves as the final common pathway for platelet aggregation. Presently, there are three commercially available intravenous GPIIb/IIIa inhibitors that block fibrinogen binding to its receptor. These agents significantly reduce the incidence of death and nonfatal myocardial infarction at 30 days in patients undergoing percutaneous coronary revascularization. In addition, the early benefits appear to be sustained at 6 months to 1 year. Increasing evidence shows that the predominant mechanism of benefit is due to a reduction in embolization to the microcirculation that occurs during PCI. While data regarding the comparative efficacy and cost-effectiveness of these agents are scarce, the magnitude of benefit appears to be greatest for abciximab. Furthermore, a mortality benefit has been demonstrated only for abciximab. Although high risk patients reap the greatest benefit from the use of these agents, it is clear that even patients who are classified as low-to-moderate risk still derive substantial benefit from their use. Finally, evidence indicates that the majority of patients with acute coronary syndromes without ST segment elevation who are scheduled to undergo PCI should be pretreated with a GPIIb/IIIa receptor antagonist.

Evaluation of the role of abciximab (Reopro) as a rescue agent during percutaneous coronary interventions: in-hospital and six-month outcomes

Abciximab is effective for the prevention of complications when administered prior to percutaneous coronary intervention (PCI). The efficacy and safety of abciximab as an unplanned or rescue agent for complications of PCI is unknown. Rescue versus planned use was compared in 186 consecutive patients. Primary or rescue PCI for acute myocardial infarction (MI) and shock were excluded. Rescue abciximab use was undertaken in 101 patients (54.3%) and planned abciximab was used in 85 (45.7%). The rescue abciximab patients had a lower incidence of previous MI, preprocedural thrombus, multivessel, and vein graft intervention. In-hospital endpoints in the rescue versus planned abciximab patients were death (1.0% vs. 1. 2%, P = 1.0), Q-wave MI (2.0% vs. 2.4%, P = 1.0), any MI (14.9% vs. 9.4%, P = 0.3), target vessel revascularization (TVR; 0% vs. 1.2%, P = 1.0), and composite (15.8% vs. 10.6%, P = 0.3). At 6 months, events were death (4.0% vs. 2.3%, P = 0.69), MI (14.9% vs. 9.4%, P = 0.26), TVR (20.8% vs. 4.7%, P = 0.001), and composite (30.7% vs. 15. 3%, P = 0.01). In-hospital complications between the rescue and planned abciximab patients of major bleed (1.0% vs. 1.8%, P = NS), stroke (0% vs. 1.8%, P = NS), and thrombocytopenia (3.0% vs. 1.8%, P = NS) were similar. There was a significantly higher procedural time (99.6 min vs. 86.1 min, P = 0.02), contrast volume (278.8 ml vs. 223. 5 ml, P = 0.04), and heparin use (8984 u vs. 6003 u, P = 0.0006) in the rescue group. In this nonrandomized comparison, rescue abciximab allowed for the safe discharge from hospital in the majority of patients. However, during a 6-month follow-up, more patients treated with rescue abciximab required TVR with either repeat PCI or CABG. Further studies are warranted to evaluate the overall strategy of rescue abciximab use in PCI.

Estudo experimental do uso de um antagonista do receptor da glicoproteína IIb/IIIa das placentas na prevenção de tromboses em microanastomoses vasculares

O autor comparou, experimentalmente, a eficácia da droga abciximab, um antagonista do receptor da glicoproteína IIb/IIIa das plaquetas, na prevenção da trombose nas microanastomoses arteriais em ratos Wistar. Utilizou 20 animais, dos quais 10, do grupo controle, receberam solução salina e 10 receberam abciximab, na concentração de 0,8mg/kg, injetados na veia femoral. Trinta minutos após a administração da solução salina ou abciximab, todos os animais foram submetidos ao mecanismo provocador de trombose vascular da artéria femoral do lado oposto ao utilizado para administração da droga, por meio de um trauma externo promovido por aparelho IMPACTOR, desenvolvido pela New York University para padronização de lesão da medula nervosa, o que padronizou a lesão arterial. Todos os animais foram submetidos à microanastomose vascular com mononáilon 10-0, em pontos separados, no local do trauma externo. Foram realizados testes para analisar a perviabilidade vascular da artéria femoral no período de 10, 20 e 30 minutos após o término da anastomose. Após este período, todas as artérias femorais submetidas às microanastomoses foram ressecadas e analisadas em microscopia óptica para avaliar a presença de formação de trombos. Após a análise estatística dos dados, o autor concluiu que o uso do antagonista do receptor da glicoproteína IIb/IIIa das plaquetas diminuiu a incidência de tromboses nas microanastomoses vasculares.

Ischemic complications after percutaneous transluminal coronary angioplasty

The ischemic complications ofpercutaneous transluminal coronary angioplasty (PTCA) include abrupt closure, which occurs in 2% to 10% of patients and is associated with increased morbidity and mortality. Periprocedural myocardial infarction due to side branch occlusion or embolization of platelet aggregates or thrombus occurs in 5% to 20% of patients. Patients with acute coronary syndromes, older age, and complex lesions are at greater risk of periprocedural complications. Technical advances, primarily stenting, are useful in the prevention and management of acute closure, but are also accompanied by thrombotic complications. It remains to be seen whether the new antithrombin agents reduce the rate of periprocedural complications if used in combination with aspirin and new antiplatelet therapies. These new antiplatelet agents (ticlopidine, clopidogrel, abciximab, eptifibatide, and tirofiban) reduce the rate of ischemic complications and have become standard adjunctive therapy for patients who undergo PTCA.