Edoxaban for treatment of venous thromboembolism in patient groups with different types of cancer: Results from the Hokusai VTE Cancer study.

BACKGROUND: The safety and efficacy of edoxaban and dalteparin is unclear for several cancer groups. METHODS: We evaluated the occurrence of the primary outcome in large cancer groups. The primary outcome was the composite of recurrent VTE or major bleeding over 12 months. RESULTS: In patients with gastrointestinal cancer, the primary outcome occurred in 19.4% patients given edoxaban and in 15.0% given dalteparin (risk difference [RD], 4.4%; 95%-CI, -4.1% to 12.8%). The corresponding rates for edoxaban and dalteparin were 10.4% and 10.7% for lung cancer (RD, -0.3%; 95%-CI, -10.0% to 9.5%), 13.6% and 12.5% for urogenital cancer (RD, 1.1; 95%-CI, -10.1-12.4), 3.1% and 11.7% for breast cancer (RD, -8.6; 95%-CI, -19.3-2.2), 8.9% and 10.9% for hematological malignancies (RD, -2.0; 95%-CI, -13.1-9.1), and 10.4% and 17.4% for gynecological cancer (RD, -7.0; 95%-CI, -19.8-5.7). In the subgroup of gastrointestinal cancer, edoxaban was associated with a 3.5% lower absolute risk of recurrent VTE and a 7.9% higher risk of major bleeding. CONCLUSION: Edoxaban has a similar risk-benefit ratio to dalteparin in most cancer groups. In those with gastrointestinal cancer, the lower risk of recurrent VTE and the advantages of oral therapy need to be balanced against the increased risk of major bleeding.

Rivaroxaban reversal with prothrombin complex concentrate or tranexamic acid in healthy volunteers.

Essentials Specific reversal agents for managing severe factor Xa inhibitor-associated bleeding are lacking. We assessed 4-factor-prothrombin complex concentrate (4F-PCC) and tranexamic acid (TXA). 4F-PCC, but not TXA, reduced the prothrombin time and increased endogenous thrombin potential. These agents may be viable options for reversal of therapeutic doses of rivaroxaban. SUMMARY: Background Oral activated factor X inhibitors such as rivaroxaban are widely used, but specific reversal agents are lacking. Although four-factor prothrombin complex concentrate (4F-PCC) and tranexamic acid (TXA) are sometimes used to manage serious bleeding, their efficacy is unknown. Prior studies in healthy subjects taking rivaroxaban revealed that 4F-PCC partially reverses the prolonged prothrombin time (PT), and fully restores the endogenous thrombin potential (ETP). The effect of TXA has not been evaluated. Methods In this double-blind, parallel-group study, 147 healthy volunteers given rivaroxaban 20 mg twice daily for 3 days were randomized after their morning dose on day 4 to receive intravenous 4F-PCC (50 IU kg-1 ), TXA (1.0 g), or saline. Standardized punch biopsies were performed at baseline and after 4F-PCC, TXA or saline administration. Reversal was assessed by measuring bleeding duration and bleeding volume at biopsy sites, and by determining the PT and ETP. Results As compared with saline, 4F-PCC partially reversed the PT and completely reversed the ETP, whereas TXA had no effect. Neither 4F-PCC nor TXA reduced bleeding duration or volume. All treatments were well tolerated, with no recorded adverse events. Conclusions Although 4F-PCC reduced the PT and increased the ETP in volunteers given supratherapeutic doses of rivaroxaban, neither 4F-PCC nor TXA influenced punch biopsy bleeding.

Comparison of the ecarin chromogenic assay and diluted thrombin time for quantification of dabigatran concentrations.

