Antithrombotic therapy in heart failure: a randomized comparison of warfarin vs. aspirin (HELAS)

Nine contemporary therapeutic directions in heart failure

The global burden of heart failure has continued to increase dramatically with 26 million people affected and an estimated health expenditure of $31 billion worldwide. Several practice-influencing studies were reported recently, bringing advances along many frontiers in heart failure, particularly heart failure with reduced ejection fraction. In this article, we discuss nine distinct therapeutic areas that were significantly influenced by this scientific progress. These distinct areas include the emergence of sodium-glucose cotransporter-2 inhibitors, broadening the application of angiotensin-neprilysin inhibition, clinical considerations in therapy withdrawal in those patients with heart failure that 'recover' myocardial function, benefits of low-dose direct oral anticoagulants in sinus rhythm, targeted therapy for treating cardiac amyloidosis, usefulness of mitral valve repair in heart failure, the advent of newer left ventricular assist devices for advanced heart failure, the role of ablation in atrial fibrillation in heart failure, and finally the use of wearable defibrillators to address sudden death.

Usefulness of Rivaroxaban for Secondary Prevention of Acute Coronary Syndrome in Patients With History of Congestive Heart Failure (from the ATLAS-ACS-2 TIMI-51 Trial)

Patients with both acute coronary syndromes (ACS) and congestive heart failure are at an increased risk of recurrent cardiovascular (CV) events attributed in part to both excess thrombin generation and impaired fibrinolysis. We hypothesized that patients with the overlap of ACS and CHF would thus derive particular benefit from antithrombotic therapy with rivaroxaban. ATLAS-ACS-2 Thrombolysis in Myocardial Infarction-51 was a double-blind, multicenter, phase 3 clinical trial that randomized patients within 7 days of an ACS event to standard of care plus either rivaroxaban 2.5 mg BID, 5 mg BID, or placebo (n = 15,526). In this post hoc subgroup analysis, subjects with a history of CHF at randomization (n = 1,694) were evaluated. Among subjects with a history of CHF, both rivaroxaban doses reduced the primary composite end point of CV death, myocardial infarction, or stroke (2.5 mg BID vs placebo: hazard ratio [HR] 0.59, 95% confidence interval [CI] (0.42, 0.81), p = 0.001; 5 mg BID vs placebo: HR 0.61, 95% CI (0.44, 0.84), p = 0.002; p interaction = 0.006). Both doses of rivaroxaban reduced CV mortality (rivaroxaban 2.5 mg BID vs placebo: 4.1% vs 9.0%, HR 0.45, 95% CI [0.27, 0.74], p = 0.002; rivaroxaban 5 mg BID vs placebo: 5.8% vs 9.0%, HR 0.62, 95% CI [0.40, 0.96], p = 0.031) as well as all-cause mortality. There was no significant increase in noncoronary artery bypass graft-related Thrombolysis in Myocardial Infarction major bleeding with either dose of rivaroxaban as compared with placebo (rivaroxaban 2.5 mg BID = 0.4% vs rivaroxaban 5 mg BID = 1.1% vs placebo = 0.5%). Rivaroxaban also did not increase either intracranial hemorrhage or fatal bleeding. In conclusion, in ACS subjects with a history of CHF, secondary prevention with rivaroxaban reduced the composite of CV death, myocardial infarction, or stroke without an increase in noncoronary artery bypass graft-related major bleeding. These findings require further prospective evaluation in an adequately powered phase 3 study.

Rationale and design of a randomized, double-blind, event-driven, multicentre study comparing the efficacy and safety of oral rivaroxaban with placebo for reducing the risk of death, myocardial infarction or stroke in subjects with heart failure and significant coronary artery disease following an exacerbation of heart failure: the COMMANDER HF trial

AIMS

Thrombin is a critical element of crosstalk between pathways contributing to worsening of established heart failure (HF). The aim of this study is to explore the efficacy and safety of rivaroxaban 2.5 mg bid compared with placebo (with standard care) after an exacerbation of HF in patients with reduced ejection fraction (HF-rEF) and documented coronary artery disease.

