Percutaneous coronary intervention in patients receiving enoxaparin or unfractionated heparin after fibrinolytic therapy for ST-segment elevation myocardial infarction in the ExTRACT-TIMI 25 trial.

OBJECTIVES: We sought to evaluate whether enoxaparin (ENOX) is superior to unfractionated heparin (UFH) as adjunctive therapy for patients with ST-segment elevation myocardial infarction (STEMI) who receive fibrinolytic therapy and subsequently undergo percutaneous coronary intervention (PCI) by analyzing data from the ExTRACT-TIMI 25 (Enoxaparin and Thrombolysis Reperfusion for Acute Myocardial Infarction Treatment-Thrombolysis In Myocardial Infarction 25) trial. BACKGROUND: Limited data are available on the use of ENOX compared with UFH as adjunctive therapy in STEMI patients treated with fibrinolytic therapy and subsequent PCI. METHODS: A total of 20,479 STEMI patients who received fibrinolytic therapy were randomized to a strategy of ENOX throughout index hospitalization or UFH for at least 48 h, with blinded study drug to continue if PCI was performed. The primary end point of death or recurrent MI through 30 days was compared for ENOX versus UFH among the patients who underwent subsequent PCI (n = 4,676). RESULTS: After initial fibrinolysis, fewer patients underwent PCI through 30 days in the ENOX versus the UFH group (22.8% vs. 24.2%; p = 0.027). Among patients who underwent PCI by 30 days, the primary end point occurred in 10.7% of ENOX and 13.8% of UFH patients (0.77 relative risk; p < 0.001). There were no differences in major bleeding for ENOX versus UFH (1.4% vs. 1.6%; p = NS). Results were similar when PCI was carried out in patients receiving blinded study drug during PCI (n = 2,178). CONCLUSION: Among patients treated with fibrinolytic therapy for STEMI who underwent subsequent PCI, ENOX administration was associated with a reduced risk of death or recurrent MI without difference in the risk of major bleeding. The strategy of ENOX support for fibrinolytic therapy followed by PCI is superior to UFH and provides a seamless transition from the medical management to the interventional management phase of STEMI without the need for introducing a second anticoagulant in the cardiac catheterization laboratory.     

The impact of renal dysfunction on outcomes in the ExTRACT-TIMI 25 trial.

OBJECTIVES: The ExTRACT-TIMI 25 (Enoxaparin and Thrombolysis Reperfusion for Acute Myocardial Infarction Treatment-Thrombolysis In Myocardial Infarction 25) trial provided the opportunity to evaluate the impact of renal dysfunction on outcomes in patients with ST-segment elevation myocardial infarction (STEMI) and compare enoxaparin (ENOX) and unfractionated heparin (UFH). BACKGROUND: It is unclear how renal dysfunction influences the balance between benefit and risk of antithrombotic therapy. METHODS: In the ExTRACT-TIMI 25 trial, 20,479 patients were randomized to UFH or ENOX. A reduced ENOX dose was administered to patients age > or =75 years and those with an estimated creatinine clearance (CrCl) <30 ml/min. RESULTS: A powerful relationship was observed between the severity of renal dysfunction (per 10 ml/min decrement in CrCl) and death, stroke, intracranial hemorrhage, and major and minor bleeding (p < 0.001 for each). There was a progressive increase in the treatment benefit with ENOX on death or nonfatal myocardial infarction (p < 0.01) with better renal function. Net clinical benefit (death, nonfatal MI, or nonfatal major bleeding) was significantly superior with ENOX (p < 0.001) for patients with a CrCl >60 ml/min (79.1% of the study population). Major bleeding and intracranial hemorrhage did not differ for patients with preserved renal function (CrCl >90 ml/min), but in those with renal dysfunction there was a progressively greater increase in the risk of major and minor bleeding with ENOX. CONCLUSIONS: Enoxaparin was superior to UFH for the majority of subjects. With more severe renal dysfunction, the net clinical benefit between ENOX and UFH did not differ, despite the rise in adverse events in both treatment groups. Future studies should take renal dysfunction into account when assessing antithrombotic regimens.     

Enoxaparin is superior to unfractionated heparin in patients with ST elevation myocardial infarction undergoing fibrinolysis regardless of the choice of lytic: an ExTRACT-TIMI 25 analysis.