Essentials Routine monitoring is unnecessary but measuring dabigatran levels is helpful in certain situations. We compared ecarin chromogenic assay (STA-ECA-II) and dilute thrombin time (dTT) in patient samples. Both tests provided accurate measurements over a wide range of dabigatran concentrations. Adoption of STA-ECA-II and dTT into routine clinical practice will improve patient care. SUMMARY: Background Although routine coagulation monitoring is unnecessary, measuring plasma dabigatran concentrations can be useful for detecting drug accumulation in renal failure or overdose, assessing the contribution of dabigatran to serious bleeding, planning the timing of urgent surgery or intervention, or determining the suitability for thrombolytic therapy for acute ischemic stroke. Dabigatran concentrations can be quantified using chromogenic or clot-based tests, such as the ecarin chromogenic assay (ECA) and the diluted thrombin time (dTT), respectively. Objective The purpose of this study was to compare the results of these assays with dabigatran concentrations measured by the reference standard of mass spectrometry in samples from 50 dabigatran-treated patients collected at peak and trough after at least 4 months of drug intake. Methods Drug levels measured with either the STA Ecarin Chromogenic Assay-II (STA-ECA-II) or dTT were linearly correlated with those determined by mass spectrometry over a wide range of concentrations. Results and Conclusions For detection of levels below 50 ng mL-1 both tests have specificities of at least 96%, suggesting that they accurately detect even low levels of drug. Therefore, regardless of whether a chromogenic or clot-based platform is preferred, the STA-ECA-II and dTT are useful tests for measuring dabigatran concentrations. Unfortunately, neither test is licensed by the United States Food and Drug Administration. Although approved in other jurisdictions, the dTT and STA-ECA-II are not widely or rapidly available in most hospitals. Therefore, cooperation between regulators and hospitals is urgently needed to render these tests readily available to inform patient care.

Once versus twice daily aspirin after coronary bypass surgery: a randomized trial.

Essentials Coronary artery bypass graft (CABG) failure is associated with myocardial infarction and death. We tested whether more frequent dosing improves aspirin (ASA) response following CABG surgery. Twice-daily compared with once-daily dosing reduces ASA hyporesponsiveness after CABG surgery. The efficacy of twice-daily ASA needs to be tested in a trial powered for clinical outcomes. SUMMARY: Background Acetyl-salicylic acid (ASA) hyporesponsiveness occurs transiently after coronary artery bypass graft (CABG) surgery and may compromise the effectiveness of ASA in reducing thrombotic graft failure. A reduced response to ASA 81 mg once-daily after CABG surgery is overcome by four times daily ASA dosing. Objectives To determine whether ASA 325 mg once-daily or 162 mg twice-daily overcomes a reduced response to ASA 81 mg once-daily after CABG surgery. Methods Adults undergoing CABG surgery were randomized to ASA 81 mg once-daily, 325 mg once-daily or 162 mg twice-daily. The primary outcome was median serum thromboxane B2 (TXB2 ) level on postoperative day 4. We pooled the results with those of our earlier study to obtain better estimates of the effect of ASA 325 mg once-daily or in divided doses over 24 h. Results We randomized 68 patients undergoing CABG surgery. On postoperative day 4, patients randomized to receive ASA 81 mg once-daily had a median day 4 TXB2 level of 4.2 ng mL-1 (Q1, Q3: 1.5, 7.5 ng mL-1 ), which was higher than in those randomized to ASA 162 mg twice-daily (1.1 ng mL-1 ; Q1, Q3: 0.7, 2.7 ng mL-1 ) and similar to those randomized to ASA 325 mg once-daily (1.9 ng mL-1 ; Q1, Q3: 0.9, 4.7 ng mL-1 ). Pooled data showed that the median TXB2 level on day 4 in groups receiving ASA 162 mg twice-daily or 81 mg four times daily was 1.1 ng mL-1 compared with 2.2 ng mL-1 in those receiving ASA 325 mg once-daily. Conclusions Multiple daily dosing of ASA is more effective than ASA 81 mg once-daily or 325 mg once-daily at suppressing serum TXB2 formation after CABG surgery. A twice-daily treatment regimen needs to be tested in a clinical outcome study.

Oral apixaban for the treatment of venous thromboembolism in cancer patients: results from the AMPLIFY trial.