METHODS

This is an international prospective, multicentre, randomized, double-blind, placebo-controlled, event-driven study of approximately 5000 patients for a targeted 984 events. Patients must have a recent symptomatic exacerbation of HF, increased plasma concentrations of natriuretic peptides (B-type natriuretic peptide ≥200 pg/mL or N-terminal pro-B-type natriuretic peptide ≥800 pg/mL), with left ventricular ejection fraction ≤40% and coronary artery disease. Patients requiring anticoagulation for atrial fibrillation or other conditions will be excluded. After an index event (overnight hospitalization, emergency department or observation unit admission, or unscheduled outpatient parenteral treatment for worsening HF), patients will be randomized 1:1 to rivaroxaban or placebo (with standard of care). The primary efficacy outcome event is a composite of all-cause mortality, myocardial infarction or stroke. The principal safety outcome events are the composite of fatal bleeding or bleeding into a critical space with potential permanent disability, bleeding events requiring hospitalization and major bleeding events according to International Society on Thrombosis and Haemostasis bleeding criteria.

CONCLUSION

COMMANDER HF is the first prospective study of a target-specific oral antithrombotic agent in HF. It will provide important information regarding rivaroxaban use following an HF event in an HF-rEF patient population with coronary artery disease.

The Role for Anticoagulation with Warfarin in Patients with Systolic Heart Failure and Normal Sinus Rhythm

Objective:

To evaluate the role of anticoagulation with warfarin in patients with systolic heart failure (HF) and normal sinus rhythm (NSR).

Data Sources:

Literature was accessed through MEDLINE (1950–December 2007) and the American College of Cardiology Annual Scientific Session (2004) using the terms heart failure, warfarin, and anticoagulation.

Study Selection and Data Extraction:

All articles in English identified via the searches were evaluated. We excluded trials that evaluated the use of anticoagulation in patients with atrial fibrillation (AF) or valvular disorders.

Data Synthesis:

Patients with systolic HF are considered to be in a prothrombotic state. Studies have demonstrated a decreased incidence of thromboembolic events with anticoagulation therapy in patients with HF and concomitant AF, valvular dysfunction, or hypercoagulable disorders, but there are limited data supporting the role of anticoagulation in patients with HF and NSR. There are 3 prospective clinical trials and 1 ongoing trial designed to assess the efficacy of warfarin in patients with HF and NSR. These trials compare warfarin with antiplatelet therapy or no antithrombotic therapy. Warfarin did not show a benefit in the primary clinical composite outcome of death, myocardial infarction, or stroke, but was associated with more adverse events. However, these trials were underpowered to detect a difference between treatment arms.

Conclusions:

There is no objective evidence to support the need for anticoagulation with warfarin in patients with systolic HF and NSR. Additional large randomized, controlled trials need to be completed to determine the efficacy and safety of anticoagulation with warfarin in such patients.

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).

The role of aspirin in cardiovascular prevention: implications of aspirin resistance

Aspirin is well recognized as an effective antiplatelet drug for secondary prevention in subjects at high risk of cardiovascular events. However, most patients receiving long-term aspirin therapy still remain at substantial risk of thrombotic events due to insufficient inhibition of platelets, specifically via the thromboxane A2 pathway. Although the exact prevalence is unknown, estimates suggest that between 5.5% and 60% of patients using this drug may exhibit a degree of "aspirin resistance," depending upon the definition used and parameters measured. To date, only a limited number of clinical studies have convincingly investigated the importance of aspirin resistance. Of these, few are of a sufficient scale, well designed, and prospective, with aspirin used at standard doses. Also, most studies do not sufficiently address the issue of noncompliance to aspirin as a frequent, yet easily preventable cause of resistance to this antiplatelet drug. This review article provides a comprehensive overview of aspirin resistance, discussing its definition, prevalence, diagnosis, and therapeutic approaches. Moreover, the clinical implications of aspirin resistance are explored in various cardiovascular disease states, including diabetes mellitus, hypertension, heart failure, and other similar disorders where platelet reactivity is enhanced.

Efficacy of antithrombotic therapy in chronic heart failure: the HELAS study

BACKGROUND

It is not clear if long-term antithrombotic treatment has a beneficial effect on the incidence of thromboembolism in chronic heart failure (CHF). The HELAS study (Heart failure Long-term Antithrombotic Study) is a multicentre, randomised, double-blind, placebo-controlled trial to evaluate antithrombotic treatment in patients with CHF.