AIMS: We compared outcomes of ST-elevation myocardial infarction (STEMI) patients randomized to a strategy of either enoxaparin or unfractionated heparin (UFH) to support fibrinolysis. METHODS AND RESULTS: In the Enoxaparin and Thrombolysis Reperfusion for Acute Myocardial Infarction Treatment-Thrombolysis in Myocardial Infarction Study 25 (ExTRACT-TIMI 25) trial, 20,479 patients undergoing fibrinolysis for STEMI with a fibrin-specific agent (N = 16,283) or streptokinase (SK) (N = 4139) were randomized to enoxaparin throughout their hospitalization or UFH for at least 48 h. The primary end point of death or nonfatal recurrent MI through 30 days occurred in 12.0% of patients in the UFH and 9.8% in the enoxaparin groups when treated with fibrin-specific lytics [odds ratio(adjusted) (OR(adj)) 0.78; 95% CI 0.70-0.87; P < 0.001] and 11.8 vs. 10.2%, respectively, when treated with SK (OR(adj) 0.83; 95% CI 0.66-1.04; P = 0.10; P(interaction) = 0.58). Major bleeding rates including intracranial hemorrhage within the fibrin-specific cohort were 1.2 and 2.0% in the UFH and enoxaparin groups, respectively (P < 0.001) and 2.0% in UFH and 2.4% in enoxaparin patients in the SK cohort (P = 0.16). Interaction tests between antithrombin- and lytic-type were non-significant (P = 0.20). Death, nonfatal MI, or major bleeding was significantly reduced with enoxaparin in the fibrin-specific cohort (OR(adj) 0.82; 95% CI 0.74-0.91; P < 0.001) and favoured enoxaparin in the SK cohort (OR(adj) 0.89; 95% CI 0.72-1.10; P = 0.29; P(interaction) = 0.53). CONCLUSION: The benefits of an enoxaparin strategy over UFH were observed in both SK and fibrin-specific-treated STEMI patients. Therefore, an enoxaparin strategy is preferred over UFH to support fibrinolysis for STEMI regardless of lytic agent.     

A strategy of using enoxaparin as adjunctive antithrombin therapy reduces death and recurrent myocardial infarction in patients who achieve early ST-segment resolution after fibrinolytic therapy: the ExTRACT-TIMI 25 ECG study.

AIMS: To determine the relationship between a strategy of enoxaparin (ENOX), early ST-segment resolution (STRes), and clinical outcomes on patients with ST-segment elevation myocardial infarction (STEMI) after fibrinolysis. METHODS AND RESULTS: Baseline and 180 min ECGs were analysed in 3208 of the 20 479 patients in the ExTRACT-TIMI 25 trial, which randomifzed patients with STEMI to ENOX vs. unfractionated heparin (UFH) as adjunctive therapy. STRes was defined as complete (70%), partial (30-70%), or none (<30%). There was no evidence for a difference in STRes between the groups assigned to the ENOX or UFH (median 69.4 vs. 67.2%; P = 0.13). Among patients with complete STRes (n = 1100), ENOX significantly reduced death or non-fatal recurrent MI at 30 days when compared with UFH (4.4 vs. 9.9%; OR(adj) 0.39; P < 0.001), whereas there was no difference in patients with only partial or no STRes [14.2 vs. 12.5%; OR(adj) 1.0; P = 0.98 (n = 368) and 16.2 vs. 15.9%; OR(adj) 1.0; P = 0.97 (n = 830), P for interaction = 0.008]. CONCLUSION: When compared with UFH, a strategy of ENOX significantly reduces death or non-fatal recurrent MI in patients who achieved complete STRes, but not in patients with less STRes. These data suggest that a strategy of ENOX improves outcomes by preventing re-occlusion in patients achieving initial successful reperfusion after fibrinolytic therapy rather than by facilitating initial reperfusion.     

Enoxaparin vs. unfractionated heparin with fibrinolysis for ST-elevation myocardial infarction in elderly and younger patients: results from ExTRACT-TIMI 25.

AIMS: To determine the effects of age on outcomes in patients with STEMI treated with a strategy of enoxaparin (ENOX) vs. unfractionated heparin (UFH). METHODS AND RESULTS: In the ExTRACT-TIMI 25 trial, 20,479 patients with STEMI were randomized in a double-blind fashion to UFH or ENOX. A novel reduced dose of ENOX was administered to patients >or=75 years, and a reduced dose in those with an estimated creatinine clearance of < 30 mL/min. Anti-Xa levels were measured in a subset of patients (n = 73). The exposure to anti-Xa over time was lower in the elderly (AUC(0-12 h) P < 0.0001; AUC(steady-state) P = 0.0046). The relative risk reduction (RR) with ENOX on the primary endpoint, i.e. death or non-fatal recurrent myocardial infarction, was greater in patients < 75 years (20%) than > 75 years (6%), but the absolute benefits were similar. When compared with UFH, ENOX was associated with an RR of 1.67 for major bleeding, but the magnitude of the excess risk tended to be lower (RR = 1.15) in patients >or= 75 years assigned to ENOX. CONCLUSION: A dose reduction of ENOX in the elderly appears to be helpful in ameliorating bleeding risk. A strategy of ENOX was superior to UFH in both young and elderly patients with STEMI treated with fibrinolysis.     

