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Should Patients Over 70 With Afib Take Baby Aspirin

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Antithrombotic therapy in atrial fibrillation: aspirin is rarely the correct choice

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  1. Ian Due north Sabirane,2,
  2. Gareth D K Matthewstwo,
  3. Christopher L-H Huangii
  1. i Rayne Plant, St. Thomas' Hospital, London, UK
  2. 2 Physiological Laboratory, Academy of Cambridge, Cambridge, Uk
  1. Correspondence to Dr Ian N Sabir, Physiological Laboratory, University of Cambridge, Downing Street, Cambridge CB2 3EG, UK; ins20{at}cam.ac.u.k.

Abstract

Atrial fibrillation, the commonest cardiac arrhythmia, predisposes to thrombus formation and consequently increases gamble of ischaemic stroke. Recent years have seen approval of a number of novel oral anticoagulants. Withal, warfarin and aspirin remain the mainstays of therapy. It is widely appreciated that both these agents increase the likelihood of bleeding: there is a popular conception that this chance is greater with warfarin. In fact, well-managed warfarin therapy (INR ii-iii) has niggling issue on bleeding take a chance and is twice equally effective as aspirin at preventing stroke. Patients with atrial fibrillation and a further risk cistron for stroke (CHA2DS2-VASc >0) should therefore either receive warfarin or a novel oral agent. The residue who are at the very lowest risk of stroke are better not prescribed antithrombotic therapy. For stroke prevention in atrial fibrillation; aspirin is rarely the right choice.

  • Atrial Fibrillation
  • Aspirin
  • Antithrombotic
  • Anticoagulant
  • Warfarin

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  • Atrial Fibrillation
  • Aspirin
  • Antithrombotic
  • Anticoagulant
  • Warfarin

Introduction

Atrial fibrillation (AF) is the almost common cardiac arrhythmia affecting more than 1 in 20 Europeans aged over 55.1 ,2 AF results in turbulent menses within the atria, predisposing to thrombus formation. Patients alive with the constant chance that a fragment of thrombus will dislodge, embolise and occlude a cognitive avenue, causing an ischaemic stroke: AF thus markedly increases stroke risk.iii One might await that restoring sinus rhythm would obviate the stroke risk posed by AF. Surprisingly, nevertheless, a large body of data from the seminal RACE and Affirm trials confirm that it does not, probable reflecting ongoing undetected episodes of arrhythmia.4 ,v Information technology is therefore important to deal with the associated risk of stroke directly. This applies to patients with paroxysmal, as well every bit permanent, AF and also to those with atrial flutter.6 While the majority of big trials take focused on patients with non-valvular AF, this finding appears to be applicative to the broader AF and flutter populations.

While occlusion devices designed to forestall thrombus from breaking off and entering the circulation have been developed and evidence a good degree of efficacy, doubts remain equally to their safety: at present they are just considered for use in patients at very high take chances in whom other approaches are contraindicated.7 ,8 For the majority of patients, the mainstays of therapy to reduce stroke take chances are antithrombotic medications. The impact of these drugs in reducing stroke risk is well established.9–15

There are two wide categories of antithrombotic drugs: antiplatelet agents and anticoagulants. Antiplatelet agents interfere with platelet part thereby reducing the likelihood that they will aggregate into a thrombus. Two main types of antiplatelet drugs take been studied for use in AF: aspirin and thienopyridine drugs such equally clopidogrel. Of these, aspirin interferes with prostaglandin synthesis while the thienopyridines block binding of ADP to the platelet surface. Anticoagulant drugs, on the other hand, interfere with the clotting pour, ultimately reducing the rate of fibrin jell formation. Until recently the only unremarkably used oral anticoagulant was warfarin, which blocks the formation of vitamin Yard-dependent clotting factors. In contempo years, three new oral anticoagulant agents, rivaroxaban, apixaban and dabigatran, which block the final common pathway in jell formation, accept come into the market.

