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

Pharmacotherapy and revascularization strategies of peripheral artery disease

The global epidemiological transition of atherosclerotic vascular diseases is witnessing a rapid redistribution of its burden, shifting from high-income to low- and middle-income countries. With a wide clinical spectrum, spanning from intermittent claudication to more complex critical limb threatening ischemia, nonhealing ulcers, gangrene as well as acute limb ischemia, peripheral artery disease is often faced with the challenges of under-diagnosis and under-treatment despite its high prevalence. The management of peripheral arterial disease in patients with multiple comorbidities presents a formidable challenge and remains a pressing global health concern. In this review, we aim to provide an in-depth overview of the pathophysiology of peripheral artery disease and explore evidence-based management strategies encompassing pharmacological, lifestyle, interventional, and surgical approaches. By addressing these challenges, the review contributes to a better understanding of the evolving landscape of peripheral artery disease, offering insights into effective and holistic management strategies.

Medical Management of Peripheral Artery Disease

Peripheral artery disease (PAD) is a common type of atherosclerotic disease of the lower extremities associated with reduced quality of life and ambulatory capacity. Major adverse cardiovascular events and limb amputations are the leading cause of morbidity and mortality in this population. Optimal medical therapy is therefore critical in these patients to prevent adverse events. Risk factor modifications, including blood pressure control and smoking cessation, in addition to antithrombotic agents, peripheral vasodilators, and supervised exercise therapy are key pillars of medical therapy. Revascularization procedures represent key touch points between patients and health care providers and serve as opportunities to optimize medical therapy and improve long-term patency rates and outcomes. This review summarizes the aspects of medical therapy that all providers should be familiar with when caring for patients with PAD in the peri-revascularization period.

Anticoagulation in Patients with Ischaemic Heart Disease and Peripheral Arterial Disease: Clinical Implications of COMPASS Study

Patients with established cardiovascular disease may suffer further cardiovascular events, despite receiving optimal medical treatment. Although platelet inhibition plays a central role in the prevention of new events, the use of anticoagulant therapies to reduce events in atheromatous disease has, until recently, been overlooked. The recent Rivaroxaban for the Prevention of Major Cardiovascular Events in Coronary or Peripheral Artery Disease (COMPASS) study showed an important reduction in cardiovascular events without increasing the risk of fatal and intracranial bleeding when using rivaroxaban, a novel oral anticoagulant, combined with aspirin. This article reviews the available evidence regarding the use of anticoagulant therapies for prevention of cardiovascular events, the results of the COMPASS study and how these results may affect patient management in everyday clinical practice.

Efficacy and safety of aspirin combined with warfarin after acute coronary syndrome : A meta-analysis

A comprehensive meta-analysis was performed to investigate whether the combination of high-/low-dose of aspirin and various intensities of warfarin (W) offer greater benefit than aspirin (ASA) alone. A total of 14 randomized clinical trials (RCTs) having 26,916 patients with acute coronary syndrome (ACS) met inclusion criteria. The efficacy and safety of all outcomes which included myocardial infarction (MI), all-cause death, stroke, and bleeding were calculated. The overall outcomes analysis showed there was no significant difference in the risk of MI (relative ratio [RR] 0.959, 95 % confidence interval [CI] 0.78-1.04, P = 0.308), stroke (RR 0.789, 95 % CI 0.57-1.09, P = 0.145), and all-cause death (RR 1.007, 95 % CI 0.93-1.09, P = 0.87) between the combination group and ASA group. The subgroup analysis suggested that ASA (≤100 mg/day) plus W (mean international normalized ratio [INR] 2.0-3.0) decreased the risk rate of stroke (RR 0.660, 95 % CI 0.50-0.87, P = 0.003). There was a lower risk of MI (RR 0.605, 95 % CI 0.47-0.77, P < 0.0001) as well as stroke (RR 0.594, 95 % CI 0.45-0.79, P < 0.0001) between W (INR 2.0-3.0) combined with ASA (mean dose ≥100 mg/day) and ASA. However, the risk of major bleeding (RR 1.738, 95 % CI 1.45-2.08, P < 0.0001) and minor bleeding (RR 2.767, 95 % CI 2.12-3.61, P < 0.0001) was almost doubled in the combined groups. Compared with ASA, high-dose aspirin with moderate-intensity warfarin (INR 2.0-3.0) may better reduce the risk of MI and stroke but confer an increased risk of bleeding.

Complex antithrombotic therapy: determinants of patient preference and impact on medication adherence

PURPOSE

For years, older patients have been prescribed multiple blood-thinning medications (complex antithrombotic therapy [CAT]) to decrease their risk of cardiovascular events. These therapies, however, increase risk of adverse bleeding events. We assessed patient-reported trade-offs between cardioprotective benefit, gastrointestinal bleeding risk, and burden of self-management using adaptive conjoint analysis (ACA). As ACA could be a clinically useful tool to obtain patient preferences and guide future patient-centered care, we examined the clinical application of ACA to obtain patient preferences and the impact of ACA on medication adherence.

PATIENTS AND METHODS

An electronic ACA survey led 201 respondents through medication risk-benefit trade-offs, revealing patients' preferences for the CAT risk/benefit profile they valued most. The post-ACA prescription regimen was categorized as concordant or discordant with elicited preferences. Adherence was measured using VA pharmacy refill data to measure persistence of use prior to and 1 year following preference-elicitation. Additionally, we analyzed qualitative interviews of 56 respondents regarding their perception of the ACA and the preference elicitation experience.

RESULTS

Participants prioritized 5-year cardiovascular benefit over preventing adverse events. Medication side effects, medication-associated activity restrictions, and regimen complexity were less important than bleeding risk and cardioprotective benefit. One year after the ACA survey, a 15% increase in adherence was observed in patients prescribed a preference-concordant CAT strategy. An increase of only 6% was noted in patients prescribed a preference-discordant strategy. Qualitative interviews showed that the ACA exercise contributed to increase inpatient activation, patient awareness of preferences, and patient engagement with clinicians about treatment decisions.

CONCLUSION

By working through trade-offs, patients actively clarified their preferences, learning about CAT risks, benefits, and self-management. Patients with medication regimens concordant with their preferences had increased medication adherence at 1 year compared to those with discordant medication regimens. The ACA task improved adherence through enhanced patient engagement regarding treatment preferences.

Potential role of oral anticoagulants in the treatment of patients with coronary artery disease: focus on dabigatran

The pharmacologic management of patients with high-risk coronary artery disease consists of aspirin and a P2Y12 receptor inhibitor. Chronic oral anticoagulation with warfarin is the major treatment strategy to attenuate thromboembolism or stroke in patients with deep vein thrombosis, pulmonary embolism, heart failure and atrial fibrillation. A substantial percentage of the latter group of patients have coronary artery disease and may require stenting with long-term dual antiplatelet therapy in addition to therapy with warfarin to reduce arterial ischemic events in addition to stroke. These new oral anticoagulants have been developed for long-term therapy to overcome the limitations of warfarin. Dabigatran is a direct thrombin inhibitor and its role in patients with acute coronary syndrome is being explored.