Safety and effectiveness of enoxaparin following fibrinolytic therapy: Results of the Acute Myocardial Infarction (AMI)-QUEBEC registry

BACKGROUND:

Previous randomized controlled trials and meta-analyses demonstrated the superior efficacy of enoxaparin (ENOX) over unfractionated heparin (UFH) in patients with ST segment elevation myocardial infarction (STEMI). The external validity of randomized controlled trials may be limited by selective inclusion of patients who are younger and healthier than the ‘real-life’ population.

OBJECTIVE:

To evaluate the safety and effectiveness of ENOX compared with UFH in unselected STEMI patients.

METHODS:

The safety and effectiveness of ENOX and UFH were compared in STEMI patients who received fibrinolytic therapy at 17 Quebec hospitals in 2003.

RESULTS:

A total of 498 STEMI patients received systemic anticoagulation, with ENOX and UFH administered in 114 and 384 patients, respectively. There were no differences in baseline characteristics between the two patient groups. The rates of in-hospital major adverse cardiac or cerebral events were 11.4% in the ENOX group compared with 14.0% in the UFH group (P=0.51). In-hospital death or nonfatal reinfarction occurred in 7.9% of patients who received ENOX compared with 9.9% of patients who received UFH (P=0.52). Major bleeding occurred in 4.4% of patients who received ENOX versus 6.0% in patients who received UFH (P=0.51).

INTERPRETATION:

There was no significant difference in the rates of in-hospital adverse events in the ENOX group compared with the UFH group, when used in the real-life context. Larger observational studies may further confirm the safety, effectiveness and optimal duration of the administration of ENOX in unselected STEMI patients treated with fibrinolysis.     

ExTRACT-TIMI 25 in perspective: key lessons regarding enoxaparin as an adjunct to fibrinolytic therapy

Unfractionated heparin (UFH) for 48 h has been the traditional standard anticoagulant with fibrinolytics. The Enoxaparin and Thrombolysis Reperfusion for Acute Myocardial Infarction (ExTRACT)-Thrombolysis in Myocardial Infarction (TIMI) 25 trial prospectively studied the usefulness of enoxaparin and found that in patients treated with fibrinolysis, enoxaparin administered throughout the index hospitalization was superior to the standard 48-h UFH infusion. However, enoxaparin increased major bleeding. The data from this large trial were further analyzed across various subgroups and these results support the use of enoxaparin in a broad range of patients. The ExTRACT-TIMI 25 trial employed a novel dosing regimen for enoxaparin adjusted for age and renal function, which was designed to minimize bleeding risk while maintaining the beneficial effects of enoxaparin. Based on the evidence from this trial, the 2007 ST-segment elevation myocardial infarction guidelines now preferentially recommend enoxaparin to be administered throughout the index hospitalization as per the dosing regimen used in ExTRACT-TIMI 25 in most patients treated with fibrinolytic therapy.     

The safety and efficacy of subcutaneous enoxaparin versus intravenous unfractionated heparin and tirofiban versus placebo in the treatment of acute ST-segment elevation myocardial infarction patients ineligible for reperfusion (TETAMI): a randomized trial

OBJECTIVES: The aims of the Safety and Efficacy of Subcutaneous Enoxaparin Versus Intravenous Unfractionated Heparin and Tirofiban Versus Placebo in the Treatment of Acute ST-Segment Elevation Myocardial Infarction Patients Ineligible for Reperfusion (TETAMI) study were to demonstrate that enoxaparin was superior to unfractionated heparin (UFH) and that tirofiban was better than placebo in patients with acute ST-segment elevation myocardial infarction (STEMI) who do not receive timely reperfusion. BACKGROUND: An optimal treatment strategy has not been identified for the many STEMI patients ineligible for acute reperfusion. METHODS: A total of 1224 patients were enrolled in 91 centers in 14 countries between July 1999 and July 2002. Patients with STEMI ineligible for reperfusion were randomized to enoxaparin, enoxaparin plus tirofiban, UFH, or UFH plus tirofiban. All patients received oral aspirin. The primary efficacy end point was the 30-day combined incidence of death, reinfarction, or recurrent angina; the primary analysis was the comparison of the pooled enoxaparin and UFH groups. REULTS: The incidence of the primary efficacy end point was 15.7% enoxaparin versus 17.3% for UFH (odds ratio 0.89 [95% confidence interval CI = 0.66 to 1.21]) and 16.6% for tirofiban versus 16.4% for placebo (odds ratio 1.02 [95% CI 0.75 to 1.38]). The Thrombolysis In Myocardial Infarction (TIMI) major hemorrhage rate was 1.5% for enoxaparin versus 1.3% for UFH (odds ratio 1.16 [95% CI 0.44 to 3.02]) and 1.8% versus 1% for tirofiban versus placebo (odds ratio 1.82 [95% CI 0.67 to 4.95]). CONCLUSIONS: This study did not show that enoxaparin significantly reduced the 30-day incidence of death, reinfarction, and recurrent angina compared with UFH in non-reperfused STEMI patients. However, enoxaparin appears to have a similar safety and efficacy profile to UFH and may be an alternative treatment. Additional therapy with tirofiban did not appear beneficial.     