BACKGROUND: The AMPLIFY trial compared apixaban with enoxaparin followed by warfarin for the treatment of acute venous thromboembolism (VTE). OBJECTIVE: To perform a subgroup analysis to compare the efficacy and safety of apixaban and enoxaparin followed by warfarin for the treatment of VTE in patients with cancer enrolled in AMPLIFY. PATIENTS/METHODS: Patients with symptomatic VTE were randomized to a 6-month course of apixaban or enoxaparin followed by warfarin. The primary efficacy outcome and principal safety outcome were recurrent VTE or VTE-related death and major bleeding, respectively. RESULTS: Of the 5395 patients randomized, 169 (3.1%) had active cancer at baseline, and 365 (6.8%) had a history of cancer without active cancer at baseline. Among patients with active cancer, recurrent VTE occurred in 3.7% and 6.4% of evaluable patients in the apixaban and enoxaparin/warfarin groups, respectively (relative risk [RR] 0.56, 95% confidence interval [CI] 0.13-2.37); major bleeding occurred in 2.3% and 5.0% of evaluable patients, respectively (RR 0.45, 95% CI 0.08-2.46). Among patients with a history of cancer, recurrent VTE occurred in 1.1% and 6.3% of evaluable patients in the apixaban and enoxaparin/warfarin groups, respectively (RR 0.17, 95% CI 0.04-0.78); major bleeding occurred in 0.5% and 2.8% of treated patients, respectively (RR 0.20, 95% CI 0.02-1.65). CONCLUSIONS: The results of this subgroup analysis suggest that apixaban is a convenient option for cancer patients with VTE. However, additional studies are needed to confirm this concept and to compare apixaban with low molecular weight heparin in these patients.

Global public awareness of venous thromboembolism.

BACKGROUND: Data on public awareness about thrombosis in general and venous thromboembolism (VTE) in particular are limited. We aimed to measure the global awareness of thrombosis to address this gap. METHODS: With Ipsos-Reid, from 22 July to 5 August 2014, we surveyed 800 respondents in their native language from each of Argentina, Australia, Canada, Germany, Japan, Thailand, the Netherlands, the United Kingdom and the United States to measure general awareness about thrombosis, including deep vein thrombosis (DVT) and pulmonary embolism (PE). In each country, respondents were distributed among three age groups: 18-39 years, 40-64 years, and over 65 years of age. Proportions and 95% confidence intervals (CIs) were calculated. RESULTS: Overall, the proportion of respondents that were aware of thrombosis, DVT and PE (68%, 44% and 54%, respectively) was lower than the proportion that was aware of other thrombotic disorders, such as heart attack and stroke (88% and 85%, respectively), and health conditions such as hypertension, breast cancer, prostate cancer and AIDS (90%, 85%, 82% and 87%, respectively). Although there was variation across countries, lower awareness was associated with younger age and being male. Only 45% (95% CI, 43.9-46.5) of respondents were aware that blood clots were preventable, and awareness of cancer, hospitalization and surgery as risk factors was low (16%, 25%, and 36%, respectively). CONCLUSIONS: On a global level, public awareness about thrombosis overall, and VTE in particular, is low. Campaigns to increase public awareness about VTE are needed to reduce the burden from this largely preventable thrombotic disorder.

Multiple daily doses of acetyl-salicylic acid (ASA) overcome reduced platelet response to once-daily ASA after coronary artery bypass graft surgery: a pilot randomized controlled trial.

BACKGROUND: The efficacy of ASA for prevention of graft failure following CABG surgery may be limited by incomplete platelet inhibition due to increased post-operative platelet turnover. OBJECTIVES: To determine whether acetyl-salicylic acid (ASA) 325 mg once-daily or 81 mg four-times daily overcomes the impaired response to ASA 81 mg once-daily in post-operative coronary artery bypass graft (CABG) patients. METHODS: We randomized 110 patients undergoing CABG surgery to either ASA 81 mg once-daily, 81 mg four times daily or 325 mg once-daily and compared their effects on serum thromboxane B2 (TXB2 ) suppression and arachidonate-induced platelet aggregation. RESULTS: One hundred patients were included in the final analysis. Platelet counts fell after surgery, reached a nadir on day 2, and then gradually increased. Although there was near complete suppression of TXB2 on the second or third post-operative day, TXB2 levels increased in parallel with the rise in platelet count on subsequent days. This increase was most marked in patients receiving ASA 81 mg once-daily and less evident in those receiving ASA four times daily. On post-operative day 4, (i) median TXB2 levels were lower with four times daily ASA than with either ASA 81 mg once-daily (1.1 ng/mL; Quartile(Q) Q1,Q3: 0.5, 2.4 and 13.3 ng/mL; Q1,Q3: 7.8, 30.8 ng/mL, respectively; P < 0.0001) or ASA 325 mg once-daily (3.4 ng/mL; Q1,Q3: 2.0, 8.2 ng/mL; P = 0.002), and (ii) ASA given four times daily was more effective than ASA 81 mg once-daily and 325 mg once-daily at suppressing platelet aggregation. CONCLUSIONS: Four times daily ASA is more effective than ASA 81 and 325 mg once-daily at suppressing serum TXB2 formation and platelet aggregation immediately following CABG surgery.