Low-dose of oral factor Xa inhibitors in patients with a recent acute coronary syndrome: a systematic review and meta-analysis of randomized trials

BACKGROUND

Recently, randomized controlled trials (RCTs) have shown that therapy with new oral activated factor X (Xa) inhibitors in acute coronary syndrome (ACS) yielded a reduction of ischemic events. However, this therapy was associated with a dose-related increase in major bleeding complications. We aimed to perform a systematic review and meta-analysis to appraise the clinical efficacy and safety of the lowest doses of oral factor Xa inhibitors compared with placebo in patients after a recent ACS.

METHODS

The primary endpoint was cardiovascular mortality. The rate of new myocardial infarction (MI) was the secondary efficacy endpoint, whereas major bleeding complications were recorded as a safety endpoint. Five RCTs were included in the meta-analysis enrolling a total of 25,643 patients.

RESULTS

There was no significant difference in mortality between patients treated with new antithrombotics compared with those receiving the standard therapy: odds ratio (OR), [95% confidence interval (CI)] = 0.97 [0.72-1.31], p = 0.86. Recurrent MI rates were decreased in the anti-Xa group: OR [95%CI] = 0.86 [0.76-0.98], p = 0.02, number needed to treat (NNT) = 189. The administration of new oral anticoagulants was associated with a strongly increased risk of major bleedings compared with the standard treatment: OR [95%CI] = 3.24 [2.29-4.59], p < 0.001, number needed to harm (NNH) = 104; similarly, intracranial bleeding rates were significantly higher in the anti-Xa arm.

CONCLUSIONS

The addition of the new oral anticoagulants on top of standard therapy in the setting of ACS results in an excessive risk of major bleedings without any clear evidence of outweighing clinical benefits.

Potential role of rivaroxaban in patients with acute coronary syndrome

Patients with acute coronary syndrome (ACS) continue to be at risk for recurrent ischemic events, despite an early invasive strategy and the use of dual antiplatelet therapy. The anticoagulant pathway remains activated for a prolonged period after ACS and, consequently, has been a target for treatment. Early studies with warfarin indicated its benefit, but the risk of bleeding and the complexities of warfarin anticoagulation resulted in little use of this strategy. Rivaroxaban, apixaban, and dabigatran are new specific inhibitors of anticoagulant factors (Xa or IIa) currently available for the prevention of thrombosis and/or thromboembolism. Thus far, studies with dabigatran and apixaban in ACS have shown no clinical benefit and bleeding has been increased. The ATLAS ACS 2-TIMI 51 trial observed the impact of rivaroxaban 2.5 mg and 5 mg twice daily in patients with recent ACS receiving current management (both early invasive strategy and dual antiplatelet therapy with aspirin and clopidogrel) over a follow-up period of over 1 year. Rivaroxaban 2.5 mg twice daily reduced cardiovascular death, myocardial infarction, or stroke by 16%, and both cardiovascular and all-cause mortality by approximately 20%. Although major bleeding increased from 0.6% to 2.1% and intracranial hemorrhage from 0.2% to 0.6%, there was no increase in fatal bleeding. The role of rivaroxaban in the management of ACS is discussed in this review. The reduction in mortality is the main finding that could lead to the use of rivaroxaban in the management of ACS in high-risk individuals with a low bleeding risk.

Primary and secondary prevention of cardiovascular disease: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines

BACKGROUND

This guideline focuses on long-term administration of antithrombotic drugs designed for primary and secondary prevention of cardiovascular disease, including two new antiplatelet therapies.

METHODS

The methods of this guideline follow those described in Methodology for the Development of Antithrombotic Therapy and Prevention of Thrombosis Guidelines: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines in this supplement.

RESULTS

We present 23 recommendations for pertinent clinical questions. For primary prevention of cardiovascular disease, we suggest low-dose aspirin (75-100 mg/d) in patients aged > 50 years over no aspirin therapy (Grade 2B). For patients with established coronary artery disease, defined as patients 1-year post-acute coronary syndrome, with prior revascularization, coronary stenoses > 50% by coronary angiogram, and/or evidence for cardiac ischemia on diagnostic testing, we recommend long-term low-dose aspirin or clopidogrel (75 mg/d) (Grade 1A). For patients with acute coronary syndromes who undergo percutaneous coronary intervention (PCI) with stent placement, we recommend for the first year dual antiplatelet therapy with low-dose aspirin in combination with ticagrelor 90 mg bid, clopidogrel 75 mg/d, or prasugrel 10 mg/d over single antiplatelet therapy (Grade 1B). For patients undergoing elective PCI with stent placement, we recommend aspirin (75-325 mg/d) and clopidogrel for a minimum duration of 1 month (bare-metal stents) or 3 to 6 months (drug-eluting stents) (Grade 1A). We suggest continuing low-dose aspirin plus clopidogrel for 12 months for all stents (Grade 2C). Thereafter, we recommend single antiplatelet therapy over continuation of dual antiplatelet therapy (Grade 1B).

CONCLUSIONS

Recommendations continue to favor single antiplatelet therapy for patients with established coronary artery disease. For patients with acute coronary syndromes or undergoing elective PCI with stent placement, dual antiplatelet therapy for up to 1 year is warranted.

The association between prior use of aspirin and/or warfarin and the in-hospital management and outcomes in patients presenting with acute coronary syndromes: insights from the Global Registry of Acute Coronary Events (GRACE)

BACKGROUND

The role of acetylsalicylic acid (ASA [aspirin]) and warfarin in secondary prevention after acute coronary syndromes (ACS) is well established. However, there are sparse data comparing the presentation and outcomes of patients who present with ACS while on ASA and/or warfarin therapy and those on neither.

METHODS

Using data from the Canadian Global Registry of Acute Coronary Events (GRACE), we stratified 14,090 ACS patients into 4 groups according to prior use of antithrombotic therapies and compared in-hospital management and outcomes.

RESULTS

Among 14,090 ACS patients, 7411 (52.6%) were not on prior ASA or warfarin therapy, 5724 (40.6%) were on ASA only, 593 (4.2%) were on warfarin only, and 362 (2.6%) were on both ASA and warfarin. ACS patients taking ASA and/or warfarin were older with more comorbidities than the patients on neither drug. Patients receiving prior warfarin only or ASA and warfarin were less likely to receive guideline-recommended therapies. Patients who were taking prior warfarin only had higher unadjusted rates of death, death and/or reinfarction (re-MI), congestive heart failure (CHF), and major bleeding as compared with patients on no prior therapy. Furthermore, patients who were taking ASA and warfarin had higher unadjusted rates of death and/or re-MI and CHF than patients on prior ASA only.

