Atrial fibrillation and the elderly

Atrial fibrillation (AF) is common in the elderly and symptoms include dyspnoea, palpations, and syncope. Despite the high prevalence of AF in the elderly, its management in general appears far from clear. In this article Dr Martin Fotherby discusses some of the current issues surrounding management of AF in the elderly, including the benefit of screening, prevention strategies and management of embolic risk factors.

Atrial fibrillation (AF) remains the commonest arrhythmia requiring treatment, occurring in approximately five per cent of over 65 year olds and 10 per cent of over 80 year olds¹. To aid discussion of AF, an agreed international classification is now available² (Table 1). However, despite the high prevalence of AF in the elderly its management in general appears far from clear³. This could change in the next few years as the results of ongoing studies, and new guidelines, should lead to significant improvements in AF management. Some issues in AF that need to be addressed are outlined below.

Screening for AF

AF is common in the elderly, and it is associated with serious thrombo-embolic sequelae. However, the risk of this can be reduced by therapy raising the question of whether we should be screening the elderly (>65 years) for AF.

The commonest symptoms associated with AF include dyspnoea, palpitations, chest discomfort and dizziness/syncope. AF also occurs commonly in association with hypertension, diabetes mellitus and he 22422y242w art disease. It would seem sensible to manually check the pulse in patients presenting with these symptoms or conditions. However, many patients may have asymptomatic AF, so it is debatable whether screening is worthwhile, and if so how best to undertake it? These questions are currently being addressed in the ongoing Screening for Atrial Fibrillation in the Elderly study⁴. This will randomise 5,000 patients in primary care to systematic screening and 5,000 to opportunistic screening. AF detection rates in these screened populations can be compared to AF detection rates in 5,000 patients in control general practices.

Prevention of AF

In some populations prone to AF, such as hypertensives and those with left ventricular systolic dysfunction, use of Angiotensin Receptor Blockers (ARBs) and Angiotensin-Converting Enzyme (ACE) inhibitors may lower the
chance of developing new onset AF⁵ . This effect may relate to preventative effects of ACE inhibitors and ARBs on electrical and structural atrial remodelling.

Diagnosis of AF

The finding of an irregular pulse in a patient will hopefully prompt a request for an electrocardiogram (ECG) but how best to interpret this? Computer algorithms do not always accurately interpret AF. In one study up to 35 per cent of ECGs were inaccurately interpreted automatically as AF7. If this is not corrected by the physician inappropriate testing and medication (e.g. anti-arrhythmics and/or anticoagulants) may be initiated. A rapid access arrhythmia clinic will help with diagnosis and the management of the increased referrals that will inevitably be generated by a screening regime8.

Management of AF

Once AF is diagnosed what management strategy should be adopted - rate control (using medication to control ventricular rate between 60-90 beats per/min at rest) or rhythm control (aiming for conversion to sinus rhythm either electrically or pharmacologically)?

Converting patients to sinus rhythm may be the ideal but relapse rates are high (up to 50 per cent in the first year) even with the use of expensive long term anti-arrhythmic drugs, which have significant side effects. A rate control strategy has the advantage of avoiding the cost of the side effects of anti-arrhythmic drugs, but patients may retain any symptoms attributable to the AF.

Several randomised controlled trials in patients with persistent AF suggest little difference between rate control or rhythm control strategies in terms of quality of life, cardiovascular outcomes or mortality^9-11. It should also be remembered that these studies were analysed on 'an intention to treat' basis and there were many crossovers between study arms. Although higher hospital admission rates and drug side effects were noted in the rhythm control strategy groups, in those patients who achieved sinus rhythm, quality
of life improved¹².

In general, patients with long standing asymptomatic AF and those difficult to maintain in sinus rhythm should have rate control, i.e. all those with permanent AF and many with recurrent or persistent AF. Those patients with symptoms, recent onset AF or conditions exacerbated by AF (e.g. heart failure) could have cardioversion attempted. However, anticoagulants or antiplatelet therapy should be continued regardless of the strategy used13.

Drugs used for rhythm control include flecainide, propafenone or sotalol in those with minimal or no overt heart disease and good left ventricular function. Sotalol is particularly indicated in those with coronary artery disease and amiodarone in those with heart failure and AF.