Comparison of the effect of coagulation and platelet function impairments on various mouse bleeding models.

Haemostatic impairments are studied in vivo using one of several murine bleeding models. However it is not known whether these models are equally appropriate for assessing coagulation or platelet function defects. It was our study objective to assess the performance of arterial, venous and combined arterial and venous murine bleeding models towards impaired coagulation or platelet function. Unfractionated heparin (UFH) or αIIbß3inhibitory antibody (Leo.H4) were administered to mice, and their effects on bleeding in saphenous vein, artery, and tail tip transection models were quantified and correlated with their effects on plasma clotting and ADP-induced platelet aggregation, respectively. All models exhibited similar sensitivity with UFH (EC50 dose = 0.19, 0.13 and 0.07 U/g, respectively) (95% CI = 0.14 - 0.27, 0.08 - 0.20, and 0.03 - 0.16 U/g, respectively). Maximal inhibition of ex vivo plasma clotting could be achieved with UFH doses as low as 0.03 U/g. In contrast, the saphenous vein bleeding model was less sensitive to αIIbß3 inhibition (EC50 = 6.9 µg/ml) than tail transection or saphenous artery bleeding models (EC50 = 0.12 and 0.37 µg/ml, respectively) (95% CI = 2.4 - 20, 0.05 - 0.33, and 0.06 - 2.2 µg/ml, respectively). The EC50 of Leo.H4 for ADP-induced platelet aggregation in vitro (8.0 µg/ml) was at least 20-fold higher than that of the tail and arterial, but not the venous bleeding model. In conclusion, venous, arterial and tail bleeding models are similarly affected by impaired coagulation, while platelet function defects have a greater influence in models incorporating arterial injury.

New anticoagulants.

The limitations of heparin and warfarin have prompted the development of new anticoagulant drugs for prevention and treatment of venous and arterial thromboembolism. Novel parenteral agents include synthetic analogs of the pentasaccharide sequence of heparin that mediates its interaction with antithrombin. Fondaparinux, the first synthetic pentasaccharide, is licensed for prevention of venous thromboembolism (VTE) after major orthopedic surgery and for initial treatment of patients with VTE. Idraparinux, a long-acting pentasaccharide that is administered subcutaneously once-weekly, is being compared with warfarin for treatment of VTE and for prevention of cardioembolic events in patients with atrial fibrillation. New oral anticoagulants include direct inhibitors of thrombin, factor Xa and factor IXa. Designed to provide more streamlined anticoagulation than warfarin, these agents can be given without routine coagulation monitoring. Ximelagatran, the first oral direct thrombin inhibitor, is as effective and safe as warfarin for prevention of cardioembolic events in patients with atrial fibrillation. However, ximelagatran produces a three-fold elevation in alanine transaminase levels in 7.9% of patients treated for more than a month, the long-term significance of which is uncertain. Whether other direct thrombin inhibitors or inhibitors of factors Xa or IXa also have this problem is under investigation. After a brief review of coagulation pathways, this paper focuses on new anticoagulants in advanced stages of clinical testing.

Comparison of 1 month with 3 months of anticoagulation for a first episode of venous thromboembolism associated with a transient risk factor.