Outcome of urgent and elective percutaneous coronary interventions after pharmacologic reperfusion with tenecteplase combined with unfractionated heparin, enoxaparin, or abciximab

OBJECTIVES: The aim of this study was to evaluate percutaneous coronary intervention (PCI) in the Assessment of the Safety and Efficacy of New Thrombolytic Regimens (ASSENT-3) trial. BACKGROUND: In the ASSENT-3 trial, co-therapy with abciximab (ABC) or enoxaparin (ENOX) reduced ischemic complications after ST-elevation acute myocardial infarction treated with tenecteplase when compared with unfractionated heparin (UFH). The effect of these new co-therapies on the results of PCI is unknown. METHODS: Clinical outcomes in patients who received co-therapy with ABC, ENOX, or UFH and subsequently underwent an elective (n = 1,064) or urgent (n = 716) PCI in the ASSENT-3 trial were compared. RESULTS: No significant differences in clinical end points were observed in patients who underwent an elective PCI. A non-significant trend toward fewer in-hospital myocardial re-infarctions was seen with ABC and ENOX when compared with UFH (0.5% vs. 0.6% vs. 1.5%, respectively). The incidence of bleeding complications was similar in the three treatment arms. Significantly fewer ABC- and ENOX-treated patients needed urgent PCI compared with UFH (9.1% vs. 11.9% vs. 14.3%; p < 0.0001), but outcomes in these patients were in general less favorable (30-day mortality: 8.2% vs. 5.4% vs. 4.5%; 1-year mortality: 11.0% vs. 8.5% vs. 5.6%; in-hospital re-infarction: 3.9% vs. 2.5% vs. 2.7%; major bleeding complications: 8.8% vs. 7.0% vs. 3.4%). In pairwise comparisons with UFH, the higher one-year mortality and major bleeding rates after ABC were statistically significant (p = 0.045 and p = 0.012, respectively). CONCLUSIONS: Clinical outcomes after elective PCI were similar with the three antithrombotic co-therapies studied in ASSENT-3. Although fewer patients needed urgent PCI with ABC and ENOX, clinical outcomes were less favorable in this selected population, especially with ABC.     

Ticagrelor Versus Clopidogrel in Patients With STEMI Treated With Fibrinolysis: TREAT Trial

BackgroundThe efficacy of ticagrelor in the long-term post–ST-segment elevation myocardial infarction (STEMI) treated with fibrinolytic therapy remains uncertain.ObjectivesThe purpose of this study was to evaluate the efficacy of ticagrelor when compared with clopidogrel in STEMI patients treated with fibrinolytic therapy.MethodsThis international, multicenter, randomized, open-label with blinded endpoint adjudication trial enrolled 3,799 patients (age <75 years) with STEMI receiving fibrinolytic therapy. Patients were randomized to ticagrelor (180-mg loading dose, 90 mg twice daily thereafter) or clopidogrel (300- to 600-mg loading dose, 75 mg daily thereafter). The key outcomes were cardiovascular mortality, myocardial infarction, or stroke, and the same composite outcome with the addition of severe recurrent ischemia, transient ischemic attack, or other arterial thrombotic events at 12 months.ResultsThe combined outcome of cardiovascular mortality, myocardial infarction, or stroke occurred in 129 of 1,913 patients (6.7%) receiving ticagrelor and in 137 of 1,886 patients (7.3%) receiving clopidogrel (hazard ratio: 0.93; 95% confidence interval: 0.73 to 1.18; p = 0.53). The composite of cardiovascular mortality, myocardial infarction, stroke, severe recurrent ischemia, transient ischemic attack, or other arterial thrombotic events occurred in 153 of 1,913 patients (8.0%) treated with ticagrelor and in 171 of 1,886 patients (9.1%) receiving clopidogrel (hazard ratio: 0.88; 95% confidence interval: 0.71 to 1.09; p = 0.25). The rates of major, fatal, and intracranial bleeding were similar between the ticagrelor and clopidogrel groups.ConclusionAmong patients age <75 years with STEMI, administration of ticagrelor after fibrinolytic therapy did not significantly reduce the frequency of cardiovascular events when compared with clopidogrel. (Ticagrelor in Patients With ST Elevation Myocardial Infarction Treated With Pharmacological Thrombolysis [TREAT]; NCT02298088)     

Efficacy and safety of triple antiplatelet therapy with and without concomitant anticoagulation during elective percutaneous coronary intervention (the REMOVE trial)

