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ESSENTIALS OF DIAGNOSIS
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ESSENTIALS OF DIAGNOSIS
Presents as an irregularly irregular heart rhythm on examination and ECG.
Prevention of stroke should be considered in all patients with risk factors for stroke (those with heart failure, hypertension, age 65 or older, diabetes mellitus, prior history of stroke or TIA, or vascular disease).
Heart rate control with beta-blocker or calcium channel blockers generally required. Restoration of sinus rhythm with cardioversion, antiarrhythmic medications, or catheter ablation in symptomatic patients.
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GENERAL CONSIDERATIONS
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Atrial fibrillation is the most common chronic arrhythmia, with an incidence and prevalence that rise with age, so that it affects approximately 9% of individuals over age 65 years. It occurs in rheumatic and other forms of valvular heart disease, dilated cardiomyopathy, ASD, hypertension, and CHD as well as in patients with no apparent cardiac disease; it may be the initial presenting sign in thyrotoxicosis, and this condition should be excluded with the initial episode. Atrial fibrillation often appears in a paroxysmal fashion before becoming the established rhythm. Pericarditis, chest trauma, thoracic or cardiac surgery, thyroid disorders, obstructive sleep apnea, or pulmonary disease (pneumonia, PE) as well as medications (beta-adrenergic agonists, inotropes, bisphosphonates, and certain chemotherapeutics) may cause attacks in patients with normal hearts. Acute alcohol excess and alcohol withdrawal (termed holiday heart) may precipitate atrial fibrillation. For regular, moderate drinkers, abstinence from alcohol reduces recurrences of atrial fibrillation by about 50%.
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Atrial fibrillation, particularly when the ventricular rate is uncontrolled, can lead to LV dysfunction, heart failure, or myocardial ischemia (when underlying CAD is present). Perhaps the most serious consequence of atrial fibrillation is the propensity for thrombus formation due to stasis in the atria (particularly the left atrial appendage) and consequent embolization, most devastatingly to the cerebral circulation. Untreated, the rate of stroke is approximately 5% per year. However, patients with significant obstructive valvular disease, chronic heart failure or LV dysfunction, diabetes mellitus, hypertension, or age over 75 years and those with a history of prior stroke or other embolic events are at substantially higher risk (up to nearly 20% per year in patients with multiple risk factors). A substantial portion of the aging population with hypertension has asymptomatic or “subclinical” atrial fibrillation, which can be detected with monitoring devices and is also associated with increased risk of stroke, particularly if it lasts for 24 hours or longer. It is not clear whether, and for whom, oral anticoagulation should be used for subclinical atrial fibrillation, a question that is being addressed in ongoing clinical trials.
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A. Symptoms and Signs
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Atrial fibrillation itself is rarely life-threatening; however, it can have serious consequences if the ventricular rate is sufficiently rapid to precipitate hypotension, myocardial ischemia, or tachycardia-induced myocardial dysfunction. Moreover, particularly in patients with risk factors, atrial fibrillation is a major preventable cause of stroke. Although some ...