METHODS

197HF patients (EF <35%) were enrolled. Patients with Ischaemic Heart Disease were randomised to receive either aspirin 325mg or warfarin. Patients with Dilated Cardiomyopathy (DCM) were randomised to receive either warfarin or placebo.

RESULTS

Analysis of the data from 312 patient years showed an incidence of 2.2 embolic events per 100 patient years, with no significant difference between groups. The incidence of myocardial infarction, hospitalisation, exacerbation of heart failure, death and haemorrhage were not different between the groups. No peripheral or pulmonary emboli were reported. Echocardiographic follow-up for 2years showed an overall increase in left ventricular ejection fraction from 28.2+/-6 to 30.3+/-7 p<0.05, which was most obvious in patients with DCM taking warfarin (EF 26.8+/-5.3 at baseline, 30.7+/-10 at 2 years, p<0.05).

CONCLUSIONS

(1) Overall embolic events are rare in heart failure regardless of treatment. (2) Treatment does not seem to affect outcome.

Antithrombotic therapy for congestive heart failure

Patients with congestive heart failure (CHF) are at increased risk of thromboembolic events. However, there is much debate and uncertainty over the use of antithrombotic therapy in these patients. The evidence for oral anticoagulation is limited, although large randomised trial data are forthcoming. Aspirin may be detrimental for heart failure due to a possible interaction with angiotensin-converting enzyme inhibitors, leading to increased hospitalisations from decompensated heart failure. The objective of this review article is to summarise the available evidence regarding the risk of stroke and thromboembolic events in CHF patients, as well as the effectiveness and risks of antithrombotic therapy in these patients.

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].

Antithrombotic therapy is associated with better survival in patients with severe heart failure and left ventricular systolic dysfunction (EPICAL study)

BACKGROUND

In patients with congestive heart failure (CHF), clinical trials have demonstrated the benefit of a number of drugs on morbidity and mortality. Nevertheless so far, there is no published controlled study of long-term antithrombotic therapy in patients with CHF. The aim of this work was to identify the relationship between cardiovascular drug use, especially antithrombotic therapy, and survival of CHF patients in current clinical practice, using an observational, population-based database.

METHODS

The EPICAL study (Epidémiologie de l'Insuffisance Cardiaque Avancée en Lorraine) has identified prospectively all patients with severe CHF in the community of Lorraine. Inclusion criteria were age 20-80 years in 1994, at least one hospitalisation for cardiac decompensation, NYHA III/IV HF, ventricular ejection fraction < or =30% or cardiothoracic index > or =60% and arterial hypotension or peripheral and/or pulmonary oedema. A total of 417 consecutive patients surviving at hospital discharge were included in the database. The average follow-up period was 5 years. Univariate Cox models were used to test the relationship of baseline biological and clinical factors to survival. Cardiovascular drug prescriptions were tested in a multivariate Cox model adjusted by other known predictive factors.

RESULTS

Duration of disease >1 year, renal failure, serum sodium > or =138 mmol/l, old age, serious comorbidity, previous decompensation, high doses of furosemide and vasodilators use were independently associated with poor prognosis at 1 and 5 years. Oral anticoagulants, aspirin, lipid lowering drugs and beta-blockers use were associated with better survival. There was no interaction between aspirin and angiotensin converting enzyme inhibitor use on survival.

CONCLUSION

Antithrombotic therapy was associated with a better long-term survival in our study population of severe CHF. These results together with other previously published circumstantial evidence urge for a prospective, controlled and randomised trial specifically designed to evaluate optimal oral anticoagulants and aspirin in patients with congestive heart failure.