CONCLUSIONS

ACS patients on prior warfarin are a high-risk population, yet they receive less guideline-recommended therapies and have higher unadjusted adverse event rates during their index hospitalization. With the increasing use of oral anticoagulants, clinical trials are needed to guide the optimal management of these ACS patients.

Low doses of acetylsalicylic acid increase risk of gastrointestinal bleeding in a meta-analysis

BACKGROUND & AIMS

We performed a meta-analysis of data from randomized trials to estimate the risk of all-cause mortality and bleeding (and especially gastrointestinal [GI] bleeding) in patients treated with low doses of acetylsalicylic acid (ASA) (75-325 mg/d), alone or in combination with other medications.

METHODS

We searched 10 electronic databases (until October 2010) and collected data on adverse events in randomized controlled studies that evaluated low doses of ASA, alone (35 trials) or in combination with anticoagulants (18 trials), clopidogrel (5 trials), or proton pump inhibitors (PPIs; 3 trials). We analyzed data using random-effects meta-analysis and meta-regression, applying Peto's odds ratio (OR) for adverse events.

RESULTS

Low doses of ASA alone decreased the risk for all-cause mortality (relative risk, 0.93, 95% confidence interval [CI], 0.87-0.99), largely because of effects in secondary prevention populations. The risk of major GI bleeding increased with low doses of ASA alone (OR, 1.55; 95% CI, 1.27-1.90), compared with inert control reagents. The risk increased when ASA was combined with clopidogrel, compared with aspirin alone (OR, 1.86; 95% CI, 1.49-2.31), anticoagulants vs low doses of ASA alone (OR, 1.93; 95% CI, 1.42-2.61), or in studies that included patients with a history of GI bleeding or of longer duration. Importantly, PPI use reduced the risk for major GI bleeding in patients given low doses of ASA (OR, 0.34; 95% CI, 0.21-0.57).

CONCLUSIONS

In a meta-analysis, low doses of ASA increased the risk for GI bleeding; risk increased with accompanying use of clopidogrel and anticoagulant therapies, but decreased in patients who took PPIs.

Long-term effect of chronic oral anticoagulation with warfarin after acute myocardial infarction

BACKGROUND

Antiplatelet therapy is the principal component of the antithrombotic regimen after acute myocardial infarction. It remains unclear whether additional chronic oral anticoagulation (OAC) improves outcomes. We set out to evaluate the risk and benefit of long-term OAC after myocardial infarction.

METHODS

We pooled 10 randomized clinical trials comparing warfarin-containing regimens (OAC) with or without aspirin with non-OAC regimens with or without aspirin (No OAC) for patients with recent infarction. The primary endpoint was all-cause mortality. Other endpoints included recurrent infarction, stroke, and major bleeding. We calculated the odds ratio (OR) (fixed effect, OR <1 indicates benefit for OAC) for death and other ischemic and hemorrhagic complications at the longest interval of follow-up available.

RESULTS

Among 24,542 patients, 14,062 were assigned to OAC and 10,480 to no OAC. The patients were followed for 3-63 months, for 89,562 patient-years. Death occurred in 2424 patients (9.9%), 1279 OAC patients, and 1145 in the no OAC group, OR 0.97 (95% confidence interval [CI], 0.88-1.05), P=.43. Similarly, there was no effect on recurrent infarction. Stroke occurred in 578 patients (2.4%), 271 in the OAC group and 307 in the no OAC group, OR 0.75 (95% CI, 0.63-0.89), P=.001. There was substantially more major bleeding (OR 1.83 [95% CI, 1.50-2.23], P <.001) in the OAC group. Separate analyses, performed for patients (n=11,920) randomized to aspirin versus aspirin and OAC yielded very similar results.

CONCLUSION

As compared with placebo or aspirin, OAC with or without aspirin does not reduce mortality or reinfarction, reduces stroke, but is associated with significantly more major bleeding.

Evaluating the benefit of event adjudication of cardiovascular outcomes in large simple RCTs

BACKGROUND

Event adjudication in randomized controlled trials is thought to be a necessary step to remove noise and potential bias from the results [1,2]. However, this hypothesis has not been widely evaluated. We conducted a meta-analysis of a series of cardiovascular outcomes trials and estimated the effect of adjudication on treatment estimates and on the number of outcomes included the trials.

METHODS

Data were retrieved from all cardiovascular outcomes trials conducted at the Population Health Research Institute (PHRI) between 1993 and 2006. These data included 10 trials with over 9000 events from 95,038 individuals. Differences in the log odds ratios between adjudicated and reported outcomes were analyzed and summarized using a ratio of odds ratios. Both masked and unmasked trials were included in this analysis.

RESULTS

There were no effects of event adjudication on the estimates of treatment effect for the primary outcomes, myocardial infarction (MI), stroke, or cardiovascular/vascular death. For the trial primary outcomes, the effect of adjudication vs. reported events was OR ratio = 1.00 [95% confidence interval (CI): 0.97-1.02]. There were also no significant differences in the number of outcomes included in the trials. Results were the same for masked and unmasked trials.

LIMITATIONS

The number of unmasked trials were small, and this analysis was restricted to cardiovascular endpoints reported from trials managed by a single coordinating center, with similar sets of procedures. Individual patient data were not used for the analysis.

CONCLUSIONS

This systematic meta-analysis failed to detect any effect of event adjudication on study conclusions and the numbers of events included in the final analyses were minimally changed. Given the considerable effort required to perform adjudication, there is a need to demonstrate that this process does indeed increase the sensitivity of trials. There is a need to conduct more systematic analyses of the effect of event adjudication in other trials to determine if this process is truly worthwhile.

Rivaroxaban versus placebo in patients with acute coronary syndromes (ATLAS ACS-TIMI 46): a randomised, double-blind, phase II trial

BACKGROUND

Rivaroxaban is an oral direct factor Xa inhibitor that has been effective in prevention of venous thromboembolism in patients undergoing elective orthopaedic surgery. However, its use after acute coronary syndromes has not been investigated. In this setting, we assessed the safety and efficacy of rivaroxaban and aimed to select the most favourable dose and dosing regimen.

METHODS

In this double-blind, dose-escalation, phase II study, undertaken at 297 sites in 27 countries, 3491 patients stabilised after an acute coronary syndrome were stratified on the basis of investigator decision to use aspirin only (stratum 1, n=761) or aspirin plus a thienopyridine (stratum 2, n=2730). Participants were randomised within each strata and dose tier with a block randomisation method at 1:1:1 to receive either placebo or rivaroxaban (at doses 5-20 mg) given once daily or the same total daily dose given twice daily. The primary safety endpoint was clinically significant bleeding (TIMI major, TIMI minor, or requiring medical attention); the primary efficacy endpoint was death, myocardial infarction, stroke, or severe recurrent ischaemia requiring revascularisation during 6 months. Safety analyses included all participants who received at least one dose of study drug; efficacy analyses were by intention to treat. This study is registered with ClinicalTrials.gov, number NCT00402597.