Adjunctive glycoprotein IIb/IIIa inhibition decreases ischemic events after percutaneous coronary intervention (PCI) but is associated with increased bleeding. We hypothesized that maximal antiplatelet therapy with aspirin, a thienopyridine, and a glycoprotein IIb/IIIa inhibitor without unfractionated heparin (UFH) would result in fewer bleeding complications and maintain efficacy in elective PCI. A total of 159 patients undergoing elective PCI were randomized to intraprocedural eptifibatide alone or eptifibatide plus UFH. Patients received aspirin 325 mg and clopidogrel 300 mg before the procedure. The primary end point was the Landefeld bleeding index. Secondary end points included the composite clinical outcome of in-hospital death, myocardial infarction, urgent target vessel revascularization, and Thrombolysis In Myocardial Infarction major bleeding, and a composite bleeding outcome of major, minor, and nuisance bleeding. The Landefeld bleeding index was significantly lower in the eptifibatide-only group compared with the eptifibatide-plus-UFH group (3.0 vs 3.9, p = 0.03). There was no significant difference in the composite clinical end point between groups (eptifibatide only 17% vs eptifibatide plus UFH 15%, p = 0.7). There was a trend toward a decrease in the composite bleeding end point in the eptifibatide-only compared with the eptifibatide-plus-UFH group (43% vs 56%, p = 0.10). In conclusion, during elective PCI, a strategy of aggressive antiplatelet therapy using aspirin, clopidogrel, and eptifibatide without anticoagulant therapy appears to decrease bleeding complications.     

Angiographic and clinical outcomes associated with direct versus conventional stenting among patients treated with fibrinolytic therapy for ST-elevation acute myocardial infarction

The present study reports outcomes of direct stenting versus conventional stenting, which was performed during adjunctive/rescue percutaneous coronary intervention (n = 556) in the Integrilin and Tenecteplase in Acute Myocardial Infarction trial, the Enoxaparin as Adjunctive Antithrombin Therapy for ST-Elevation Myocardial Infarction-Thrombolysis in Myocardial Infarction 23 trial, and the Fibrinolytic and Aggrastat ST-Elevation Resolution trial of fibrinolytic therapy in ST-elevation myocardial infarction. Direct stenting was associated with a lower rate of death, myocardial infarction, or congestive heart failure during hospitalization and at 30 days and was independently associated with improved in-hospital outcomes (odds ratio 0.44, 95% confidence interval 0.23 to 0.85, p = 0.014).     

Comparison of bleeding and in-hospital mortality in Asian-Americans versus Caucasian-Americans with ST-elevation myocardial infarction receiving reperfusion therapy

Concern has been raised that Asian-Americans may have a higher bleeding risk than Caucasian-Americans when treated with fibrinolytic and antithrombotic agents. To date there is limited evidence to support or refute this hypothesis or evaluate bleeding risk and its related outcomes in Caucasian-Americans versus Asian-Americans with ST-segment elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary interventions (PPCI). We evaluated Asian-Americans and Caucasian-Americans with STEMI receiving reperfusion therapy in the National Registry of Myocardial Infarction (NRMI) 4 and 5 (n = 90,317). We studied risk-adjusted major bleeding and in-hospital mortality. Major bleeding rates after fibrinolysis were similar in Asian-Americans (n = 705) and Caucasian-Americans (n = 42,243, 11.1% vs 10.3%, adjusted odds ratio [OR] 0.97, 95% confidence interval [CI] 0.69 to 1.36, p = 0.5002). Although the observed major bleeding rate was higher in Asian-Americans (n = 1,037) compared to Caucasian-Americans (n = 46,332) treated with PPCI (10.3% vs 7.8%, p = 0.0036), these rates differed only marginally after adjusting for baseline clinical variables (OR 1.24, 95% CI 0.97 to 1.59). Overall adjusted mortality was similar in Asian-Americans and Caucasian-Americans when treated with fibrinolysis (OR 0.96, 95% CI 0.56 to 1.65) or with PPCI (OR 1.35, 95% CI 0.85 to 2.13). Major bleeding after PPCI or fibrinolysis was associated with similar increased risks for mortality in these ethic groups. In conclusion, despite suggestions to the contrary, Asian-Americans with STEMI treated with fibrinolysis or PPCI had similar bleeding and bleeding-related mortality risks compared to Caucasian-Americans. Given the genotypic and phenotypic differences between the 2 cohorts, similar studies in the rapidly growing Asian-American population are needed to confirm our findings and to understand the safety and effectiveness of newer potent antiplatelet and antithrombotic agents in patients with coronary syndromes.     

Association of duration of symptoms at presentation with angiographic and clinical outcomes after fibrinolytic therapy in patients with ST-segment elevation myocardial infarction.