Rate control drugs include verapamil, diltiazem or beta-blockers, all of which are safe to use in patients without heart failure¹⁴. The combination of digoxin and beta-blocker may be superior to either used alone in terms of providing better ventricular rate control and left ventricular function14. In stable heart failure beta-blockers also have a place for AF management15.

Of course if new anti-arrhythmic drugs offer greater efficacy and fewer side-effects, rhythm control may become a more attractive strategy. Recently dronedarone, a derivative of amiodarone, has shown promise in the Euridis and Adonis studies, which were presented at the 26th European Congress of Cardiology 2004. It was found to be effective in preventing recurrences of AF and is well tolerated.

Pill in pocket

An alternative to long term anti-arrhythmia therapy in paroxysmal or recurrent AF, particularly if symptomatic, is a single oral dose of anti-arrhythmic at the start of palpitations. For patients without significant heart disease, flecainide or propafenone can terminate up to 90 per cent of arrhythmic episodes¹⁶. This is associated with a low incidence of side effects and hospitalisations with the potential to reduce costs.

Risk stratification

The next major issue in AF management is to address whether the patient requires thrombo-prophylaxis and if so with aspirin or warfarin? This applies whether the patients have paroxysmal, persistent or permanent AF, or whether on a rate or rhythm control strategy. Warfarin is significantly more effective in reducing stroke risk (by approximately two thirds) than aspirin (by approximately one fifth). But because of the greater risk of major haemorrhage with warfarin compared to aspirin, there should be a sufficient high embolic risk to outweigh the co-morbidity drawbacks before prescribing warfarin.

Deciding on the risks and benefits of anti-coagulation for an individual patient is not easy. The risk of stroke increases with age as does the risk of severe bleeds (including cerebral bleeds) with warfarin therapy. If the risk of severe bleeds with warfarin increases from one per cent at age 60 years to approximately three per cent at age 80 years, treatment would only be instituted at stroke risks considerably higher than these. Of course
this does not take into account other risks or concerns that patients have with warfarin therapy or their co-morbidities.

When the stroke risk is high¹⁷ such as over eight per cent per annum (e.g. in patients with previous stroke/TIA or aged over 75 years with several risk factors), or if the risk is low at about one per cent per annum (e.g. in patients under 65 years with no significant risk factors) the advice with respect to warfarin is more easily given. It is in the large number of subjects with stroke risk levels between these extremes when individual advice is more difficult to give.

Clear guidance in this area is required, perhaps along the lines given in the tables published by Thomson et al18. These are tables that combine risk factors to determine whether benefit from warfarin is likely, unlikely or borderline. However, it should be remembered that patients' risks will change with time and reassessments will need to be undertaken annually. In those patients in whom anti-platelet therapy is being considered aspirin can be given at a dose of 300mg daily and if intolerant of aspirin, clopidogrel 75mg can be substituted. Whether the combination of clopidogrel with aspirin is as efficacious as warfarin in patients with AF is as yet unclear¹⁹.

Management of embolic risk factors in AF

It shouldn't be forgotten that the stroke risk in patients with AF can be further reduced by appropriate management of other risk factors e.g. high blood pressure. Even in this high stroke risk group there is evidence that blood pressure remains poorly controlled (>150/90mmHg) in over 25 per cent of patients with AF20. Risks of cerebral haemorrhage in those on warfarin or aspirin increase with higher blood pressures. Prior to starting aspirin or warfarin, patients should have their high blood pressures brought under control (i.e. <150/90mmHg). Management of hyperlipidaemia, heart failure and diabetes should also be optimised.

Conclusion

Production of practical and comprehensive guidelines for management of patients with AF for use in primary and secondary care should help to improve on the current management of AF. The National Institute for Health and Clinical Excellence guidelines for managing AF are due to be published in 2006.