FINDINGS

Three patients in stratum 1 and 26 in stratum 2 never received the study drug. The risk of clinically significant bleeding with rivaroxaban versus placebo increased in a dose-dependent manner (hazard ratios [HRs] 2.21 [95% CI 1.25-3.91] for 5 mg, 3.35 [2.31-4.87] for 10 mg, 3.60 [2.32-5.58] for 15 mg, and 5.06 [3.45-7.42] for 20 mg doses; p<0.0001). Rates of the primary efficacy endpoint were 5.6% (126/2331) for rivaroxaban versus 7.0% (79/1160) for placebo (HR 0.79 [0.60-1.05], p=0.10). Rivaroxaban reduced the main secondary efficacy endpoint of death, myocardial infarction, or stroke compared with placebo (87/2331 [3.9%] vs 62/1160 [5.5%]; HR 0.69, [95% CI 0.50-0.96], p=0.0270). The most common adverse event in both groups was chest pain (248/2309 [10.7%] vs 118/1153 [10.2%]).

INTERPRETATION

The use of an oral factor Xa inhibitor in patients stabilised after an acute coronary syndrome increases bleeding in a dose-dependent manner and might reduce major ischaemic outcomes. On the basis of these observations, a phase III study of low-dose rivaroxaban as adjunctive therapy in these patients is underway.

FUNDING

Johnson & Johnson Pharmaceutical Research & Development and Bayer Healthcare AG.

Anticoagulants in coronary artery disease

Anticoagulant therapy for acute coronary syndromes is becoming more complex as newer agents are added to unfractionated heparin and warfarin. The anticoagulants used in current clinical practice are low molecular weight heparins, direct thrombin inhibitors, and heparinoids. Properties of and recent clinical trial data regarding these newer anticoagulants are reviewed in reference to current American College of Cardiology/American Heart Association guidelines.

Management strategies in unstable coronary artery disease--current problems and future directions. The UCAD Council

Unstable coronary artery disease continues to pose a major challenge to clinicians. The advent of new therapies, such as percutaneous transluminal coronary angioplasty, low-molecular-weight heparins, and glycoprotein IIb/IIIa inhibitors, provides new management options for this indication but also raises new questions with regard to optimal management. Prospective randomized trials with well-defined, long-term outcome measures and a means of identifying which patients will derive most benefit from each treatment, together with a means of rapid and clear dissemination of study results and implications, are required in order to advance the management of unstable coronary artery disease.

The primary and secondary prevention of coronary artery disease: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition)

The following chapter devoted to antithrombotic therapy for chronic coronary artery disease (CAD) is part of the Antithrombotic and Thrombolytic Therapy: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition). Grade 1 recommendations are strong and indicate that the benefits do or do not outweigh risks, burden, and costs. Grade 2 suggests that individual patient values may lead to different choices (for a full understanding of the grading see the "Grades of Recommendation" chapter by Guyatt et al in this supplement, CHEST 2008; 133[suppl]:123S-131S). Among the key recommendations in this chapter are the following: for patients with non-ST-segment elevation (NSTE)-acute coronary syndrome (ACS) we recommend daily oral aspirin (75-100 mg) [Grade 1A]. For patients with an aspirin allergy, we recommend clopidogrel, 75 mg/d (Grade 1A). For patients who have received clopidogrel and are scheduled for coronary bypass surgery, we suggest discontinuing clopidogrel for 5 days prior to the scheduled surgery (Grade 2A). For patients after myocardial infarction, after ACS, and those with stable CAD and patients after percutaneous coronary intervention (PCI), we recommend daily aspirin (75-100 mg) as indefinite therapy (Grade 1A). We recommend clopidogrel in combination with aspirin for patients experiencing ST-segment elevation (STE) and NSTE-ACS (Grade 1A). For patients with contraindications to aspirin, we recommend clopidogrel as monotherapy (Grade 1A). For long-term treatment after PCI in patients who receive antithrombotic agents such as clopidogrel or warfarin, we recommend aspirin (75 to 100 mg/d) [Grade 1B]. For patients who undergo bare metal stent placement, we recommend the combination of aspirin and clopidogrel for at least 4 weeks (Grade 1A). We recommend that patients receiving drug-eluting stents (DES) receive aspirin (325 mg/d for 3 months followed by 75-100 mg/d) and clopidogrel 75 mg/d for a minimum of 12 months (Grade 2B). For primary prevention in patients with moderate risk for a coronary event, we recommend aspirin, 75-100 mg/d, over either no antithrombotic therapy or vitamin K antagonist (Grade 1A).

Chronic antithrombotic therapy in post-myocardial infarction patients

Because 1.1 million myocardial infarctions occur in the United States alone each year, and 450,000 of them are recurrent infarctions, which carry an inherently greater risk of death and disability than first events, the importance of secondary prevention strategies that can be implemented widely is unparalleled in health care. Antithrombotic therapies, both antiplatelet and anticoagulant, have become the mainstays of these strategies. This article covers the use of chronic antiplatelet and anticoagulation agents after myocardial infarction. It does not include the management of these patients in the acute phase.

Aspirin, clopidogrel, and warfarin: is the combination appropriate and effective or inappropriate and too dangerous?

OBJECTIVE

To review the rationale, clinical practice guideline recommendations, and clinical trial data describing bleeding and clinical outcomes associated with the use of the combination of aspirin, a thienopyridine, and warfarin.

DATA SOURCES

An English-language literature search was conducted using MEDLINE (1966-March 2008) and the search terms aspirin, clopidogrel, ticlopidine, thienopyridine, warfarin, antiplatelet, anticoagulant, myocardial infarction, atrial fibrillation, and percutaneous coronary intervention (PCI). Additional references were identified by reviewing reference citations of articles retrieved.

STUDY SELECTION AND DATA EXTRACTION

Applicable data were extracted from published reports and studies that included either clinical outcomes or adverse events.

DATA SYNTHESIS

Clinical guidelines recommend the combination of antiplatelets and anticoagulants based largely on writing committee consensus. To date, only one randomized clinical trial has evaluated the safety and efficacy of adding warfarin to dual antiplatelet therapy (ie, triple antithrombotic therapy). Other published data are from case series, observational studies, and case-controlled studies primarily of patients undergoing PCI with intracoronary stent placement. Four of 12 studies reported no increased risk of major bleeding events. In the other 8 studies, a 3- to 6-fold increase in bleeding events was reported with triple antithrombotic therapy. Ischemic events were reported in only 6 of the studies. Only 2 studies observed an additional benefit in the reduction of ischemic events, and 1 study reported worsened ischemic outcomes with the triple antithrombotic regimen compared with dual antithrombotic therapy.

