Defining the role of abciximab for acute coronary syndromes: lessons from CADILLAC, ADMIRAL, GUSTO IV, GUSTO V, and TARGET

Review: The management of acute myocardial infarction in patients with diabetes mellitus

Diabetic subjects are more likely to experience a myocardial infarction and have worse outcomes compared to non-diabetic subjects. The underlying pathophysiology of the atherosclerotic process is not significantly different in diabetic subjects, but the prothrombotic and procoagulant state with which diabetes is associated is thought to contribute to the higher incidence of and worse prognosis after myocardial infarction. Difficulties of re-establishing vessel patency by thrombolytic or mechanical means contribute to the high morbidity and mortality. The diffuse nature of arterial disease with accompanying metabolic derangement contribute to impaired compensatory mechanisms, increased infarct size and a disproportionately more substantial impairment of left ventricular function. The newer adjuvant antithrombotic and anticoagulant agents have particular roles in management therefore and careful modulation of glucose metabolism in the acute and follow-up phase of an infarct may favourably influence outcome.

Transregulation of the alpha2-adrenergic signal transduction pathway by chronic beta-blockade: a novel mechanism for decreased platelet aggregation in patients

Platelets play a pivotal role in the pathophysiology of acute coronary syndromes. Chronic beta-blockade has been shown to improve the long-term clinical outcome in coronary heart disease. Because platelets play a central role in thrombus formation, the aim of the present study was to investigate if chronic beta-blockade may transregulate the expression of alpha2-adrenergic receptors on human platelets and via this mechanism may modulate platelet activation. The densities of alpha2-adrenergic receptors of platelets were determined in healthy volunteers under chronic beta-blockade and as alpha2-adrenergic receptor-mediated function in catecholamine-induced platelet aggregation was determined. Chronic beta-blockade induced a time-dependent reduction of alpha2-adrenergic receptors. This reduction was accompanied by a decrease of the alpha-subunit of Gi proteins as demonstrated by Western blot analysis. This transregulation at both the receptor level and the G-protein level resulted in an almost complete loss of the alpha2-adrenergic receptor-mediated inhibition of adenylyl cyclase. The impairment of the alpha2-adrenergic receptor system correlated with a reduction of the catecholamine-induced activation and aggregation of human platelets. The functional transregulation of alpha2-adrenergic receptors by chronic beta-blockade in platelets and the consequent impairment of platelet activation may contribute to the therapeutic success of beta-blocker therapy.

Catheter-Directed Intra-Arterial Abciximab Administration for Acute Thrombotic Occlusions during Neurointerventional Procedures

SUMMARY

Abciximab is one of a new class of platelet aggregation inhibitors that has to date been used mainly in the management of acute coronary ischaemic syndromes or during cardiac intervention for the prevention and treatment of acute vessel occlusion during and after angioplasty or stent placement. More recently, it has begun to play a similar role in neurointerventional work. Its administration during acute stent or vessel occlusions has usually been via systemic intravenous infusion.We describe five cases of acute vessel occlusion during neurointerventional procedures where the abciximab bolus was administered intra-arterially at or close to the site of the occlusion, with rapid complete visual dissolution of the thrombus in four cases and partial dissolution in one, resulting in two patients with no neurological deficits, one with no further neurological deterioration, one with a mild residual thumb paresis and one with a severe neurological deficit.

Abciximab: an updated review of its therapeutic use in patients with ischaemic heart disease undergoing percutaneous coronary revascularisation