The benefits of antithrombotic drugs as regards stroke prevention must exist balanced against their known association with haemorrhage. While the majority of bleeds in patients on these drugs are minor, a proportion are major and life threatening: the well-nigh worrying form of such bleeding is intracerebral haemorrhage (ICH). Naturally, both the determination to care for and the selection of agent prescribed depend on an assessment of relative benefits and risks. An exaggerated perception of the bleeding risk associated with warfarin has resulted in its widespread underuse. This is effectively illustrated by a contempo report that almost a third of patients with AF and flutter in the Loire Valley region of France are undertreated on the basis of American College of Cardiology/American Heart Clan/European Lodge of Cardiology (ESC) guidelines.16 Consequently, patients who might gain a internet benefit from therapy unnecessarily suffer potentially devastating, and even fatal, strokes.

With the recent publication of the RE-LY,17 ROCKET-AF18 and ARISTOTLE19 trials, attending has understandably focused on the potential benefits of the new oral anticoagulants equally compared with warfarin. These drugs will doubtless come up to grade a useful part of our armoury in the future. When it comes to delivering affect for the majority of patients today, however, there are 2 central problems to tackle. Starting time, one must make an informed determination as to whether or not to prescribe an antithrombotic drug, mindful of the bellboy benefits and risks of therapy. Second, ane must choose between antiplatelet and anticoagulant classes. In well-nigh cases this means a choice between aspirin and warfarin.

Stroke hazard

A number of meta-analyses confirm that warfarin treatment to a target international normalised ratio (INR) of 2.5, and a tolerated therapeutic range (TTR) of 2.0–three.0, reduces stroke risk by around two-thirds among the broad pool of patients with non-valvular AF.6 ,20 ,21 This corresponds to an annual absolute risk reduction in all strokes of effectually 2.7%.22 The reduction in risk of both disabling and non-disabling strokes is similar. Importantly, the results of the BAFTA study ostend that do good is particularly marked in patients aged over 75.23

This said, a number of the studies considered within these meta-analyses accept been the subject area of perhaps justifiable criticism on three cardinal grounds.24 Commencement, patients enrolled in a clinical trial are likely to exist more than regularly followed up than would otherwise accept been expected in a existent world setting. This might be expected to upshot in improved INR command, increasing the proportion of time in the TTR, which likely substantially impacts on outcomes. Second, several studies included within these meta-analyses written report higher absolute stroke risks than are observed in mod exercise, which may mean they overestimate the benefits of anticoagulation.25 Third, only patients for whom optimal choice of antithrombotic therapy is regarded as uncertain would usually exist enrolled in comparing studies. Given previous data on the relatively greater efficacy of warfarin than aspirin in preventing stroke, information technology would take been regarded as unethical to deny patients warfarin therapy when it was clearly indicated. This means the patients selected would accept been at a relatively lower risk of stroke as compared with the patient population as a whole: this was demonstrably the instance in the BAFTA study. A recent retrospective meta-assay of studies conducted in a existent earth setting provides clarity. Warfarin results in a ii-thirds reduction in stroke take chances in patients with at least one boosted risk factor for stroke, such as those identified in the CHADS2 (congestive heart failure, hypertension, age over 75, diabetes, stroke history) scoring arrangement, including the presence of congestive middle failure, hypertension, age over 75 or previous stroke.26

Chiefly, data from the RE-LY, ROCKET-AF and ARISTOTLE trials respectively demonstrate that the new oral anticoagulants dabigatran, rivaroxaban and apixaban offer at least not-inferior stroke protection every bit compared with warfarin.17–nineteen The bear on of the new oral anticoagulant agents on stroke risk, also as points around trial design, are dealt with in detail elsewhere.27