CONCLUSIONS

Available guidelines pertaining to the concomitant administration of aspirin, a thienopyridine, and warfarin are based on limited trial data and consensus judgment. Overall, selection of triple antithrombotic therapy for patients with vascular disease is considered a matter of clinical judgment for an individual patient based on the prescriber's perceived balance between the patient's risk for recurrent ischemic events, expected duration of treatment, and patient's risk for bleeding.

Adjusted Indirect Meta-Analysis of Aspirin Plus Warfarin at International Normalized Ratios 2 to 3 Versus Aspirin Plus Clopidogrel After Acute Coronary Syndromes

After acute coronary syndromes, the beneficial effect of aspirin plus clopidogrel (A+C) or aspirin plus dose-adjusted warfarin (A+W) compared with aspirin alone is well established. However, these regimens were never compared. To compare the risk-benefit profile of A+C versus A+W after acute coronary syndromes, major medical databases for randomized controlled trials comparing 1 of these combined approaches versus aspirin alone after an acute coronary syndrome (updated June 2006) were searched. Evaluated end points were major adverse events [MAEs: all-cause death, acute myocardial infarction [AMI], thromboembolic stroke, major bleeds, and overall risk of stroke [hemorrhagic or ischemic]). Odds ratios (ORs) with 95% confidence intervals (CIs) were calculated for (1) A+W versus aspirin alone, (2) A+C versus aspirin alone, and (3) A+W versus A+C using adjusted indirect meta-analysis. Thirteen studies were included, totaling 69,741 patients. Ten compared A+W versus aspirin alone and 3 compared A+C versus aspirin alone. Each combined approach yielded a significantly lower risk of MAEs, albeit an increased risk of major bleeds, compared with aspirin alone. No significant difference was found for A+W versus A+C for risk of overall MAEs, death, or AMI. However, A+W versus A+C was associated with a significantly lower risk of thromboembolic stroke (OR 0.53, 95% CI 0.31 to 0.88, number needed to treat 60) and all types of stroke (OR 0.58, 95% CI 0.35 to 0.94, p=0.038), but also with increased risk of major bleeds (OR 1.9, 95% CI 1.2 to 2.8, number needed to harm 300). In conclusion, after an acute coronary syndrome, A+W and A+C are comparable in the prevention of MAEs, death, and AMI compared with aspirin alone. Allocating 100 patients to A+W (at international normalized ratio 2 to 3) with respect to A+C could prevent 17 thromboembolic strokes while causing 3 major bleeds.

Evidence-based medical therapy of patients with acute coronary syndromes

Acute coronary syndromes (ACS) present a major health challenge in modern medicine. With new clinical trials being conducted, our knowledge of latest therapies for ACS continually evolves. In this article, we review currently available medical therapies and provide evidence-based rationale for current pharmacologic therapies. Among the antiplatelet therapies, aspirin, clopidogrel, and glycoprotein IIb/IIIa inhibitors demonstrate significant efficacy in reducing morbidity and mortality. Among the anticoagulants, unfractionated heparin and low molecular weight heparin, particularly enoxaparin sodium, remain the hallmarks of therapy against which newer anticoagulants are often compared. Bivalirudin has recently showed significant efficacy in decreasing cardiovascular events and mortality, but with potentially less risk of bleeding than heparin. Results of trials evaluating warfarin remain inconsistent regarding potential benefits. Finally, fondaparinux sodium, recently tested, shows promise as a powerful yet safe anticoagulant. Fibrinolysis is an acceptable modality for reperfusion if facilities equipped for primary percutaneous revascularization are not available. Regarding anti-ischemic therapy, beta-adrenoceptor antagonists and nitrates remain critical in the early management of ACS. Inhibitors of the renin-angiotensin-aldosterone system have also shown significant reductions in the morbidity and mortality of patients presenting with ACS, particularly in patients with left ventricular dysfunction and clinical heart failure, with ACE inhibitors being first-line agents and angiotensin receptor antagonists being a reasonable substitute if ACE inhibitors are not tolerated. Among the lipid-lowering therapies, statins (HMG-CoA reductase inhibitors) have been documented as being the most well tolerated and most efficacious therapies for ACS patients and data exist that they should be administered early in ACS management. Studies evaluating combination therapy (antiplatelet drugs, beta-adrenoceptor antagonists, ACE inhibitors, and lipid-lowering agents) show a clear benefit in mortality in patients with known coronary artery disease. Efforts to improve these key evidence-based medical therapies are numerous and include such programs as the American College of Cardiology's Guidelines Applied in Practice, international patient registries such as the Global Registry of Acute Coronary Events, and studies such as CRUSADE. Finally, patients with diabetes mellitus pose a challenge to clinicians both in terms of their glycemic control and in their apparent relative resistance to antiplatelet therapy. Studies involving ACS patients suggest that stringent glycemic control may result in benefits in both morbidity and mortality.

Aspirin, Warfarin and a Thienopyridine for Acute Coronary Syndromes

BACKGROUND

Although clopidogrel and aspirin (dual therapy, DT) are used for acute coronary syndrome (ACS), sometimes treatment with warfarin (triple therapy, TT) is required.

AIM

To determine the incidence, complications, and outcomes of TT.

METHODS

We analyzed Israeli surveys of ACS from 2000 to 2004.

RESULTS

In these surveys, 5,706 (96%) were discharged alive from hospital. Post-ACS TT and DT were 76 patients (1.3%) and 2,661 patients (46.7%), respectively. The TT group was older with more prior cardiac disease. During hospitalization, the TT patients received more intravenous anticoagulant and antithrombotic agents, and had more heart failure, arrhythmias, ischemia, and major bleeding (2.6 vs. 0.6%, p=0.03). There were no differences in adjusted 30-day and 6-month mortality between the 2 groups.

CONCLUSION

TT is feasible among ACS patients who require concomitant warfarin treatment.

Chronic Antithrombotic Therapy in Post–Myocardial Infarction Patients

Recent advances in the acute treatment of myocardial infarction (MI) have allowed more to survive the initial event in coronary artery disease. Increasing importance has been placed on secondary-prevention strategies, with more attention directed toward an optimal therapeutic regimen for post-MI patients. When it comes to the subpopulation of the elderly who have had an MI, however, current practice relies less on population-specific evidence and more on extrapolation of current data. This article reviews the pathogenesis of coronary heart disease and MI, and highlights recent major trials that have explored antiplatelet and anticoagulant medications in the chronic treatment of the post-MI population. Special consideration is given to the geriatric community and its unique challenge regarding chronic antithrombotic therapy.

Aspirin plus warfarin compared to aspirin alone after acute coronary syndromes: an updated and comprehensive meta-analysis of 25,307 patients

AIMS

In patients recovering from acute coronary syndromes (ACS) the role of oral anticoagulation (and its intensity) in addition to aspirin remains controversial. We conducted a specific meta-analysis of randomized trials comparing aspirin plus warfarin (A+W) with aspirin alone in such patients.