Abciximab (Reopro) is an antibody fragment that dose-dependently inhibits platelet aggregation and leucocyte adhesion by binding to the glycoprotein (GP) IIb/IIIa, vitronectin and Mac-1 receptors. Abciximab (0.25 mg/kg bolus plus infusion of 0.125 micro g/kg/min for 12 hours) showed greater efficacy than tirofiban in reducing the 30-day composite endpoint of death, nonfatal myocardial infarction (MI) or urgent target-vessel revascularisation in the randomised, double-blind TARGET study in patients scheduled for stent placement. In addition, the beneficial effects of treatment with abciximab previously observed in the randomised, multicentre, placebo-controlled EPILOG and EPISTENT studies have been maintained to 1 year, with a significantly reduced incidence of ischaemic complications relative to placebo consistently observed across a range of subgroups including age, sex, bodyweight and indication for revascularisation. The incidence of the composite endpoint was reduced in patients presenting with acute MI of <48 hours' duration in comparison with either fibrinolytic therapy or stenting alone in the randomised STOPAMI and ADMIRAL trials, primarily because of a reduced requirement for urgent repeat revascularisation and reduced incidence of mortality. In the randomised, nonblind, multicentre CADILLAC trial in patients with acute myocardial infarction (MI), stenting alone was superior to percutaneous transluminal coronary angioplasty (PTCA) and stenting alone was not inferior to PTCA plus abciximab. Recent large randomised, multicentre studies (ASSENT-3 and GUSTO-V) have shown higher efficacy (on various ischaemic endpoints) of abciximab in combination with either a reduced dose of tenecteplase or reteplase compared with the fibrinolytic drug alone. TIMI grade 3 flow rates at 60 and 90 minutes in the TIMI-14 and SPEED trials were higher in patients who received abciximab in combination with either alteplase or reteplase than abciximab alone and were similar to that seen with the full-dose fibrinolytic alone. In the randomised, multicentre GUSTO IV-ACS study, no significant differences in any of the ischaemic endpoints at either 7 or 30 days in patients with acute coronary syndromes who were not scheduled to undergo early revascularisation (within 12 hours of end of infusion) were apparent between those who received abciximab (bolus and either 24- or 48-hour infusion) and those who received placebo in addition to aspirin and heparin. The most common adverse events associated with the use of abciximab are bleeding complications and thrombocytopenia, although the risk of major bleeding can be limited through adhering to current administration protocols. Treatment costs are generally higher in both stent plus abciximab and angioplasty plus abciximab groups than stent plus placebo, primarily because of the acquisition cost of abciximab. Abciximab appeared most cost beneficial in high-risk patients undergoing elective percutaneous coronary revascularisation; among lower risk patients, abciximab therapy has been associated with higher total in-hospital and 6-month medical costs than eptifibatide.

CONCLUSION

The GP IIb/IIIa receptor antagonist abciximab, when used with aspirin and heparin, has demonstrated efficacy in reducing the short- and long-term risk of ischaemic complications in patients with ischaemic heart disease undergoing percutaneous coronary intervention, when used with aspirin and heparin. High-risk patients (including those with diabetes mellitus) derive particular benefits from abciximab treatment. Abciximab remains an important therapeutic option for the prevention of complications in patients with ischaemic heart disease.

Current therapy of the right ventricle myocardial infarction

BACKGROUND

Acute myocardial infarction of the right ventricle (AMI-RV) is a separate subgroup within the scope of inferoposterior infarction of the left ventricle. It still represents the population of patients at high risk due to numerous, often hardly predictable complications and high mortality rate.

METHODS

In fifteen-year period (1987-2001) 3,765 patients with the acute myocardial infarction (AMI) of different localizations of both sexes--2,283 males and 1,482 females of the average age 61.4 +/- 4.6 years were treated in our institution. Anterior myocardial infarction was diagnosed in 2,146 (56.9%) patients, inferior in 1,619 (43.1%) patients, out of whom right ventricular infarction (RVI) was confirmed in 384 (23.7%). Thrombolytic therapy was administered in 163 (42.4%) patients with RVI, and in 53 (41.7%) of these patients balloon dilatation was performed with coronary stent implantation in 24 (45.2%).

RESULTS

Favorable clinical effect of the combined thrombolytic therapy and percutaneous transluminal coronary angioplasty (PTCA) was achieved in 51 (96.1%), and in only 2 (3.9%) of patients the expected effect wasn't achieved. Myocardial revascularization was accomplished in 6 (3.6%) and 1 patient died. In 3 (3.4%) patients primary balloon dilatation with the implantation of intracoronary stent was performed within 6 hours from the onset of anginal pain. In the other group of 221 (57.5%) patients with RVI who did not receive thrombolytic therapy, or it had no effect, 26 (11.7%) patients died, which indicated the validity and the efficacy of this treatment (p < 0.01). In the whole group of patients with myocardial infarction of the right ventricle 31 (8.1%) died; in the group that received thrombolytic therapy and PTCA 5 (3.1%) died, while in the group treated in a conservative way 26 (11.7%) died.

CONCLUSION

Combined therapy was successful in the treatment of patients with RVI and should be administered whenever possible, since it was the best prevention of life-threatening complications and the decrease in the mortality of those patients.