Enthusiasm for the choice of aspirin for stroke prevention in AF is largely driven by the upshot of a single trial, SPAF-i.12 This reported a 42% reduction in overall stroke take chances in patients randomised to aspirin as compared with those receiving placebo. Importantly, even in this written report aspirin did non prevent clinically astringent strokes. Furthermore, responses to aspirin were markedly heterogeneous and treatment appeared significantly less effective in the elderly. A meta-assay of seven trials comparison the efficacy of aspirin and placebo in patients in AF who had additional take chances factors for stroke reached a rather more modest conclusion: treatment with aspirin results in a non-significant 1-fifth relative reduction in stroke risk.21 Interestingly, the magnitude of this relative risk reduction is similar to that seen when aspirin is given to patients with vascular disease: presumably a large proportion of those with AF too have vascular disease.28

Estimations of the efficacy of aspirin as compared with warfarin vary: a meta-analysis of half-dozen prevention trials suggests that it is around half every bit constructive in preventing ischaemic strokes in patients with additional risk factors.6 ,21 A question remains equally to whether aspirin is effective at preventing stroke in patients without additional gamble factors (and then-called solitary AF): private trials tend to include very few such patients. Meta-analyses focusing on this grouping suggest that aspirin again reduces the incidence of stroke in this grouping by around a fifth, though notably the CIs include the potential for harm.20 ,21 The role for aspirin in such patients thus remains unclear.

The question every bit to whether dual antiplatelet therapy with aspirin and a thienopyridine might offer an alternative anticoagulation strategy in at risk patients was comprehensively addressed by the ACTIVE-A and Agile-W trials.29 ,30 In essence, combined treatment with aspirin and clopidogrel provides superior protection confronting stroke as compared with aspirin lonely, just markedly inferior protection equally compared with warfarin. Solely from the point of view of stroke risk, it therefore seems that combined treatment with aspirin and clopidogrel could be considered in patients at loftier take a chance of stroke who are non candidates for warfarin. Unfortunately, such a employ of combination therapy to this end is obviated by the haemorrhage risk that it confers (see later). Finally, while combination treatment with aspirin and depression-dose warfarin (eg, to an INR of one.2–1.five) has previously been discussed, data from SPAF-3 ostend that information technology is associated with a much higher stroke risk than is treatment with full-dose warfarin.31 It should therefore non exist used for stroke prevention in AF.

Thus, there are good data demonstrating antithrombotics reduce stroke adventure in patients with non-valvular AF, with warfarin being significantly more effective that aspirin. This is illustrated in the meta-assay data presented in figure 1A.32 Combination therapy with aspirin and a thienopyridine, or aspirin and low-dose warfarin, provides inferior protection confronting stroke and therefore should not exist used for this indication.

Figure 1

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Figure 1

Impact of antithrombotic drugs on chance of stroke and major bleeding in patients with non-valvular atrial fibrillation. (A) Relative effects of aspirin and warfarin on risk of stroke and major bleeding. Lines indicate 95% CIs. Asterisks bespeak differences which are significant at the 95% confidence level. Adapted from McNamara et al (2004)32. (B) Impact of international normalised ratio on take a chance of stroke and intracranial bleeding. Illustration based on information from Singer et al (2009)24.

Haemorrhage risk

A decade-old meta-assay suggests that warfarin therapy carries a greater take a chance of major bleeding than does treatment with aspirin, with an absolute risk of 2.2 as compared with 1.three events/100 patient years.6 Given the small magnitude of this difference, factors in trial pattern that may have influenced this conclusion require consideration. Based on prescribing behaviour at the time, i would expect that a patient assessed as being at a loftier risk of haemorrhage would be more likely to be treated with no medication than with aspirin, and more than likely to be treated with aspirin than with warfarin. This option bias might consequence in the average haemorrhage chance of a patient in the aspirin group being artificially low. The same argument could exist made of the warfarin group. It is unclear how these factors might accept played off against each other in these older trials.