METHODS AND RESULTS

MEDLINE and Cochrane databases yielded 14 (of 148 potentially relevant) articles enrolling 25 307 patients. Follow-up ranged from 3 months to 5 years. Irrespective of International normalized ratio (INR), A+W did not significantly affect the risk of major adverse events (MAE: all cause death, non-fatal myocardial infarction, and non-fatal thrombo-embolic stroke) when compared with aspirin alone [OR 0.96 (0.90-1.03), P=0.30], but increased the risk of major bleeds (MB): OR 1.77 (1.47-2.13), P<0.00001. However, in studies with INR of 2-3, A+W was associated with a significant reduction of MAE [OR 0.73 (0.63-0.84), P<0.0001, number needed to treat to avoid one MAE=33], albeit at an increased risk of MB [OR 2.32 (1.63-3.29), P<0.00001; number needed to harm by causing one MB=100]. In both analyses, intracranial bleeding was not significantly increased by A+W when compared with aspirin alone.

CONCLUSION

For patients recovering from ACS, a combined strategy of A+W at INR values of 2-3 doubles the risk of MB, but is nonetheless superior to aspirin alone in preventing MAE. Whether this combined regimen is also superior to a 'double' anti-platelet strategy or to newer evolving treatments warrants further investigation.

Direct thrombin inhibitors: current status and future prospects

Thrombin is a pivotal enzyme in the coagulation cascade and in the pathogenesis of thrombosis, which can lead to the occurrence of a number of coronary syndromes. Thrombin inhibition, by either recombinant or synthetic inhibitors, has now been recognised as a possible mechanism by which to modulate thrombosis; a cause of considerable mortality and morbidity, particularly in the western world. This approach represents a departure from established antithrombotic therapy, the mainstay therapies for which are aspirin, heparin or warfarin. There is now a body of clinical evidence with recombinant peptide or protein based thrombin inhibitors, and, to a lesser extent, synthetic agents, which give useful insights into the potential therapeutic impact of direct thrombin inhibitors. As well as defining the key clinical parameters where these drugs can be beneficial, clinical studies have also highlighted specific areas which need to be addressed by newer compounds in this class. A number of examples of low molecular weight and potentially orally available compounds are now in early clinical development; they may serve to answer many of the questions raised by Phase III trials with compounds based on hirudin.

What causes acute coronary syndromes? Applying Koch's postulates

The term "acute coronary syndromes" (ACS) is used to describe a heterogeneous spectrum of clinical conditions. This includes myocardial infarction, non-ST-elevation myocardial infarction, and unstable angina. These conditions are linked by a similar constellation of signs and symptoms but not necessarily by a common pathophysiology. They are syndromes. Several different hypotheses exist that have attempted to explain the pathological mechanisms that are involved in these conditions, however, it is not clear whether ACS are caused by variations of a single disease process or by several disease processes. The contribution of both vessel wall- and blood-related factors in the pathogenesis of acute coronary syndromes is herein discussed with the guidance of Koch's postulates.

Antithrombotic therapy for coronary artery disease: the Seventh ACCP Conference on Antithrombotic and Thrombolytic Therapy

This chapter about antithrombotic therapy for coronary artery disease (CAD) is part of the Seventh ACCP Conference on Antithrombotic and Thrombolytic Therapy: Evidence Based Guidelines. Grade 1 recommendations are strong and indicate that the benefits do, or do not, outweigh risks, burden, and costs. Grade 2 suggests that individual patients' values may lead to different choices (for a full understanding of the grading see Guyatt et al, CHEST 2004; 126:179S-187S). Among the key recommendations in this chapter are the following: For patients presenting with non-ST-segment elevation (NSTE) acute coronary syndrome (ACS), we recommend immediate and then daily oral aspirin (Grade 1A). For patients with an aspirin allergy, we recommend immediate treatment with clopidogrel, 300-mg bolus po, followed by 75 mg/d indefinitely (Grade 1A). In all NSTE ACS patients in whom diagnostic catheterization will be delayed or when coronary bypass surgery will not occur until > 5 days, we recommend clopidogrel as bolus therapy (300 mg), followed by 75 mg/d for 9 to 12 months in addition to aspirin (Grade 1A). In NSTE ACS patients in whom angiography will take place within 24 h, we suggest beginning clopidogrel after the coronary anatomy has been determined (Grade 2A). For patients who have received clopidogrel and are scheduled for coronary bypass surgery, we recommend discontinuing clopidogrel for 5 days prior to the scheduled surgery (Grade 2A). In moderate- to high-risk patients presenting with NSTE ACS, we recommend either eptifibatide or tirofiban for initial (early) treatment in addition to treatment with aspirin and heparin (Grade 1A). For the acute treatment of NSTE ACS, we recommend low molecular weight heparins over unfractionated heparin (UFH) [Grade 1B] and UFH over no heparin therapy use with antiplatelet therapies (Grade 1A). We recommend against the direct thrombin inhibitors as routine initial antithrombin therapy (Grade 1B). For patients after myocardial infarction, after ACS, and with stable CAD, we recommend aspirin in doses from 75 to 325 mg as initial therapy and in doses of 75 to 162 mg as indefinite therapy (Grade 1A). For patients with contraindications to aspirin, we recommend long-term clopidogrel (Grade 1A). For primary prevention in patients with at least moderate risk for a coronary event, we recommend aspirin, 75 to 162 mg/d, over either no antithrombotic therapy or vitamin K antagonist (VKA) [Grade 2A]; for patients at particularly high risk of events in whom the international normalized ratio (INR) can be monitored without difficulty, we suggest low-dose VKA (target INR, 1.5) [Grade 2A].

The selection of antithrombotic agents in the prevention of recurrent ischemic stroke

The scientific selection of antithrombotic therapy has been dominated by group-based interpretation of data in the form of probability-based statistics in evidence-based medicine. Because the data in large randomized trials are grouped and averaged, the relationship to initial conditions of the patient is lost. There is a pathologic model and basis by which antithrombotic agents may be chosen for prevention of recurrent thrombus and thromboembolism in patients with stroke. This model applies in all settings, but has not been tested when the elements of the model remain connected to the individual patient and his or her unique context. Alternative math models and perception-based science respect the criticality of initial conditions and capture the rules that apply to the actual causal mechanisms within the patient's body. Individualized patient rather than group-based choices insure thrombus-type specific targeted therapy.

Oral anticoagulants in patients with coronary artery disease

Oral anticoagulants have been used in patients with vascular disease for over 40 years, yet their role in the secondary prevention of recurrent cardiovascular (CV) events remains controversial. The objectives of this systematic review are to more reliably determine the role of oral anticoagulants with and without antiplatelet therapy in patients with established coronary artery disease (CAD). Randomized trials in which oral anticoagulants were tested in CAD patients who were treated for at least three months were identified, and each trial was classified by the targeted level of intensity of anticoagulation. Data from the trials were combined using the modified Mantel-Haenszel method, and odds ratios were computed. Data from over 20,000 patients indicated that high-intensity oral anticoagulation (international normalized ratio [INR] >2.8) significantly reduced CV complications and increased bleeding compared with controls. Moderate-intensity oral anticoagulation (INR 2 to 3) also reduced CV complications compared with controls. The combination of moderate-intensity oral anticoagulation and aspirin is more effective and equally as safe as aspirin alone. Low-intensity oral anticoagulation (INR <2) in the presence of aspirin does not reduce CV complications and increases bleeding compared with aspirin alone.

