Atrial Fibrillation in Practice

Gregory Y H Lip

• Publisher: CRC Press
• Year: 2020
• eBook ISBN: 9781000153583
• Edition: 1
• Topic: Medicine
• Subtopic: Audiology & Speech Pathology

This book provides a clear, concise, management-orientated approach to atrial fibrillation. It also provides a useful and practical guide to the issues relating to this common cardiac problem, to improve the care and treatment of these patients.

1. Epidemiology and importance

Introduction

Epidemiology

Incidence and prevalence

Clinical implications and importance

Does asymptomatic atrial fibrillation carry the same degree of risk as the symptomatic form?

Atrial fibrillation in the community

Atrial fibrillation in hospital practice

Atrial fibrillation and the patient

Introduction

Until fairly recently, atrial fibrillation (AF) was often regarded as an innocuous cardiac rhythm disorder, where patients could simply be treated with some digoxin and left well alone. Nothing could be further from the truth – AF is now recognized as a very important cause of mortality and substantial morbidity from heart failure, stroke and thromboembolism. Many patients with AF suffer from reduced exercise capacity as well as poor quality of life.

Indeed, AF is encountered in a wide variety of clinical settings. It may, for example, be discovered incidentally in an asymptomatic patient, it may develop in a patient who merely has a chest infection, fever or it may be found in a patient with a ventricular rate of 200 beats per minute who is too dizzy or lightheaded to stand up! While many are asymptomatic, many patients with AF have a wide variety of cardiorespiratory-presenting symptoms and clinical features, including syncope, heart failure and stroke. Many patients may require long term treatment with potent antiarrhythmic and anticoagulant drugs, which may have important pharmacological interactions and adverse effects.

With the increasing age of the general population, AF is likely to become an even greater public health problem. Current perceptives of AF are summarized below.

Atrial fibrillation – the present

• Recent randomized controlled trials have clearly established the value of antithrombotic therapy in preventing stroke and thromboembolism in AF.

• Clinicians have recognized the limitations of simply treating AF with digoxin.

• Considerable advances have been made in the management of AF as more is understood about the underlying pathophysiology and electrophysiology of this condition.

• Better appreciation of the different clinical subtypes of AF, that is, paroxysmal (recurrent), persistent and permanent AF allows definition of objectives and strategies of management.

Epidemiology

The prevalence of AF varies widely around the world and varies according to the population studied. Much of the clinical epidemiology of AF is also based on data from predominantly Caucasian populations, and information on AF in non-Caucasian populations is scarce. Current perspectives on the epidemiology of AF are summarized below and in Table 1.1.

The risk of AF is well recognized to increase with age and with underlying heart disease. For example, the risk of AF has been found to be associated with increasing age, male sex, heart failure, valve disease, coronary heart disease, diabetes and hypertension. In the Cardiovascular Health Study, 57% of people with AF had clinical cardiovascular disease, and with AF had sub-clinical cardiovascular disease, and a further 35% had sub-clinical cardiovascular disease (being defined as abnormal findings on echocardiography or carotid ultrasound). Conversely, AF is uncommon in infants, children and healthy young adults.

Epidemiology of atrial fibrillation

• AF is the most common sustained cardiac rhythm disorder (Figure 1.1).

• AF is more common with increasing age, and is associated with common cardiovascular and non-cardiovascular diseases.

• Common cardiac causes of AF include hypertension, valve disease and ischaemic heart disease.

• Common non-cardiac causes of AF include thyroid disease, chest disease and intrathoracic pathology.

• Much of the clinical epidemiology of AF pertains to Caucasian populations. In Afro-Caribbeans, hypertension is likely to be the most common cause, while in Indo-Asians, ischaemic heart disease is the most common.

Figure 1.1
Hospitalizations for cardiac arrhythmias. VT – ventricular tachycardia; VF – ventricular fibrillation; SSS – sick sinus syndrome; PSVT – paroxysmal supraventricular tachycardia; AF – atrial fibrillation. Adapted from Bialy et al. J Am Coll Cardiol 1992; 19: 41 A.

Incidence and prevalence

The prevalence of AF approximately doubles with each advancing decade of age, from 0.5% at age 50-59 years to almost 9% at age 80-89 years (see Figure 1.2). AF is also becoming significantly more prevalent, increasing in men aged 65-84 years from 3.2% in 1968-1970 to 9.1% in 1987-1989, an increase which is not explained by an increase in risk factors such as valve disease or myocardial infarction. It is estimated that more than one-half (56%) of people with AF are aged >75.

Table 1.1
Ethnic differences in atrial fibrillation

	White (n=213)	Black (n=10)	Asian (n=22)
Age in years:	75.3 (11.0)	73.1 (12.1)	62.4 (15.5)
mean (SD)
Past medical history
None	19	1	2
Ischaemic heart disease	53(24.9%)	1	10 (45/5%)
Valvular heart disease	11	0	2
Ischaemic and valvular heart disease	5	0	0
Thyroid disease	16 (7.5%)	0	0
Cardiomyopathy	0	0	2
Heart failure	39	3	4
Hypertension	45 (21.1%)	5 (50%)	1
Cerebrovascular disease	29 (13.6%)	0	2
Diabetes mellitus	22	0	2
Other	8	0	2

Applying age-specific prevalence rates to the population structure of England and Wales allows England and Wales specific estimates to be derived. Using this approach, the overall prevalence in England and Wales is 1.1%, rising to 6.1% in people aged >65, and to 8.6% in people aged >75.

AF is more common in men than women and over one-half (56%) of people with AF are aged >75. For example, in the largest UK study from Newcastle, the prevalence was 10% in men and 5.6% in women aged >75. Studies that have sub-divided AF into chronic and paroxysmal suggest that about one-quarter is paroxysmal, with the latter being younger and with a higher proportion (approximately 50%) being ‘lone’ AF.

In the Cardiovascular Health Study, the reported incidence for men aged 65 to 74 and 75 to 84 were 17.6 and 42.7 per 1000 person years respectively and for women, 10.1 and 21.6. Framingham study results were similar, but with smaller differences between men and women. On the basis of 38-year follow-up data from the Framingham Study, men had a 1.5-fold greater risk of developing AF than women after adjustment for age and predisposing conditions.

Clinical implications and importance

Key issues regarding the clinical implications and importance of AF are summarized in the box. The main burden of AF management rests with primary care clinicians as many do not present to hospital. Issues hence relate towards better detection and appropriate investigation of such patients.

Clinical implications and importance of AF

• AF represents a frequent problem not only for hospital physicians but also for primary care physicians.

• Most of AF appears to be managed by general practitioners, and in fact, only a third of patients with AF have ever been admitted to hospital

• Surveys of AF in the community and among ...

Table of contents

• Cover
• Title Page
• Copyright Page
• Dedication
• Contents
• 1 Epidemiology and importance
• 2 Aetiology
• 3 Pathophysiology and electrophysiology
• 4 Clinical features
• 5 Investigations
• 6 Non-drug management
• 7 Drug management
• 8 Management strategies
• 9 Antithrombotic therapy
• Index