BACKGROUND: The risk of recurrence is lower after treatment of an episode of venous thromboembolism associated with a transient risk factor, such as recent surgery, than after an episode associated with a permanent, or no, risk factor. Retrospective analyses suggest that 1 month of anticoagulation is adequate for patients whose venous thromboembolic event was provoked by a transient risk factor. METHODS: In this double-blind study, patients who had completed 1 month of anticoagulant therapy for a first episode of venous thromboembolism provoked by a transient risk factor were randomly assigned to continue warfarin or to placebo for an additional 2 months. Our goal was to determine if the duration of treatment could be reduced without increasing the rate of recurrent venous thromboembolism during 11 months of follow-up. RESULTS: Of 84 patients assigned to placebo, five (6.0%) had recurrent venous thromboembolism, compared with three of 81 (3.7%) assigned to warfarin, resulting in an absolute risk difference of 2.3%[95% confidence interval (CI) - 5.2, 10.0]. The incidence of recurrent venous thromboembolism after discontinuation of warfarin was 6.8% per patient-year in those who received warfarin for 1 month and 3.2% per patient-year in those who received warfarin for 3 months (rate difference of 3.6% per patient-year; 95% CI - 3.8, 11.0). There were no major bleeds in either group. CONCLUSION: Duration of anticoagulant therapy for venous thromboembolism provoked by a transient risk factor should not be reduced from 3 months to 1 month as this is likely to increase recurrent venous thromboembolism without achieving a clinically important decrease in bleeding.

Hypersulfated low molecular weight heparin with reduced affinity for antithrombin acts as an anticoagulant by inhibiting intrinsic tenase and prothrombinase.

In buffer systems, heparin and low molecular weight heparin (LMWH) directly inhibit the intrinsic factor X-activating complex (intrinsic tenase) but have no effect on the prothrombin-activating complex (prothrombinase). Although chemical modification of LMWH, to lower its affinity for antithrombin (LA-LMWH) has no effect on its ability to inhibit intrinsic tenase, N-desulfation of LMWH reduces its activity 12-fold. To further explore the role of sulfation, hypersulfated LA-LMWH was synthesized (sLA-LMWH). sLA-LMWH is not only a 32-fold more potent inhibitor of intrinsic tenase than LA-LMWH; it also acquires prothrombinase inhibitory activity. A direct correlation between the extent of sulfation of LA-LMWH and its inhibitory activity against intrinsic tenase and prothrombinase is observed. In plasma-based assays of tenase and prothrombinase, sLA-LMWH produces similar prolongation of clotting times in plasma depleted of antithrombin and/or heparin cofactor II as it does in control plasma. In contrast, heparin has no effect in antithrombin-depleted plasma. When the effect of sLA-LMWH on various components of tenase and prothrombinase was examined, its inhibitory activity was found to be cofactor-dependent (factors Va and VIIIa) and phospholipid-independent. These studies reveal that sLA-LMWH acts as a potent antithrombin-independent inhibitor of coagulation by attenuating intrinsic tenase and prothrombinase.

Thrombosis and anticoagulation.

Most of the major advances in thrombosis research have occurred in the last 50 years, reflecting progress in biomedical sciences and clinical trials methodology. Improved understanding of the mechanisms of thrombogenesis has led to the discovery of a plethora of new antithrombotic agents that target many of the key steps in blood coagulation and platelet activation. Although most of these compounds are still under development, low-molecular-weight heparins (LMWH), glycoprotein (GP) IIb/IIIa receptor antagonists, and inhibitors of the adenosine diphosphate (ADP) receptor on platelets have already established their niche in the clinic. The vessel wall has emerged as a major player, both in protecting against and in promoting thrombosis, and as we approach the new millennium, compounds are being developed that have the potential to prevent and treat thrombosis by modulating vessel wall function.

Identification of a unique glomerular factor X activator in murine lupus nephritis.