Pre-thrombotic state and impaired fibrinolytic potential in coronary heart disease patients with left ventricular dysfunction

Patients with coronary heart disease (CHD) are at considerable risk for recurrent ischaemic events. A pre-thrombotic state and/or impaired fibrinolysis might play an important role in causing recurrent ischaemic events. Two hundred and fifty-seven CHD patients underwent the dobutamine stress echocardiography test (DSE) to investigate the possible presence of inducible ischaemia; 89 patients showed evidence of stunned and/or necrotic myocardium (resting wall motion abnormalities). Factor VIII activity and fibrinogen levels were significantly higher in patients with stunned/necrotic myocardium than in CHD patients with normal resting wall motions (factor VIII activity, P = 0.004; fibrinogen, P = 0.04). Of interest, after stimulating the fibrinolytic system with the DSE test, plasminogen activator inhibitor-1 activity was significantly higher in patients with necrotic/stunned myocardium than in patients with resting normal wall motion (P = 0.03), whereas tissue-type plasminogen activator activity after the DSE test was significantly lower in patients with stunned/necrotic myocardium than in patients with normal wall motion (P = 0.001). Overall, 30 CHD patients developed induced ischaemia (new wall motion abnormalities) during the DSE test. CHD patients with stunned and/or necrotic myocardium presented decreased fibrinolytic potential and the presence of a hypercoagulable state due to increased factor VIII activity, and fibrinogen levels. Therefore, these CHD patients must be considered at high risk of re-developing coronary thrombosis and might benefit from a more aggressive anticoagulant therapy.

The nature and frequency of potential warfarin drug interactions that increase the risk of bleeding in patients with atrial fibrillation

PURPOSE

To determine the frequency with which atrial fibrillation (AF) patients receiving warfarin are prescribed interacting drugs that could increase bleeding risks.

METHODS

We retrospectively examined medical records for 704 Medicare beneficiaries > or = 65 years of age discharged from Kansas hospitals with AF. We identified all patients receiving warfarin and examined discharge prescriptions for drugs that could increase bleeding risk either by increasing the international normalized ratio (INR) or directly inhibiting hemostasis.

RESULTS

Of 256 patients discharged on warfarin, 138 (54%) were prescribed another medication that could increase bleeding risk. Among these patients, 106 (41%) were discharged with a total of 150 prescriptions for drugs that could interact with warfarin to increase the INR. Antibiotics accounted for 67% of these prescriptions. Fifty-three patients (21%) received 56 prescriptions for drugs which could inhibit hemostasis. These were primarily antiplatelet drugs with 61% of the prescriptions for aspirin. Patients with coronary artery disease were more likely than others to be prescribed warfarin plus antiplatelet agents (OR = 2.80; p = 0.04). More than one interacting drug was prescribed for 20% of the patients.

CONCLUSIONS

AF patients discharged on warfarin were frequently prescribed concomitant medications that increase bleeding risks. These patients should be closely monitored and counseled to watch for signs of bleeding.

Persistence of the prothrombotic state after acute coronary syndromes: implications for treatment

BACKGROUND AND RESULTS

Acute coronary syndromes (unstable angina and acute myocardial infarction) are generally caused by thrombosis over a disrupted atherosclerotic plaque. During the acute phase, antithrombotic therapy (including aspirin and heparin) has been shown to reduce the risk of death or myocardial infarction (MI). The purpose of this review is to examine the high-risk period for clinical thrombotic events that extends for several weeks after presentation and to review the treatments aimed at reducing these events.

RESULTS

More than half of clinical events reported during the first month occur after the first 3 to 5 days that comprise the standard in-hospital treatment period. Several different antithrombotic approaches have been tested, including longer duration of antiplatelet therapy, anticoagulant treatment, and oral glycoprotein (GP) IIb/IIIa inhibitors. Aspirin is effective at reducing risk, and clopidogrel provides additional benefit, as does dalteparin for at least the first month. Warfarin in addition to aspirin, while generally disappointing, has not been adequately tested at higher doses. Oral GP IIb/IIIa inhibitors cause a paradoxic increased risk of death for unclear reasons.

CONCLUSION

Further reduction of risk during the weeks after presentation with acute coronary syndromes remains an important therapeutic goal.

Anticoagulation for acute coronary syndromes and percutaneous coronary intervention in patients with heparin-induced thrombocytopenia

Heparin-induced thrombocytopenia (HIT) is not uncommon in clinical practice, and may go unrecognized in a substantial number of patients. The pathophysiology of HIT has only recently been better understood. Patients with HIT may require anticoagulation for thrombotic complications that result in severe morbidity and mortality. These patients may also require anticoagulation for acute coronary syndromes (ACS), or during percutaneous coronary interventions (PCIs). The direct thrombin inhibitors are currently the anticoagulant of choice in HIT patients with ACS or those undergoing PCI, based on data from several large clinical trials in ACS and PCI populations, and data from smaller experiences, specifically in patients with HIT.

Anticoagulation and the heart

Cardiovascular disease is associated with a heightened risk of thrombosis that can manifest as acute myocardial infarction, cardiac death, and stroke. Similarly, valvular heart disease (which alters blood-flow dynamics) and the insertion of prosthetic materials (which stimulates localized thrombosis on foreign surfaces) are associated with platelet aggregation and thrombin-mediated bioamplification of the coagulation cascade. Physiologic principles and pathobiologic mechanisms determine the preferred means either to prevent or attenuate both thrombosis and subsequent cardiovascular events. Anticoagulant therapy in hospital- and outpatient-based settings has appropriately assumed a central role in the prevention and treatment of thrombotic disorders of the cardiovascular system. Carefully-designed clinical trials will establish safe and effective antithrombotic therapies for wide-scale implementation.

[New diagnostic criteria for myocardial infarction: order in chaos]

An expert committee of the European Society of Cardiology and the American College of Cardiology recently redefined the criteria for the diagnosis of myocardial infarction. The new nomenclature is based on the use of new, biochemical markers of myocardial necrosis (troponin, CK-MB mass) which are more sensitive and specific than those previously used (CK, CK-MB activity). The new criteria adapts to the real possibilities in clinical practice and presents the inconvenient of differing from the established criteria used as epidemiologic, prognostic and therapeutic references. Nonetheless, since there had been different criteria for diagnosing myocardial infarction in the past, the new nomenclature will represent a common way of referring a diagnosis with important practical implications.