More recent data from the BAFTA report propose that rates of major haemorrhage in cohorts of elderly patients treated with warfarin or with aspirin are essentially indistinguishable.23 Thus, warfarin therapy resulted in an absolute adventure of 1.4 extracranial bleeds/100 patient years as compared with one.6 events with aspirin. 1 must interpret this striking finding with circumspection for three key reasons, nevertheless.33 Showtime, iv-fifths of patients enrolled in the BAFTA study were already taking warfarin or aspirin and thus had already established a track tape of living safely on therapy. The same would not be true for a new patient for whom a therapy needs to exist chosen. 2nd, the study did non allow combination therapy with warfarin and an antiplatelet amanuensis. In real world clinical exercise some patients will inevitably be on both types of medication. Third, as with other clinical trials, one might look TTR to be greater than it would be in a real world setting. These problems are largely settled by a recently published real world written report based on patient registry data: bleeding risk with well-controlled warfarin therapy was the aforementioned equally that with aspirin.32 ,34 It is thus clear that well-managed warfarin therapy results in piddling, if any, more than haemorrhage that does handling with aspirin, especially amid older patients.23 ,34

It is important to note that, the comparisons highlighted are between low-dose (75–100 mg) aspirin and well-managed warfarin therapy in which the patient has an INR that is within the TTR of 2.0–three.0 for the majority of the time. Haemorrhage adventure is markedly greater in patients who are over-anticoagulated, that is, with an INR of greater than 3.0 (Vocaliser et al 200924) (figure 1B). Stroke hazard is effectively contained of INR at INRs of greater that 2.0: information technology is notable that many strokes among those on warfarin occur in patients in whom the INR is subtherapeutic.22 ,35 Well-executed clinical trials report TTRs in the region of 58%–66% (Agarwal et al 201210). There is a broad consensus that a TTR of at least lx% is both necessary and realistic: indeed, a TTR of less than 60% may entirely negate the benefit of warfarin therapy.28

Of form, it is sensible to recall carefully about each patient'southward individualised haemorrhage risk, both prior to starting handling and then on an ongoing basis. Various risk scoring systems such equally HASBLED (hypertension, abnormal renal or liver function, stroke history, bleeding history, labile INR, elderly, ie, age over 65, drug or alcohol utilise) take been proposed to place patients in whom bleeding run a risk is of particular business concern.36 ,37 It should be noted, still, that the predictive accuracy of these scoring systems is relatively poor (with c-statistics in the range of 0.6).

Every bit regards haemorrhage hazard in patients receiving combination therapies, information from the Agile-A and Agile-W trials clearly show that dual antiplatelet therapy is associated with a similar haemorrhage risk as warfarin.29 ,30 Furthermore, the results of the SPAF-III trial demonstrate that treatment with aspirin and low-dose warfarin is associated with a markedly higher bleeding risk than full-dose warfarin lonely.31 Business organisation over haemorrhage is therefore not a viable reason for choosing such therapies over warfarin.

Finally, it is notable that treatment with the new oral anticoagulant agents appears to be associated with a lower risk of ICH than warfarin.15–17 It should be borne in listen, however, that employ of dabigatran is associated with a small, but statistically significant, increase in risk of myocardial infarction.38

Striking a residuum

The do good of antithrombotic drugs, especially anticoagulants, in stroke prevention is clear. If these drugs were risk-gratis, all patients would be treated. The reality is that a decision to care for requires that the benefits of therapy equally regards reduction in stroke risk must be weighed confronting the elevated chance of bleeding, and especially ICH, they bring. Risk scoring systems which award points based on the presence of particular risk factors are useful for assessing a patient's stroke take chances and thus informing a view on balance of hazard between stroke and bleeding. Of these, the best validated is the CHADS2 scoring system mentioned earlier: almanac stroke gamble increases steeply with score (figure 2).

Figure 2

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Effigy 2

Variation in stroke take chances with CHADS2 score. Bars indicate 95% CIs. Stroke rates are adjusted using a multivariate model to remove the effect of aspirin usage. Note that stroke rates are declining and hence individual values may non reverberate the magnitude of stroke run a risk today. Adapted from Cuff et al (2001).35

Modelling studies have calculated the net clinical benefit of warfarin therapy based on stroke take chances equally assessed using the CHADS2 system. Of these, the most informative has been the ATRIA study.24 Drawing on an extensive information set up obtained in a real earth setting over six years, it computed the difference between the annual rate of strokes prevented by warfarin and the annual rate of ICH due to warfarin. ICH hazard was multiplied past a weighting factor of ane.v, though notably the study's findings remained unchanged when this weighting factor was varied between 1.0 and ii.0. Extracranial haemorrhages, most of which practise not pose a significant danger, were excluded.