OBJECTIVES: We sought to determine if an underlying mechanism of the association between prolonged symptom-to-treatment times and adverse outcomes may be an association of symptom-to-treatment times with impaired Thrombolysis In Myocardial Infarction myocardial perfusion grades (TMPGs). BACKGROUND: Prolonged symptom duration among ST-segment elevation myocardial infarction (STEMI) patients undergoing fibrinolytic therapy is associated with adverse outcomes. METHODS: Angiography was performed 60 min after fibrinolytic administration in 3,845 Thrombolysis In Myocardial Infarction (TIMI) trial patients. RESULTS: The median time from symptom onset to treatment was longer among patients with impaired myocardial perfusion (3.0 h for TMPG 0/1 vs. 2.7 h for TMPG 2/3; p = 0.001). In a multivariate model, impaired tissue perfusion (TMPG 0/1) remained associated with increased time to treatment (odds ratio 1.14 per hour of delay; p = 0.007) even after adjusting for Thrombolysis In Myocardial Infarction flow grade (TFG) 3, left anterior descending infarct location, and baseline clinical characteristics. Impaired myocardial perfusion after rescue/adjunctive percutaneous coronary intervention (PCI) was associated with longer median times to treatment (3.0 h for TMPG 2/3 vs. 2.7 h for TMPG 0/1; p = 0.017), as was abnormal epicardial flow after rescue/adjunctive PCI (3.3 h for TFG 0/1/2 vs. 2.8 h for TFG 3; p = 0.005). Thirty-day mortality was associated with longer time from onset of symptoms to treatment (6.6% mortality for time to treatment >4 h vs. 3.3%; p < 0.001), even among patients undergoing rescue PCI. CONCLUSIONS: A prolonged symptom to treatment time among STEMI patients is associated with impaired myocardial perfusion independent of epicardial flow both immediately after fibrinolytic administration and after rescue/adjunctive PCI. These data provide a pathophysiologic link between prolonged symptoms due to vessel occlusion, impaired myocardial perfusion, and poor clinical outcomes.     

Subcutaneous enoxaparin following thrombolysis and intravenous unfractionated heparin in ST-elevation acute myocardial infarction: safety and efficacy of low vs full dose

AIM: In ST-segment elevation myocardial infarction (STEMI) treated with fibrin-specific thrombolytic agents, early intravenous unfractionated heparin (UFH) is warranted. Low molecular weight heparin Enoxaparin currently represents an alternative to UFH, to be used until hospital discharge. Since optimal dosing of subcutaneous Enoxaparin is not standardized, we conducted an observational study to compare safety and efficacy of low (4,000 U once daily) vs full dose (100 U/kg twice daily) regimens. METHODS: All STEMI patients successfully treated with tenecteplase and intravenous UFH and referred to the Catheterization Laboratory between June 2002-November 2003 for predischarge coronary angiography, were evaluated. The primary end-point was the composite of hemorrhages and residual angina/reinfarction during Enoxaparin administration, whereas secondary end-points were occurrence of venous thromboembolism (VTE) during Enoxaparin administration, and infarct-related artery (IRA) patency rate at predischarge coronary angiography. RESULTS: Out of 123 patients, 57 (M/F 45/12, mean age 65.8+/-8.1 years) received low dose, and 66 (men/women 45/21, mean age 62.6+/-11.8 years) full dose subcutaneous Enoxaparin. The incidence of the composite primary end-point was comparable in both groups (19% vs 26%; P=NS). Also, null was the occurrence of VTE, whereas the IRA patency rate did not significantly differ in the 2 groups (84% vs 86% TIMI 3 and 11% vs 9% TIMI 2 flow grades; P=NS). CONCLUSIONS: In patients with STEMI undergoing successful recanalization with tenecteplase and intravenous UFH, low dose subcutaneous Enoxaparin appears preferable to full dose, in the light of comparable safety and clinical efficacy and superior easiness of use.     

A novel point-of-care enoxaparin monitor for use during percutaneous coronary intervention. Results of the Evaluating Enoxaparin Clotting Times (ELECT) Study