The role of glomerular procoagulant activity (PCA) was studied in mice (MRL/lpr, NZBxWF,, and BXSB) that are known to develop lupus nephritis. In young mice (6 to 8 wk) without renal disease, there was no increase in spontaneous glomerular PCA. In contrast, older (5 to 8 mo) autoimmune mice had significant augmentation in glomerular PCA, coinciding with the histologic appearance of severe glomerulonephritis and renal fibrin deposition. The PCA was characterized as a serine protease that directly activated factor X. This factor X activator is not tissue factor because (1) expression of PCA was not dependent on factor VII; (2) a monoclonal antibody against the factor X activator inhibited glomerular PCA, but not tissue factor; (3) the molecular weight (66 kD) of the activator was different from that of tissue factor; and (4) concanavalin A inhibited tissue factor but not glomerular PCA. Immunohistochemical studies localized the factor X activator to the glomerular mesangium and capillary wall of 4- to 6-mo-old diseased MRL/lpr mice. Immunogold-labeled antibody bound to the dense deposits, macrophages, and endothelial cells of diseased glomeruli. These studies define the role of a unique glomerular factor X activator in murine lupus nephritis.

Clinical utility of a rapid whole-blood D-dimer assay in patients with cancer who present with suspected acute deep venous thrombosis.

BACKGROUND: Although D-dimer assays have high negative predictive values for the diagnosis of deep venous thrombosis, their accuracy in patients with cancer is uncertain. OBJECTIVE: To compare the clinical utility of a whole-blood D-dimer assay for the diagnosis of deep venous thrombosis in patients with and those without cancer. DESIGN: Retrospective analysis of three prospective studies. SETTING: Two tertiary care hospitals. PATIENTS: 1068 consecutive outpatients with suspected deep venous thrombosis. MEASUREMENTS: All patients underwent D-dimer testing and assessment with a priori diagnostic strategies that incorporated impedance plethysmography, compression ultrasonography, or contrast venography. Patients in whom deep venous thrombosis was not diagnosed initially were followed for 3 months for the development of thrombosis. Results of D-dimer testing were assessed according to the final diagnosis based on objective testing and clinical follow-up. Cancer status was identified at presentation. RESULTS: The prevalence of deep venous thrombosis was 48.8% in 121 patients with cancer and 14.6% in 947 patients without cancer. Although the sensitivity of the D-dimer assay was similar in patients with and those without cancer (86.4% [95% CI, 75.0% to 94.0%] and 82.6% [CI, 75.2% to 88.5%], respectively), the specificity was significantly lower in patients with cancer (48.4% [CI, 35.5% to 61.4%] and 82.2% [CI, 79.4% to 84.8%]), as was the negative predictive value (78.9% [CI, 62.7% to 90.4%] and 96.5% [CI, 94.9% to 97.8%]). In contrast, the likelihood ratios of a negative test result (0.28 [CI, 0.14 to 0.56] and 0.21 [CI, 0.15 to 0.31]) did not differ significantly. CONCLUSIONS: A negative D-dimer test result in patients with cancer does not reliably exclude deep venous thrombosis because the negative predictive value of the test is significantly lower in these patients than in patients without cancer.

Comparison of heparin- and dermatan sulfate-mediated catalysis of thrombin inactivation by heparin cofactor II.

Heparin and dermatan sulfate activate heparin cofactor II (HCII) comparably, presumably by liberating the amino terminus of HCII to bind to exosite I of thrombin. To explore this model of activation, we systematically substituted basic residues in the glycosaminoglycan-binding domain of HCII with neutral amino acids and measured the rates of thrombin inactivation by the mutants. Mutant D, with changes at Arg(184), Lys(185), Arg(189), Arg(192), Arg(193), demonstrated a approximately 130-fold increased rate of thrombin inactivation that was unaffected by the presence of glycosaminoglycans. The increased rate reflects displacement of the amino terminus of mutant D because (a) mutant D inactivates gamma-thrombin at a 65-fold slower rate than alpha-thrombin, (b) hirudin-(54-65) decreases the rate of thrombin inactivation, and (c) deletion of the amino terminus of mutant D reduces the rate of thrombin inactivation approximately 100-fold. We also examined the contribution of glycosaminoglycan-mediated bridging of thrombin to HCII to the inhibitory process. Whereas activation of HCII by heparin was chain-length dependent, stimulation by dermatan sulfate was not, suggesting that dermatan sulfate does not utilize a template mechanism to accelerate the inhibitory process. Fluorescence spectroscopy revealed that dermatan sulfate evokes greater conformational changes in HCII than heparin, suggesting that dermatan sulfate stimulates HCII by producing more effective displacement of the amino terminus.