Dr Martin Fotherby is a Senior Lecturer in Ageing and Stroke Medicine at the University of Leicester and a Honorary Consultant Physician at the Glenfield Hospital, Leicester

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References

Go AS, Hylek EM, Phillips KA, et al. Prevalence of diagnosed atrial fibrillation in adults: national implications for rhythm management and stroke prevention: the AnTicoagulation and Risk Factors in Atrial Fibrillation (ATRIA) study. JAMA 2001; 285: 2370-5

Lévy S, Camm AJ, Saksena S, et al. International consensus on nomenclature and classification of atrial fibrillation: A collaborative project of the working group of cardiac pacing of the European Society of Cardiology and the North American Society of Pacing and Electrophysiology. Journal of Cardiovascular Electrophysiology 2003; 14: 443-45

Ho SF, O'Mahony MS, Steward JA, et al. Left ventricular systolic dysfunction and atrial fibrillation in older people in the community - a need for screening? Age and Ageing 2004; 33: 488-92

Swancutt D, Hobbs R, Fitzmaurice D, et al. A randomised controlled trial and cost effectiveness study of systematic screening (targeted and total population screening) versus routine practice for the detection of atrial fibrillation in the over 65s. BMC Cardiovasc Discord 2004; 4(1): 12

Wachell K, Lehto M, Gerdts E, et al. Angiotensin II receptor blockade reduces new-onset atrial fibrillation and subsequent stroke compared to atenolol: the Losartan Intervention For End Point Reduction in Hypertension (LIFE) study. J Am Coll Cardiol 2005; 45(5): 712-9

Vermes E, Tardif JC, Bourassa MG, et al. Enalapril decreases the incidence of atrial fibrillation in patients with Left Ventricular Dysfunction: insight from the Studies Of Left Ventricular Dysfunction (SOLVD) trials. Circulation 2003; 107(23): 2926-31

Bogun F, Anh D, Kalahasty G, et al. Misdiagnosis of atrial fibrillation and its clinical consequences. American Journal Med 2004; 117(9): 636-42

Martins JL, Fox KF, Wood DA, et al. Rapid access arrhythmia clinic for the diagnosis and management of new arrhythmias presenting in the community: a prospective, descriptive study. Heart 2004; 90(8): 877-81

Hohnloser SH, Kuck K-H, Lilenthal J. Rhythm or rate control in atrial fibrillation - Pharmacological Intervention in Atrial Fibrillation (PIAF): a randomised trial. Lancet 2000;

Van Gelder IC, Hagens VE, Bosker HA, et al. A comparison of rate control and rhythm control in patients with recurrent persistent atrial fibrillation. N Engl J Med 2002; 347: 1834-40

Wyse DG, Waldo AL, DiMarco JP, et al. A comparison of rate control and rhythm control in patients with atrial fibrillation. N Engl J Med 2002; 347: 1825-33

Hagens VE, Ranchor AV, Van Sonderen E, et al. Effects of rate or rhythm control on quality of life in persistent atrial fibrillation: results from the Rate Control versus Electrical Cardioversion (RACE) study. J Am Coll Cardiol 2004; 43: 241-7

Page RL. Newly Diagnosed Atrial Fibrillation. N Engl J Med 2004; 351: 2408-16

Taneja S, Lip GYH, Flather M. Recent developments in atrial fibrillation. BMJ 2005; 330: 238-43

Khand AU, Rankin AC, Martin W, et al. Carvedilol alone or in combination with digoxin for the management of atrial fibrillation in patients with heart failure? JACC 2003; 42: 1944-51

Alboni P, Botto GL, Baldi N, et al. Outpatient treatment of recent onset atrial fibrillation with the 'pill-in-the-pocket' approach. N Engl J Med 2004; 351: 2384-91

Lip GYH, Hart RG, Conway. ABC of anti-thrombotic therapy: anti-thrombotic therapy for atrial fibrillation. BMJ 2002; 325: 1022-25

Thomson R, Parkin D, Eccles M, et al. Decision analysis and guidelines for anticoagulant therapy to prevent stroke in patients with atrial fibrillation. Lancet, 2000; 355: 956-62

Lorenzoni R, Lazzerini G, Cocci F, et al. Short-term prevention of thromboembolic complications in patients with atrial fibrillation with aspirin plus clopidogrel: the Clopidogrel-Aspirin Atrial Fibrillation (CLAAF) pilot study. Am Heart J. 2004; 148(1): e6

de Lusignan S, Van Vlymen J, Hague N, et al. Preventing stroke in people with atrial fibrillation: a cross-sectional study. J Public Health 2005; 27(1): 85-92