Session highlights from the American Heart Association Scientific Sessions: November 9-12, 1997

An audit of the use and complications of glycoprotein IIb/IIIa inhibitors in percutaneous coronary intervention against national UK standards

Coronary thrombosis is a pivotal event in the pathogenesis of acute coronary syndromes and ischemic complications resulting from coronary intervention. Activation of the platelet glycoprotein (GP) IIb/IIIa receptor is the final common pathway leading to platelet aggregation, coronary thrombus formation, and myocardial ischemia. Inhibitors of platelet GP IIb/IIIa are potent agents to prevent progression to myocardial infarction and death. We prospectively surveyed the indications, frequency, and complications associated with the use of GP IIb/IIIa inhibitors in percutaneous coronary intervention in a tertiary center setting. A total of 170 patients underwent screening over a period of 6 weeks. One hundred four (61%) had coronary intervention, out of which eight (8%) had failed intervention. Glycoprotein IIb/IIIa inhibitors were used in 57 (55%) patients; 47 (45%) did not have any agent periprocedure. Eptifibatide was the most commonly used agent in 35 (33%), followed by abciximab in 19 (18%) and tirofiban in 3 (3%). Out of 57 patients in whom GP IIb/IIIa agents were used, 22 (38%) had visible intracoronary thrombus, 22 (38%) had diffuse disease, 8 (14%) had complex intervention, and 5 (9%) had diabetes. The overall incidence of complications was not increased by the use of GP IIb/IIIa inhibitors; serious complications were rare with the use of GP IIb/IIIa agents; no stroke, thrombocytopenia, gastrointestinal bleed, or death was recorded. The overall use in emergency settings was not associated with increased complications. Bradycardia and vomiting were more common with abciximab group, whereas puncture site pain was commoner in eptifibatide group.

Dofetilide: a new pure class III antiarrhythmic agent

BACKGROUND

Although there are a variety of antiarrhythmic agents used for the treatment of atrial fibrillation of flutter, each drug has drawbacks, and room exists for new pharmacologic agents. Dofetilide, a pure class III agent, has recently been approved by the Food and Drug Administration for therapy of these arrhythmias and is reviewed.

METHODS

Data for dofetilide, published in full or in abstract form, were reviewed, concentrating on the properties related to its efficacy for the therapy of supraventricular arrhythmias.

RESULTS

Results from animal and human studies indicate that dofetilide, a renally excreted drug, has pure class III properties related to blockade of the delayed rectifier potassium current. It is effective for the therapy of atrial arrhythmias, particularly atrial fibrillation and flutter, and has no demonstrable negative inotropic effect. Despite an incidence of torsades de pointes of approximately 2% in patients with impaired ventricular function, dofetilide exhibited no association with an increased mortality rate when studied in a large series of patients with a reduced ejection fraction.

CONCLUSIONS

Dofetilide's electrophysiologic and clinical profiles suggest that it will be safe and clinically useful for the termination and prevention of atrial fibrillation or flutter, even in patients with impaired ventricular function.

The duration of pretreatment with ticlopidine prior to stenting is associated with the risk of procedure-related non-Q-wave myocardial infarctions

OBJECTIVES

This study sought to determine whether the duration of pretreatment with the adenosine diphosphate receptor antagonist ticlopidine prior to intracoronary stenting is associated with the incidence of procedure-related non-Q-wave myocardial infarctions (MIs).

BACKGROUND

Dual antiplatelet therapy with ticlopidine and aspirin is routinely used with stenting, although ticlopidine is commonly not begun until the day of the procedure. Periprocedural MIs are at least partially platelet-dependent events. As the maximal platelet inhibitory effects of this drug take 2 to 3 days to be realized, we hypothesized that longer treatment prior to stenting would be associated with lower rates of procedure-related MIs.

METHODS

We reviewed outcomes in 175 consecutive patients treated with ticlopidine prior to stenting at the Cleveland Clinic Foundation. Those patients with an elevation in creatine kinase above our laboratory normal (>210 IU/L) with > or =4% MB fraction on routine evaluation were defined as having a non-Q-wave MI. RESULTS. There were 28 patients (16%) who had a non-Q-wave MI. Longer duration of ticlopidine pretreatment was strongly associated with a lower incidence of procedure-related non-Q-wave MIs (duration of pretreatment <1 day, 29% had MI; 1 to 2 days, 14%; > or =3 days, 5%; chi-square for trend=9.6; p=0.002). Ticlopidine pretreatment of > or =3 days was associated with a significant reduction in the risk of non-Q-wave MI (unadjusted odds ratio 0.18, 95% confidence interval=0.04 to 0.78, p=0.01) compared with pretreatment of <3 days.

CONCLUSIONS

Among patients undergoing intracoronary stenting, beginning ticlopidine therapy several days prior to the procedure is associated with a reduced risk of procedural non-Q-wave MIs.

Inhibition of platelet glycoprotein IIb/IIIa with eptifibatide in patients with acute coronary syndromes

BACKGROUND

Aggregation of platelets is the pathophysiologic basis of the acute coronary syndromes. Eptifibatide, a synthetic cyclic heptapeptide, is a selective high-affinity inhibitor of the platelet glycoprotein IIb/IIIa receptor, which is involved in platelet aggregation. We tested the hypothesis that inhibition of platelet aggregation with eptifibatide would have an incremental benefit beyond that of heparin and aspirin in reducing the frequency of adverse outcomes in patients with acute coronary syndromes who did not have persistent ST-segment elevation.

METHODS

Patients who had presented with ischemic chest pain within the previous 24 hours and who had either electrocardiographic changes indicative of ischemia (but not persistent ST-segment elevation) or high serum concentrations of creatine kinase MB isoenzymes were enrolled in the study. They were randomly assigned, in a double-blind manner, to receive a bolus and infusion of either eptifibatide or placebo, in addition to standard therapy, for up to 72 hours (or up to 96 hours, if coronary intervention was performed near the end of the 72-hour period). The primary end point was a composite of death and nonfatal myocardial infarction occurring up to 30 days after the index event.

RESULTS

A total of 10,948 patients were enrolled between November 1995 and January 1997. As compared with the placebo group, the eptifibatide group had a 1.5 percent absolute reduction in the incidence of the primary end point (14.2 percent, vs. 15.7 percent in the placebo group; P=0.04). The benefit was apparent by 96 hours and persisted through 30 days. The effect was consistent in most major subgroups except for women (odds ratios for death or nonfatal myocardial infarction, 0.8 [95 percent confidence interval, 0.7 to 0.9] in men, and 1.1 [0.9 to 1.31 in women). Bleeding was more common in the eptifibatide group, although there was no increase in the incidence of hemorrhagic stroke.

CONCLUSIONS

Inhibition of platelet aggregation with eptifibatide reduced the incidence of the composite end point of death or nonfatal myocardial infarction in patients with acute coronary syndromes who did not have persistent ST-segment elevation.