ATRIA institute cyberspace harm in patients treated with warfarin with a CHADS2 score of 0, that is, in those without boosted take chances factors for stroke. The benefit of warfarin was equivocal at a CHADS2 score of ane. Warfarin therapy resulted in a statistically significant net clinical do good at CHADS2 scores of 2 or greater, with a marked increase in do good with increasing score. It should be noted that the determination to anticoagulate in this study was made by the treating physicians who presumably concluded that patients were relatively prophylactic candidates for anticoagulation, thus resulting in a potential underestimate of bleeding risk. Furthermore, one-half the control group were on aspirin, meaning that this written report might underestimate the true benefit of warfarin equally regards stroke reduction.

The conclusions of the ATRIA study are supported by those of the more recent Danish National Patient Registry Study.39 This reported a neutral impact or net benefit from warfarin at CHADS2 scores of 1 or greater, and fifty-fifty among patients with a CHADS2 of 0 if 1 boosted run a risk factor included in the new CHA2DS2-VASc scoring arrangement (atherosclerotic vascular affliction, historic period between 65 and 74 or female sex, with additional consideration for age over 75) was nowadays. Notably, there was no category of patients for whom aspirin therapy conferred a net clinical do good.

Questions such as the applicability of these findings in the elderly often arise. It is notable that almost half of the patients enrolled in the ATRIA report were aged over 75. Interestingly, the cyberspace benefit of warfarin increased with patient age, being at a maximum among those aged 85 and over. This finding is consistent with that of the before BAFTA written report, which reported substantial internet do good from warfarin among a cohort with a mean age of 82. In the past, a fearfulness over the potentially increased bleeding risk conferred past frequent falls has been cited every bit a reason to avoid warfarin in older patients. Non only does the ATRIA written report argue against this view but outputs from a separate decision analysis model suggest that an AF patient would need to fall more than than 295 times each year for the adventure of ICH to outweigh potential stroke take a chance reduction by anticoagulation with warfarin.40

The weight of testify indicates that combination therapy with aspirin and low-dose warfarin should not exist used, both because information technology does not offer effective protection against stroke and considering its use is associated with an unacceptably high take a chance of ICH.31 Given that the ACTIVE-A and Agile-W trials demonstrated that dual antiplatelet therapy provides inferior protection against stroke, notwithstanding results in the same bleeding risk every bit warfarin,29 ,xxx a combination of aspirin and a thienopyridine should non exist used for this indication. Patients at a high risk of stroke who cannot take warfarin would likely meliorate be treated with one of the new oral anticoagulant agents. Dual antiplatelet therapy could only be justified among patients at a high adventure of stroke who cannot take whatsoever such anticoagulants for reasons other than bleeding risk. This grouping is so small as to exist virtually non-real. There are therefore substantially no patients in whom antiplatelet therapy might be indicated for stroke prevention.

Conclusions

Among the wide pool of patients with AF, well-managed warfarin is far more effective than aspirin at preventing stroke. This makes physiological sense: warfarin is generally used to preclude thrombus formation in veins, whereas aspirin is used to prevent thrombus formation in arteries. While blood in the left atrial appendage, where stroke-causing thrombi tend to form in AF, is arterial, its haemodynamic characteristics are more in common with those of venous blood. At the same time, well-managed warfarin (with an INR in the TTR of two.0–3.0 at least 60% of the time) increases ICH adventure to a like caste as aspirin. On this ground, the utilise of aspirin for stroke prevention in AF is difficult to justify. In the elderly these assertions non but hold, but are truer even so.