OBJECTIVES: The aim of this study was to discern a target range of anticoagulation for enoxaparin during percutaneous coronary intervention (PCI) as measured by the Rapidpoint ENOX (Pharmanetics Inc., Morrisville, North Carolina), a new point-of-care test. BACKGROUND: In the U.S., enoxaparin has been used in only a small proportion of PCI procedures, partly because a rapid enoxaparin-specific assay was unavailable. METHODS: We analyzed data from 445 enrolled patients receiving subcutaneous or intravenous enoxaparin in a prospective, multicenter study. Serial anticoagulation measurements and clinical outcomes were recorded. RESULTS: The in-hospital composite occurrence of death, myocardial infarction, and urgent target vessel revascularization was 5.4%, and Thrombolysis In Myocardial Infarction (TIMI) major bleeding, minor bleeding, and any reported bleeding occurred in 0.2%, 1.3%, and 7.9% of patients, respectively. No significant association between procedural ENOX times and ischemic events was observed (p = 0.222), although the event rate was 4.0% among those with ENOX times between 250 to 450 s versus 7.2% for those outside this range (p = 0.134). Increasing ENOX time at sheath removal was correlated with any bleeding (p = 0.010) with a 1% increase for every approximately 30-s rise. CONCLUSIONS: Ischemic events were infrequent, and the rate appeared lowest in the mid-range of ENOX times. Bleeding events increased with increasing ENOX times. These observations, combined with a suggested procedural anti-Xa level of 0.8 to 1.8 IU/ml, translate into a recommended ENOX time range of 250 to 450 s for PCI and <200 to 250 s for sheath removal.     

Comparative early and late outcomes after primary percutaneous coronary intervention in ST-segment elevation and non-ST-segment elevation acute myocardial infarction (from the CADILLAC trial)

We determined the outcomes of patients with acute ST-segment elevation (STE) myocardial infarction (STEMI) and non-STEMI (NSTEMI) after primary percutaneous coronary intervention (PCI). The prognosis after primary PCI in STEMI has been extensively studied and defined. Outcomes of patients who undergo primary PCI for NSTEMI are less well established. In total, 2,082 patients with ongoing chest pain for > 30 minutes consistent with acute MI were randomized to balloon angioplasty versus stenting, each with/without abciximab. Of 1,964 patients, STEMI was present in 1,725 (87.8%) and NSTEMI in 239 (12.2%). Compared with STEMI, those with NSTEMI were more likely to have delayed time-to-hospital arrival (2.4 vs 1.8 hours, p = 0.0002) and increased door-to-balloon time (3.2 vs 1.9 hours, p < 0.0001). Patients with NSTEMI were more likely to have Thrombolysis In Myocardial Infarction grade 3 flow at baseline (37.3% vs 19.4%, p < 0.0001) and higher ejection fraction (58.7% vs 55.8%, p = 0.001), but similar rates of postprocedural Thrombolysis In Myocardial Infarction grade 3 flow. At 1 year, patients with NTEMI had similar mortality (3.4% vs 4.4%, p = 0.40) but higher rates of major adverse cardiac events (24.0% vs 16.6%, p = 0.007) that was driven by more frequent ischemic target vessel revascularization (21.8% vs 11.9%, p <0.0001). In conclusion, patients with acute MI without STE who are treated with primary PCI have marked delays to treatment, similar late mortality, and increased rates of ischemic target vessel revascularization compared with patients with STEMI, despite more favorable angiographic features at presentation and similar reperfusion success. The adverse prognosis of patients with NSTEMI should be recognized and efforts made to decrease reperfusion times.     

Prehospital fibrinolysis with dual antiplatelet therapy in ST-elevation acute myocardial infarction: a substudy of the randomized double blind CLARITY-TIMI 28 trial

Background Fibrinolytic therapy for acute ST-elevation myocardial infarction (STEMI) is frequently limited by delays in administration and by incomplete reperfusion or reocclusion of the infarct-related artery. Intensified prehospital management of STEMI may shorten time to treatment and improve outcomes. Methods We carried out a prospective substudy in 11 ambulance systems in 216 of the 3,491 patients with STEMI who were enrolled in the CLARITY-TIMI 28 trial. They were randomized in the ambulance to clopidogrel (n = 109) or placebo (n = 107) along with fibrinolysis, aspirin, and heparin. The primary endpoint was the composite of an occluded infarct-related artery (TIMI flow grade 0 or 1), or death or recurrent myocardial infarction before angiography. Results All patients received a fibrin-specific lytic and the baseline characteristics in both groups were comparable. The incidence of the primary endpoint was 16.5% in the clopidogrel-treated and 27.1% in the placebo patients (adj OR 0.62, 95% CI 0.31–1.21, p = 0.16), an effect that was consistent with the effects seen in the in-hospital patients in the main CLARITY-TIMI 28 trial. Prehospital clopidogrel therapy reduced the incidence of an occluded infarct-related artery on the predischarge angiogram (11.8% vs. 22.3%, adj OR 0.52, 95% CI 0.24–1.13, p = 0.10). The 30-day incidence of cardiovascular death, recurrent MI or recurrent myocardial ischemia requiring urgent revascularization was 12.8% vs. 14.0% (adj OR 1.07, 95% CI 0.48–2.39, p = 0.87). Early TIMI major bleeding occurred in no clopidogrel patients compared with two placebo patients (1.9%). Conclusions Addition of clopidogrel to medical reperfusion of STEMI with fibrinolysis, heparin, and aspirin before reaching the hospital is feasible in medically equipped ambulances without an apparent increase in bleeding. Furthermore, prehospital clopidogrel tended to show better early coronary patency compared to placebo, a result consistent with that observed in patients randomized in-hospital in the CLARITY-TIMI 28 trial.     

