Prior aspirin users with acute non-ST-elevation coronary syndromes are at increased risk of cardiac events and benefit from enoxaparin.

BACKGROUND: The aim of this article was to investigate whether prior aspirin use in patients with acute coronary syndromes affects clinical outcome. The Efficacy Safety Subcutaneous Enoxaparin in Non-Q-Wave Coronary Events Study (ESSENCE) and Thrombolysis in Myocardial Infarction (TIMI) 11B trials have shown superiority of enoxaparin over unfractionated heparin (UFH) in patients with unstable angina and non-ST-segment elevation myocardial infarction (UA/NSTEMI). However, the treatment effect of enoxaparin in the subset of patients reporting prior aspirin use has not been determined. METHODS: The rate of death, myocardial infarction, and urgent revascularization at days 8 and 43 after randomization was compared among patients who received aspirin within the week before randomization with those who did not receive aspirin in the TIMI 11B trial. A total of 3275 patients (84%) were prior aspirin users. RESULTS: The admission diagnosis was similar for prior and nonprior aspirin users. At both day 8 and day 43 the event rate was higher for prior aspirin users than for nonprior aspirin users (odds ratio 1.6 [1.24-2.08], P =.0004 at day 43), even after correction for baseline characteristics. Compared with those prior aspirin users taking UFH, enoxaparin-treated prior aspirin users had a reduced rate of the composite end point of death, myocardial infarction, and urgent revascularization at day 8 (odds ratio 0.82 [0.67-1.00], P =.046) and day 43 (odds ratio 0.83 [0.70-0.98], P =.032). CONCLUSION: Patients with UA/NSTEMI and prior aspirin use had a 60% higher risk of death and cardiac ischemic events compared with nonprior aspirin users. On the basis of this subanalysis, enoxaparin is superior to UFH in all patients. In prior aspirin users the benefit is more clearly demonstrated.

Superiority of enoxaparin versus unfractionated heparin for unstable angina/non-Q-wave myocardial infarction regardless of activated partial thromboplastin time.

BACKGROUND: Whether the clinical superiority of enoxaparin versus unfractionated heparin (UFH) depends on a more stable antithrombotic effect or the proportion of patients not reaching the therapeutic level with UFH has not been addressed. METHODS: All patients participating in the Thrombolysis In Myocardial Infarction 11B trial who received UFH and had sufficient activated partial thromboplastin time (aPTT) data (n = 1893) were compared with patients who received enoxaparin (n = 1938). Patients receiving UFH were divided into 3 categories depending on mean aPTT values throughout 48 hours: subtherapeutic, for those in whom the average aPTT fell below 55 seconds; therapeutic, between 55 and 85 seconds; and supratherapeutic, longer than 85 seconds. Events and bleeding rates were determined at 48 hours. RESULTS: A small portion of patients (6. 7%) had a subtherapeutic average aPTT value (n = 127). Forty-seven percent of patients (n = 891) fell within the therapeutic range, and 46% were in the supratherapeutic level (n = 875). Event rates were 7. 0% in the UFH group versus 5.4% with enoxaparin (P =.039). Events rates were higher in every aPTT strata compared with enoxaparin and statistically significant in the supratherapeutic group (odds ratio 0.65; 95% confidence interval, 0.47-0.89). Major bleeding rates were 0%, 0.6%, and 0.9% for the subtherapeutic, target, and supratherapeutic strata, respectively, and 0.8% with enoxaparin. Minor hemorrhages occurred in 5.1% of patients receiving enoxaparin versus 3.9%, 2%, and 2.3%, respectively, for the UFH subgroups (P <. 001 for all UFH groups vs enoxaparin). CONCLUSIONS: Enoxaparin showed a better clinical profile compared with every level of anticoagulation with UFH. Potential mechanisms for enoxaparin superiority are stable antithrombotic activity, lack of rebound thrombosis, and intrinsic superiority.

Low-molecular-weight heparin alone versus a combination of unfractionated heparin and low-molecular-weight heparin.

OBJECTIVES: We analyzed the effect of the pharmacologic combination of 2 indirect antithrombin drugs--enoxaparin (low-molecular-weight heparin) and unfractionated heparin--versus enoxaparin alone on the recurrence of ischemia. BACKGROUND: Blocking some key factors of the coagulation cascade supports the concept that an antithrombin effect is needed during the acute phase of ischemia. METHODS: This was a prospective, randomized, pilot trial in patients with an acute coronary ischemic event occurring within the previous 24 hours. A total of 126 patients were allocated to receive aspirin (200 mg/day orally) plus 1 mg/kg subcutaneous enoxaparin at 8 AM and 12.500 IU of subcutaneous unfractionated heparin at 8 PM (group A) or subcutaneous enoxaparin 1 mg/kg (group B). RESULTS: Severe recurrent ischemia provoking urgent coronary revascularization occurred in 12 patients (9.5%), 3 (5%) in group A and 9 (13%) in group B (P = .1). Refractory angina was present in 27 patients (21%), 10 (17%) in group A and 17 (25%) in group B (P = .45). The combination of severe recurrent ischemia and refractory angina occurred in 23% of group A, and 37% of group B (odds ratio 0.49; 95% confidence intervals, 0.21-1.15; P = .07). A total of 7 patients (5%) had acute nonfatal myocardial infarction develop, 3 (5%) in group A and 4 (6%) in group B. Two (1.6%) deaths were observed in the study, both in group B. The incidence of the double end point (death plus nonfatal myocardial infarction) was 5% in group A versus 9% in group B (P = .5) and the triple end point (death, nonfatal myocardial infarction, and severe recurrent ischemia) was 10.5% in group A vs 22% in group B (odds ratio 0.42, 95% confidence intervals, 0.13-1.29; P = .09). CONCLUSIONS: The combination of 2 indirect antithrombin drugs capable of intermittently blocking the coagulation system is not associated with a significant loss of safety.