Clinical Consequences of Atrial Fibrillation
Cardiovascular
AF is associated with palpitations, impaired exercise tolerance and symptoms from cardiac failure. Clinical deterioration may follow when AF complicates pre-existing cardiac disorders. In terms of cardiovascular events, women with a single electrocardiograph (ECG) recording showing AF have a five-fold increase in risk. The risk is increased two-fold in men with a single ECG of AF. Ten to 40 % of all elderly patients are asymptomatic. 20 Additionally, in patients with either AF or congestive heart failure (HF) alone, development of the second condition as a concomitant disease carries a particularly poor prognosis. For example, in patients with AF, the subsequent development of congestive HF is associated with increased mortality (men: hazard ratio [HR] 2.7; 95 % confidence interval [CI]; women: HR 3.1; 95 % CI, 2.2–4.2).
Stroke
Stroke and thromboembolic disease are considered the most important complications of AF and their occurrence is increased in both paroxysmal and chronic AF. In an analysis of the Framingham study, the impact of cardiovascular disease in 5,070 participants after 34 years of follow-up found that patients with AF had a nearly five-fold increased risk of stroke compared with age-matched individuals with normal sinus rhythm. 23 Indeed, AF is thought to cause as many as one in five of the 700,000 strokes that occur each year in the US; 24 in individuals over the age of 80, AF is linked to nearly one in every three strokes.
A retrospective study examined whether AF was an independent prognostic factor in 3,849 patients with ischaemic stroke. The study found that AF was associated with a poor prognosis in patients with ischaemic stroke, including longer periods of hospitalisation (median 15 versus nine days), an increased risk of in-hospital medical complications (adjusted relative risk = 1.48, 95 % CI, 1.23–1.79) and recurrent stroke (adjusted HR = 1.30, 95 % CI: 0.93–1.82) when compared with patients without AF.
A retrospective study of 1,061 patients with acute ischaemic stroke demonstrated that patients with AF had an increased stroke severity that was independent of advanced age and other stroke risk factors. The degree of disability from acute ischaemic stroke was significantly different in patients with AF versus those without AF in the 65–74 and 75–84 age groups. Patients with AF are also more likely to have both cerebral lesions and diminished functional status compared with patients without AF.
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Mortality
The mortality rate of patients with AF is double that of patients in sinus rhythm and linked to the severity of underlying heart disease. In the Studies of left ventricular dysfunction (SOLVD), mortality was 34 % for those with AF compared with 23 % for patients in sinus rhythm (p<0.001). This difference was attributed to an increased risk of death due to HF rather than to thromboembolism. Indeed, AF has been found to be an independent risk factor for HF 2 and is associated with poor outcomes in patients with chronic HF. Population-based data indicate that subjects with AF have markedly reduced survival compared with subjects without AF, with risk factor-adjusted odds ratios (OR) for death of 1.5 and 1.9 in men and women, respectively. The current treatments used for AF present additional challenges, which may further increase morbidity and mortality, including the potential to cause fatal proarrhythmia by the inappropriate use of antiarrhythmic drugs.
Quality of Life
AF is associated with reduced quality of life (QoL). In the symptomatic patient, the spectrum of symptoms associated with AF range from palpitations and light-headedness to exacerbation of HF and chest pain, all of which negatively affect QoL. Furthermore, in patients with paroxysmal AF (PAF), QoL, as measured by a generic scale Medical Outcomes Study Short Form 36 (SF-36) has been found to be comparable to that of post-myocardial infarction patients and when compared with healthy subjects (n=47) patients with PAF (n=152) had significantly lower health-related QoL scores (p<0.001). Although impact on QoL can be mostly attributed to physical symptoms of AF, QoL is also influenced by patient factors. Even patients with an apparently clinically silent, asymptomatic AF do not have a typical QoL. Moreover, some patients initially deny that they have any symptoms but when the arrhythmia is ultimately treated, subsequently admit that their QoL was severely restricted. Others appear genuinely asymptomatic, with typical activity scores, although their QoL is evidently low. Consequently, relief of symptoms and improving QoL are often primary goals of therapeutic management of rhythm control interventions.
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A recent study has shown that control of symptomatic PAF patients has a positive beneficial impact on QoL. However, there is no gold standard for measuring QoL in AF patients and most questionnaires are cumbersome and time-consuming to complete. To address these limitations, a patient-guided AF-specific QoL questionnaire (Atrial Fibrillation Effect on Quality-of-life [AFEQT]) was recently developed and validated in a large prospective observational study. The 20-item self-administered AFEQT questionnaire assesses the impact of AF on patients QoL and evaluates patients’ perceptions of their symptoms, functional impairment, treatment concerns and satisfaction with
treatment. Thus, this tool may serve as an important QoL outcome measure in different clinical settings including clinical research, survey studies, or clinical practice. A simple, objective bedside measurement, such as the Canadian Cardiovascular Society Severity in AF scale or disease-specific AF QoL measure, may also be useful in determining the impact of symptoms on QoL.
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