For the individual patient, stroke hazard scoring systems accept an of import place in guiding therapy. In essence, their role is to distinguish between ii groups of patients: the minority who are at a very low stroke risk and the majority who are at a relatively higher risk. In the starting time group, defined by a CHA2DS2-VASc score of nix, the bleeding adventure associated with anticoagulant therapy probably cannot be justified. In the 2nd group, information technology clearly tin can. This is reflected in the preferred therapies suggested in current ESC guidelines,28 an adapted algorithm of which is presented in figure 3. Notably these guidelines recommend the continuation of anticoagulant therapy even following ablation procedures.

Figure 3

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Figure 3

Algorithm for choosing antithrombotic therapy for stroke prevention in patients with not-valvular atrial fibrillation (AF). Recommendations based on 2010 European Society of Cardiology guidelines—see Camm et al (2010).28 * Aspirin may be considered in these patients, every bit well as in those with one risk cistron for stroke, though information technology is not the preferred choice. ** While these guidelines were published prior to the formal approving of the new oral anticoagulant agents for stroke prevention in AF, they still include mention of dabigatran for this indication. *** Or proceed directly to a new oral anticoagulant. INR, international normalised ratio; TIA, transient ischaemic attack.

The guidelines arrange an of import caveat as regards the utilize of warfarin. Its many drug–drug and drug–food interactions, as well as the frequency of monitoring required, will make achieving an adequate TTR an unrealistic challenge in some patients. Furthermore, it may present an undue chance of bleeding in those patients with the very highest bleeding gamble scores (HASBLED score of ≥3). Such patients volition still benefit from anticoagulation: antiplatelet therapy with aspirin is not an appropriate choice in this setting. Given that the new oral anticoagulants announced to nowadays a lower haemorrhage hazard than warfarin, set against at to the lowest degree equivalent protection confronting stroke, i of these agents would seem a sensible side by side choice. While the electric current ESC guidelines for antithrombotic therapy in AF were published prior to the approval of these new agents, they nevertheless include a place for the use of dabigatran.28 Since their publication, dabigatran and rivaroxaban take been approved for stroke prevention in AF in both the USA and Europe.

In the hereafter, the new oral anticoagulant drugs may come to supplant warfarin every bit the first line anticoagulant therapy in patients with AF. Until the current scientific, clinical and health economical arguments surrounding the use of these agents are resolved, even so, warfarin will remain the first option in the majority of patients. In any case, aspirin is rarely the correct choice of antithrombotic therapy for stroke prevention in AF.

Main messages

  • Warfarin is superior to aspirin at preventing stroke in patients with atrial fibrillation.

  • Well-managed warfarin therapy results in a similar chance of major bleeding as treatment with aspirin.

  • While the majority of patients with atrial fibrillation should be anticoagulated, those with no other risk factors for stroke (CHA2DS2-VASc score of nothing) are best not prescribed any such therapy.

  • Every bit compared with warfarin, the new oral anticoagulants have similar impact on stroke risk yet result in a lower bleeding hazard.

  • Aspirin is rarely the right pick of antithrombotic therapy for managing stroke adventure in atrial fibrillation.

Current research questions

  • What is the optimal management for patients with paroxysmal atrial fibrillation?

  • Do the balance of clinical and wellness economic considerations bespeak to a decreasing futurity office for warfarin, and a growing role for the new oral anticoagulant agents?

  • Is there whatever place for aspirin in managing stroke risk in atrial fibrillation?

Cardinal references

  • Camm AJ, Kirchhof P, Lip GYH, et al. Guidelines for the management of atrial fibrillation. Europace 2010;12:1360–420.

  • Mant J, Hobbs FD, Fletcher K, et al. Warfarin versus aspirin for stroke prevention in an elderly customs population with atrial fibrillation (the Birmingham Atrial Fibrillation Treatment of the Aged Report, BAFTA): a randomised controlled trial. The Lancet 2007;370:493–503.