Interaction between Aspirin and ACE Inhibitors in Patients with Heart Failure

Both aspirin (acetylsalicylic acid) and ACE inhibitors are often used concomitantly, especially in patients with both heart failure and ischaemic heart disease, which is the most common underlying cause of heart failure. The safety of the association has been questioned because both drugs affect a related prostaglandin-mediated pathway. Thanks to their vasodilating properties, prostaglandins play an important role in heart failure where peripheral vasoconstriction occurs. Some of the beneficial effects of ACE inhibitors might be related to reduced degradation of bradykinin that enhances the synthesis of prostaglandins, while aspirin, through inhibiting the enzyme cyclo-oxygenase, inhibits the production of prostaglandins. To date no prospective study has been conducted to investigate the effect of long term aspirin treatment in the postinfarction period allowing the possible impact of the interaction between aspirin and ACE inhibitors upon survival to be confirmed or negated. However, the practitioner needs to know how to optimise the treatment of his or her patients. In order to stimulate arguments for and against the use of aspirin in patients with heart failure receiving ACE inhibitors, we searched MEDLINE from 1960 to 2000 using the key words heart failure, aspirin, and ACE inhibitors for English language articles and conducted a review of the available data. We report on the potential mechanisms of the interaction and the results of experimental studies on haemodynamic parameters. Results of retrospective clinical studies, subgroup analysis that were undertaken to evaluate the overall action upon haemodynamic parameters and survival of the association are summarised. Conflicting conclusions have been reported in the literature. Many explanations can be advanced to try to understand these conflicting conclusions: differences in study design (results of retrospective trials have to be interpreted with caution); differences in the choice of the evaluation parameter (problem of the clinical relevance of haemodynamic parameters); differences in the characteristics of the patient (different underlying cardiopathy, e.g. heart failure, hypertension or ischaemic cardiopathy); and differences in the type and the dosage of each treatment (especially ACE inhibitors and aspirin since an interaction might occur more often with dosage of aspirin greater than 250mg).

Anticoagulation and heart failure

There are no clear data regarding whether to use warfarin, aspirin, or no therapy in patients with left ventricular systolic dysfunction. Aspirin use is widespread in patients with vascular disease but it can decrease renal blood flow in low output states. Warfarin may be used in patients with advancing heart failure due to the perceived risk of in situ thromboembolism. However, we know that ejection fraction and symptom class do not always match and that the regulation of warfarin dosing is more difficult in worsening heart failure. Drug use must be individualized, based on knowledge of underlying heart failure etiology, functional class, drug side effects, and renal function. We await ongoing studies to elucidate the differential effects of these drugs on global outcome as well as on the mechanisms by which they achieve their results.

Anticoagulation for heart failure in sinus rhythm

BACKGROUND

Patients with chronic heart failure (heart failure) are at risk of thromboembolic events, including stroke, pulmonary embolism and peripheral arterial embolism, whilst coronary ischaemic events also contribute to the progression of heart failure. Long-term oral anticoagulation is established in certain groups, including patients with heart failure and atrial fibrillation but there is wide variation in the indications and use of oral anticoagulation in the broader heart failure population.

OBJECTIVES

To determine whether long-term oral anticoagulation reduces total deaths and/or major thromboembolic events in patients with heart failure, when compared to placebo.

SEARCH STRATEGY

Reference lists of papers resulting from this search, electronic database searching (MEDLINE, EMBASE, DARE), and abstracts from national and international cardiovascular meetings were studied to identify unpublished studies. Relevant authors of these studies were contacted to obtain further data.

SELECTION CRITERIA

Randomised controlled trials (RCTs) comparing oral anticoagulants with control or placebo. Non-randomised studies were included as they may help in assessing side-effects. Duration of treatment at least 1 month, adults with heart failure due to any underlying cause. Inclusion decisions were duplicated, disagreement resolved by discussion or a third party.

DATA COLLECTION AND ANALYSIS

Data were collected by two reviewers independently and where appropriate data from RCTs were meta-analysed.

MAIN RESULTS

One recent pilot RCT compared warfarin, aspirin and no antithrombotic therapy, but no definitive data have yet been published. Three small prospective studies of warfarin in heart failure were also identified, but were over 50 years old with methods not considered reliable by modern standards. Anticoagulation was more efficacious than control for the reduction of all cause death (odds ratio 0.64 95% CI 0.45,0.90) and the reduction of cardiovascular events (0.26 95% CI 0.16, 0.43). Four retrospective non-randomised cohort analyses and three small observational studies of oral anticoagulation in heart failure included differing populations of heart failure patients and reported contradictory results.

REVIEWER'S CONCLUSIONS

Evidence from the RCTs and observational studies found a reduction in mortality and cardiovascular events with anticoagulants compared to control. This evidence needs to be interpreted with caution. Although oral anticoagulation is indicated in certain groups of patients with heart failure (eg atrial fibrillation), the data available does not support its routine use in heart failure patients who remain in sinus rhythm. A large randomised trial of warfarin in heart failure patients in sinus rhythm is currently in progress data from which will be useful addition to this story.