B-type natriuretic peptide at presentation and prognosis in patients with ST-segment elevation myocardial infarction: an ENTIRE-TIMI-23 substudy

OBJECTIVES: We sought to evaluate B-type natriuretic peptide (BNP), alone and in comparison to cardiac troponin I (cTnI) and high-sensitivity C-reactive protein (hs-CRP), for risk assessment at initial presentation with ST-segment elevation myocardial infarction (STEMI). BACKGROUND: Elevated levels of BNP drawn two to four days after acute myocardial infarction are associated with higher mortality. Sparse data are available on its use at first presentation with STEMI. METHODS: We obtained samples from 438 patients presenting within 6 h of STEMI enrolled in the Enoxaparin Tenecteplase-Tissue-Type Plasminogen Activator With or Without Glycoprotein IIb/IIIa Inhibitor as Reperfusion Strategy in ST-Segment Elevation Myocardial Infarction (ENTIRE)-Thrombolysis In Myocardial Infarction (TIMI)-23 trial. Outcomes were assessed through 30 days. RESULTS: Median BNP was higher in patients who died (89 pg/ml, 25th to 75th percentile: 40 to 192), compared with survivors (15 pg/ml, 25th to 75th percentile: 8.8 to 32, p < 0.0001). Patients with BNP >80 pg/ml were at significantly higher risk of death (17.4% vs. 1.8%, p < 0.0001). Cardiac troponin established a gradient of mortality between the highest and lowest quartile (7.9% vs. 0%, p = 0.007). C-reactive protein was not associated with outcome. After adjustment for cTnI, hs-CRP, and major clinical predictors, including age, heart failure, anterior myocardial infarction location, heart rate, and blood pressure, a BNP level >80 pg/ml was associated with a seven-fold higher mortality risk (odds ratio 7.2, 95% confidence interval 2.1 to 24.5, p = 0.001). Patients with BNP >80 pg/ml were also more likely to have impaired coronary flow (p = 0.049) and incomplete resolution of ST-segment elevation (p = 0.05). CONCLUSIONS: Increased concentrations of BNP at initial presentation of patients with STEMI are associated with impaired reperfusion after fibrinolysis and higher short-term risk of mortality. These data support the value of combining markers of hemodynamic stress with traditional approaches to risk assessment in acute myocardial infarction.     

Rheolytic thrombectomy with percutaneous coronary intervention for infarct size reduction in acute myocardial infarction: 30-day results from a multicenter randomized study.

OBJECTIVES: The goal of this work was to determine whether rheolytic thrombectomy (RT) as an adjunct to primary percutaneous coronary intervention (PCI) reduces infarction size and improves myocardial perfusion during treatment of ST-segment elevation myocardial infarction (STEMI). BACKGROUND: Primary PCI for STEMI achieves brisk epicardial flow in most patients, but myocardial perfusion often remains suboptimal. Distal embolization of thrombus during treatment may be a contributing factor. METHODS: This prospective, multicenter trial enrolled 480 patients presenting within 12 h of symptom onset and randomized to treatment with RT as an adjunct to PCI (n = 240) or to PCI alone (n = 240). Visible thrombus was not required. The primary end point was infarct size measured by sestamibi imaging at 14 to 28 days. Secondary end points included final Thrombolysis In Myocardial Infarction (TIMI) flow grade, tissue myocardial perfusion (TMP) blush, ST-segment resolution, and major adverse cardiac events (MACE), defined as the occurrence of death, new Q-wave myocardial infarction, emergent coronary artery bypass grafting, target lesion revascularization, stroke, or stent thrombosis at 30 days. RESULTS: Final infarct size was higher in the adjunct RT group compared with PCI alone (9.8 +/- 10.9% vs. 12.5 +/- 12.13%; p = 0.03). Final TIMI flow grade 3 was lower in the adjunct RT group (91.8% vs. 97.0% in the PCI alone group; p < 0.02), although fewer patients had baseline TIMI flow grade 3 in the adjunct RT group (44% vs. 63% in the PCI alone group; p < 0.05). There were no significant differences in TMP blush scores or ST-segment resolution. Thirty-day MACE was higher in the adjunct RT group (6.7% vs. 1.7% in the PCI alone group; p = 0.01), a difference primarily driven by very low mortality rate in patients treated with PCI alone (0.8% vs. 4.6% in patients treated with adjunct RT; p = 0.02). CONCLUSIONS: Despite effective thrombus removal, RT with primary PCI did not reduce infarct size or improve TIMI flow grade, TMP blush, ST-segment resolution, or 30-day MACE.