Efficacy and Safety of Subcutaneous Enoxaparin in Unstable Angina and Non-Q-wave MI - ESSENCE


Enoxaparin vs. heparin in unstable angina and non-Q-wave MI.


Effectiveness of enoxaparin versus unfractionated heparin in patients with unstable angina and non-Q-wave MI.

Study Design

Study Design:

Patients Screened: Not given
Patients Enrolled: 3,171
Mean Follow Up: 1 year
Mean Patient Age: 64
Female: 34

Patient Populations:

Men or nonpregnant women at least 18 years of age
Angina at rest lasting at least 10 minutes and occurring within 24 hours before randomization.
Evidence of underlying ischemic heart disease by EKG, history, or noninvasive/invasive testing


Left bundle-branch block
Persistent ST-segment elevation
Angina with an established precipitating cause (e.g., heart failure or tachydysrhythmia)
Contraindications to anticoagulation
Creatinine clearance rate of less than 30 ml /min

Primary Endpoints:

Composite of recurrent angina (leading to rehospitalization or revascularization), myocardial infarction (CK/MB elevation/new Q-waves), and death at 14 days

Secondary Endpoints:

Triple composite end point at 48 hours and 30 days
Double composite end point (death or myocardial infarction) at 48 hours, 14 days, and 30 days.
Incidence of major and minor hemorrhage was tabulated

Drug/Procedures Used:

1 mg/kg subcutaneous enoxaparin bid for 2-8 days (mean 2.6 days) vs intravenous dose-adjusted unfractionated heparin

Concomitant Medications:


Principal Findings:

At 14 days the risk of death, myocardial infarction, or recurrent angina was significantly lower in patients assigned to enoxaparin than in those assigned to unfractionated heparin (16.6% vs. 19.8%, P = 0.019).

At 30 days, the composite end point remained significantly lower in the enoxaparin group (19.8% vs. 23.3%, P = 0.016). The need for revascularization procedures at 30 days was also significantly less frequent in patients assigned to enoxaparin (27.0% vs. 32.2%, P = 0.001).

The 30-day incidence of major bleeding complications was 6.5% in the enoxaparin group and 7.0% in the unfractionated-heparin group. The incidence of bleeding overall was significantly higher in the enoxaparin group (18.4 percent vs. 14.2%, P = 0.001), primarily because of ecchymoses at injection sites.
One-year follow-up was 92% complete (1607 patients in the enoxaparin group and 1564 patients in the unfractionated heparin group). The risk of death, MI, or recurrent angina was significantly lower for the enoxaparin group (35.7% heparin vs 32.0% enoxaparin).

For the secondary endpoint of death/MI, was a trend favoring enoxaparin at 30 days (7.7% heparin vs. 6.2% enoxaparin). The relative benefit was sustained at 1 year (13.5% heparin vs 11.5% enoxaparin).

At one year, the requirement for a diagnostic catheterization was significantly lower (59.4% for the UFH group and 55.8% for the enoxaparin group), as was the incidence of coronary revascularization (41.2% for the UFH group and 35.9% for the enoxaparin group).


The ESSENCE study shows that the use of enoxaparin significantly reduces the triple endpoint (death, MI, recurrent angina) at 30 days in patients with unstable angina and non-Q-wave MI. The early benefit is sustained at 1 year, and it is obtained without an increase in major hemorrhagic events, though with a very small increase in minor hemorrhagic events, mainly at injection sites and puncture sites. The ESSENCE investigators concluded that treatment with enoxaparin plus aspirin should be considered for at least 48 hours in patients with unstable angina or non-Q-wave MI to reduce the short-term and long-term risk of recurrent angina, MI, or death. Enoxaparin can be simply administered without need for anticoagulation monitoring, which leads to cost savings and superior short-term and sustained long-term efficacy.


1. N Engl J Med 1997;337:447-52. Final results
2. Eur Heart J 1998;19(Abstr Suppl):50. One-year follow-up

Keywords: Myocardial Infarction, Follow-Up Studies, Research Personnel, Enoxaparin, Ecchymosis, Catheterization, Heparin, Cost Savings, Electrocardiography

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