Rationale and design of the GRACE (Global Registry of Acute Coronary Events) Project: a multinational registry of patients hospitalized with acute coronary syndromes

BACKGROUND

Acute coronary syndromes (ACS), including the spectrum of conditions from unstable angina to ST segment elevation myocardial infarction, represent a major cause of morbidity and mortality throughout the world. GRACE (the Global Registry of Acute Coronary Events) is a large, prospective, multinational observational study of patients hospitalized with ACS. The aim of GRACE is to improve the quality of care for patients with ACS by describing differences in, and relationships between, patient characteristics, treatment practices, and in-hospital and postdischarge outcomes at hospitals around the world. A goal of this study is to study approximately 10,000 patients with ACS on an annual basis.

METHODS

A total of 18 cluster sites in 14 countries in North America, South America, Europe, Australia, and New Zealand are currently collaborating in GRACE. Clusters were chosen on the basis of local demographic characteristics and hospital facilities to ensure a representative sample of patients with ACS from each country. Patients are identified by use of either active or passive surveillance approaches. A standardized core case report form is completed for all patients. Information on patient demographics, medical history, acute symptoms, clinical characteristics, electrocardiographic findings, treatment approaches, and in-hospital outcomes is collected. Patients are followed up at 6 months after hospital discharge to identify recurrent coronary events, use of various medications, and mortality.

CONCLUSIONS

The information collected from the GRACE project will provide important and extensive insights into patient demographic and clinical characteristics, current practice patterns, and outcomes for patients with ACS from a number of countries throughout the world. Given the pressures of practicing evidence-based medicine, the results of GRACE should provide a multinational perspective into these important outcomes and identify practice variations that will allow new opportunities to improve patient care.

Effects of long-term, moderate-intensity oral anticoagulation in addition to aspirin in unstable angina. The Organization to Assess Strategies for Ischemic Syndromes (OASIS) Investigators

OBJECTIVES

We sought to evaluate whether oral anticoagulant (AC) therapy given for five months was superior to standard (control) therapy in patients with unstable angina receiving aspirin.

BACKGROUND

The long-term risk of myocardial infarction (MI) or death remains high in patients with unstable angina, despite the use of aspirin. Therefore, additional treatments are necessary.

METHODS

Of the 10,141 patients entering the main trial, 3,712 were randomized 12 to 48 h later to receive oral AC therapy (n = 1,848) or standard therapy (n = 1,864).

RESULTS

One-hundred forty patients (7.6%) suffered from cardiovascular death, MI or stroke while receiving oral AC, compared with 155 patients (8.3%) on standard therapy (relative risk [RR] 0.90, 95% confidence interval [CI] 0.72 to 1.14; p = 0.40). The rates of the primary outcomes plus refractory angina were 16.7% (n = 308) versus 17.5% (n = 327) (RR 0.95, 95% CI 0.81 to 1.11; p = 0.53). Countries were divided into good or poor compliers (based on the use of oral AC above or below 70% at 35 days), without knowledge of results by country. In good-complier countries, oral AC was discontinued in only 10.4% of patients at seven days and in 23.6% by five months, compared with 27.6% and 44.9%, respectively, in poor complier countries. There were significant reductions in the risks of both the primary (6.1% vs. 8.9%; RR 0.68, 95% CI 0.48 to 0.95; p = 0.02) and secondary outcomes (11.9% vs. 16.5%; RR 0.70, 95% CI 0.55 to 0.90; p = 0.005) with oral AC in the good-complier countries. There was little difference in the poor-complier countries (9.0% vs. 7.8% for the primary and 21.3% vs. 18.5% for the secondary outcomes, tests for interactions comparing the RRs for the primary and secondary outcomes were p < 0.02 and p = 0.002, respectively, between the two sets of countries). In the overall study, there was an excess of major bleeding (2.7% vs. 1.3%; p = 0.004), which was larger in the good-complier countries (RR 2.71) compared with the poor-complier countries (RR 1.58). There were also reductions in cardiac catheterization (RR 0.80; p = 0.004) and coronary revascularization procedures (RR 0.82; p = 0.06) in the good-complier countries, but not in the poor-complier countries (RR 0.98 and 1.06, respectively, p for interaction of 0.06 and 0.04, respectively).

CONCLUSIONS

Overall, oral AC led to a small, nonsignificant reduction in the risk of the primary and secondary outcomes. Stratifying the countries or centers by their rates of compliance to oral AC suggested that good compliance to oral AC could potentially lead to clinically important reductions in major ischemic cardiovascular events.

Long-term treatment with warfarin in Chinese population

OBJECTIVE

To estimate the incidence of and risks for bleeding and thromboembolic events after warfarin anticoagulation. We also explored the dosage and international normalized ratio (INR) among Chinese patients during long-term warfarin therapy.

METHODS

The population in this retrospective study consisted of inpatients of the only medical center for northern Taipei City, whose initial course of warfarin therapy continued for more than four weeks. Enrollment began in June 1995 and ended in February 1996. Follow-up was completed in March 1998. Relevant data were collected by chart review. The rate of events was calculated using the Kaplan-Meier method, and risk factors were identified by the Cox proportional hazard model.

RESULTS

During the study period, 226 patients were identified. The total follow-up time was 248.7 patient-years. Sixty-one patients (27.0%) received anticoagulation for mechanical prosthetic valve, but their duration of therapy accounted for 48.6% of the total patient-years of follow-up. The starting dosage (mean +/- SD) was 3.4+/-1.4 mg/d (range 1.3-10); the maintenance dosage was 3.1+/-1.2 mg/d (range 1.2-7.7). There were 1060 dosing adjustments and 3398 INR measurements collected for these patients. The independent determinants of maintenance dosage were age, body weight, and indication of mechanical prosthetic valve. The INR was 1.9+/-0.5 (range 1.0-3.7). The cumulative probabilities for hemorrhage at 12, 24, and 34 months were 24.5%, 32.3%, and 38.4%, respectively. The corresponding figures for thromboembolism were 8.5%, 10.7%, and 10.7%, respectively. Three hemorrhages were fatal. After adjusting for other patient characteristics, increasing age was the only independent risk factor identified for bleeding.

CONCLUSIONS

Antithrombotic efficacy seemed to be maintained, although the mean INR was 1.9. Even so, the substantial incidence of bleeding, especially fatal bleeding, remains a concern. Low-intensity anticoagulation might be needed for Chinese patients during long-term warfarin therapy.

Medical treatment for acute coronary syndromes

The medical treatment of acute coronary syndromes with thrombolytic, antithrombin, and antiplatelet agents is a major area of research and a vast topic for clinical review. This review summarizes important recent findings on the background of existing pathological and clinical knowledge to provide an understanding of the basis of current therapy and the new therapies that are likely to be introduced in the near future. Current controversies regarding the management of these conditions and the choice between medical, interventional, and combined strategies in different situations are also discussed.