New antithrombotic agents.

The development of new antithrombotic agents has been stimulated by clinical needs and by advances in biotechnology that have made it possible to produce drugs that target specific steps in thrombogenesis. Heparin has pharmacokinetic and biophysical limitations that are overcome by new anticoagulants. Of these, low-molecular-weight heparin and direct inhibitors of thrombin have been evaluated clinically. Coumarins require careful laboratory monitoring because of concerns about safety. Orally active direct inhibitors of thrombin and factor Xa may replace coumarins. Aspirin is of limited efficacy because it inhibits only one pathway of platelet activation. Inhibitors of adenosine diphosphate receptor and glycoprotein IIb/IIIa antagonists are more effective than aspirin and are used in the clinic.

Long-term oral anticoagulant therapy in patients with unstable angina or suspected non-Q-wave myocardial infarction: organization to assess strategies for ischemic syndromes (OASIS) pilot study results.

BACKGROUND: Patients with acute ischemic syndromes (AIS) suffer high rates of recurrent ischemic events despite aspirin treatment. Long-term therapy with oral anticoagulants in addition to aspirin may reduce this risk. We studied the effects of long-term warfarin at 2 intensities in patients with AIS without ST elevation in 2 consecutive randomized controlled studies. METHODS AND RESULTS: In phase 1, after the cessation of 3 days of intravenous antithrombotic therapy, 309 patients were randomized to receive fixed low-dose (3 mg/d) warfarin for 6 months that produced a mean international normalized ratio (INR) of 1.5+/-0.6 or to standard therapy. Eighty-seven percent of patients received aspirin in both groups. The rates of cardiovascular (CV) death, new myocardial infarction (MI), and refractory angina at 6 months were 6.5% in the warfarin group and 3.9% in the standard therapy group (relative risk [RR], 1. 66; 95% CI, 0.62 to 4.44; P=0.31). The rates of death, new MI, and stroke were 6.5% in the warfarin group and 2.6% in the standard therapy group (RR, 2.48; 95% CI, 0.80 to 7.75; P=0.10). The overall rate of rehospitalization for unstable angina was 21% and did not differ significantly between the groups. Four patients in the warfarin group (2.6%) and none in the control group experienced a major bleed (RR, 2.48; 95% CI, 0.80 to 7.75), and there was a significant excess of minor bleeds in the warfarin group (14.2% versus 2.6%; RR, 5.46; 95% CI, 1.93 to 15.5; P=0.001). In phase 2, the protocol was modified, and 197 patients were randomized <48 hours from the onset of symptoms to receive warfarin at an adjusted dose that produced a mean INR of 2.3+/-0.6 or standard therapy for 3 months. Eighty-five percent received aspirin in both groups. The rates of CV death, new MI, and refractory angina at 3 months were 5. 1% in the warfarin group and 12.1% in the standard group (RR, 0.42; 95% CI, 0.15 to 1.15; P=0.08). The rates of all death, new MI, and stroke were 5.1% in the warfarin group and 13.1% in the standard therapy group (RR, 0.39; 95% CI, 0.14 to 1.05; P=0.05). Significantly fewer patients were rehospitalized for unstable angina in the warfarin group than in the control group (7.1% and 17.2%, respectively; RR, 0.42; 95% CI, 0.18 to 0.96; P=0.03). Two patients in the warfarin group and 1 in the control group experienced a major bleed, and there was a significant excess of minor bleeds in the warfarin group (28.6% versus 12.1%; RR, 2.36; 95% CI, 1.37 to 4.36; P=0.004). CONCLUSIONS: Long-term treatment with moderate-intensity warfarin (INR, 2.0 to 2.5) plus aspirin but not low-intensity warfarin (INR, 1.5) plus aspirin appears to reduce the rate of recurrent ischemic events in patients with AIS without ST elevation.