  • Vocaliser DE, Chang Y, Fang MC, et al. The net clinical benefit of warfarin anticoagulation in atrial fibrillation. Ann Intern Med 2009;151:297–305.

  • Friberg L, Rosenqvist M, Lip GYH. Evaluation of risk stratification schemes for ischaemic stroke and haemorrhage in 182 678 patients with atrial fibrillation: the Swedish Atrial Fibrillation cohort report. Eur Heart J 2012;33:1500.

  • Man-Son-Hing M, Nichol Thou, Lau A, et al. Choosing antithrombotic therapy for elderly patients with atrial fibrillation who are at risk for falls. Curvation Intern Med 1999;159:677.

Multiple choice questions

  1. Regarding the new oral anticoagulants:

    1. dabigatran is mentioned in the 2010 European Society of Cardiology guidelines as being potentially useful for stroke prevention in atrial fibrillation (T)

    2. these agents are generally associated with a greater risk of haemorrhage than is well-managed warfarin therapy (F)

    3. they may be used equally first-line agents (T)

    4. dabigatran has been associated with a pocket-sized increase in take chances of myocardial infarction (T)

    5. these agents work by blocking the production of vitamin-G dependent clotting factors (F)

  2. Regarding warfarin:

    1. warfarin therapy can safely be discontinued following an atrial fibrillation ablation procedure (F)

    2. well-managed therapy is reflected by a fourth dimension in therapeutic range (TTR) of greater than lx% (T)

    3. the benefits of warfarin therapy as regards stroke prevention are particularly marked in elderly patients (T)

    4. a patient warfarinised to an international normalised ratio (INR) of 3.0 is at a markedly greater take chances of intracerebral haemorrhage as compared to a patient with an INR of 1.0 (F)

    5. well-managed warfarin therapy is associated with a broadly like bleeding adventure as compared aspirin therapy (T)

  3. Regarding aspirin:

    1. enthusiasm for aspirin use for stroke prevention in atrial fibrillation was driven by the results of a unmarried trial, the results of which have now been superseded (T)

    2. aspirin may be safely combined with low-dose warfarin (F)

    3. aspirin is an antiplatelet drug (T)

    4. combination therapy with aspirin and clopidogrel may be indicated for stroke prevention in some patients with atrial fibrillation (F)

    5. aspirin therapy is useful in patients in whom warfarin cannot exist used (F)

  4. Regarding risk scoring systems used in guiding treatment decisions in patients with atrial fibrillation:

    1. the CHADS2 scoring arrangement awards a point if a patient is aged over 65 (F)

    2. the CHA2DS2-VASc scoring system awards a point for male sex (F)

    3. a patient with a HASBLED score of four is considered to exist at a very high risk of bleeding (T)

    4. the predictive ability of the HASBLED scoring organisation is relatively poor (T)

    5. together a patient's CHA2DS2-VASc and HASBLED scores are sufficient to reach a decision as to which therapy to choose (F)

  5. Given the clinical contexts, the post-obit therapeutic choices are suitable:

    1. a 30 twelvemonth old man with atria fibrillation and no other relevant take a chance factors – no therapy (T)

    2. a 55 yr former woman with hypertension and no contra-indications to warfarin therapy – dabigatran (T)

    3. a 75 year old human being with congestive heart failure, hypertension and a HASBLED score of 4 – warfarin (F)

    4. a 75 year sometime woman with peripheral vascular illness and no contra-indications to warfarin therapy – warfarin (T)

    5. an 80 twelvemonth old woman receiving warfarin therapy with a CHADS2-VASc score of 3 an a time in therapeutic range (TTR) of 65% – warfarin (T)

Acknowledgments

Nosotros thank Dr Victoria Jones for her help in figure preparation. We gratefully acknowledge support from the British Heart Foundation, Wellcome Trust, Medical Enquiry Council, Biotechnology and Biological Sciences Research Quango, Stanley-Elmore Fund, Gonville and Caius College, the Academy of Cambridge'southward Translational Medicine and Therapeutics Programme and the National Institutes for Wellness Enquiry.

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