American Society of Hypertension Self-Assessment GuideTreatment: special conditions: Co-existing heart disease: atrial fibrillation
Introduction
Atrial fibrillation (AF) is the most common sustained rhythm disorder of the heart affecting approximately 6 million Americans.1 AF occurs in 0.4% of the general population, 4% of the hospital population, and in 40% of patients with congestive heart failure (HF).2, 3, 4, 5 A variety of clinical conditions predispose to the development of AF, the most common being hypertension (see Pathophysiology and Mechanisms of AF in this article). AF is a major cause of serious morbidity such as cerebrovascular embolism (‘stroke’), causing a 5–fold increase in the risk of stroke (including over 10% of all strokes in the elderly). More recently, AF has been found to be associated with significantly increased mortality, especially in the setting of HF.2 The incidence of this arrhythmia increases with age, with the result that AF is fast becoming the latest ‘epidemic’ in an aging population. The economic impact of this disease has been estimated at $6.6 billion.
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Clinical Conditions Predisposing to AF
Several clinical conditions are associated with AF, most importantly coronary artery disease, diabetes, hypertension, valvular heart disease, HF, and hypertrophic cardiomyopathy (HCM6; see Figure 1). Most of these conditions lead to the development of structural changes in the atrium, such as atrial enlargement and infiltration or inflammation of the atria. Hypertensive heart disease and coronary heart disease are the most common underlying disorders in patients with AF in developed countries.
Clinical Consequences of AF
Consequences of AF include both debilitating symptoms (the severity of which can vary significantly from patient to patient) and more serious long term sequelae such as stroke and HF.6 Typical symptoms include palpitations, fatigue, lightheadedness, and reduced exercise capacity. Except for embolization, the symptoms associated with new onset AF are primarily due to a rapid ventricular response and/or the hemodynamic consequences of loss of atrioventricular synchrony. Regardless of
Stroke Prophylaxis
Current guidelines recommend long–term anticoagulation in patients with AF and risk factors for thromboembolism.17, 18, 19 Even patients who seem to be in normal sinus rhythm after AF remain at considerable risk for stroke. For this reason, longer–term risk–based anticoagulation should be prescribed even in patients being managed with a rhythm control strategy (eg, anti–arrhythmic drugs or ablation). Stroke risk and the identification of AF patients who may benefit most from antithrombotic
Rate Control
In addition to anticoagulation, the cornerstones of AF therapy are either control of the ventricular rate during AF (rate control) or strategies to convert the patient back to normal sinus rhythm (rhythm control). There appears to be no survival benefit of one strategy over the other.24 Since rhythm control may be difficult to achieve in all patients, rate control strategies continue to be an important aspect of AF therapy today. Generally, beta–blockers and nondihydropyridine calcium channel
Pharmacological Strategies
A number of agents are effective for the maintenance of normal sinus rhythm in patients with AF. American College of Cardiology/American Heart Association/European Society of Cardiology (ACC/AHA/ESC) guidelines describe amiodarone, disopyramide, flecainide, propafenone, and sotalol as agents with proven efficacy for this use.17 However, meta–analysis of data from 44 clinical trials revealed high rates of AF recurrence (55%–67%) with maintenance anti–arrhythmic therapy, and all AF therapies,
Prevention
As with many of today's cardiovascular diseases, prevention is a laudable goal. Available data now suggest that the risk for the development of AF is tightly aligned to the burden of traditional risk factors for heart disease including hypertension, obesity, diabetes, and ischemia. An early rise of B–type natriuretic peptide, within the range of normal, is a reasonable predictor of the likelihood of developing this disease. Early intervention for other forms of cardiovascular diseases,
Summary
AF is a not uncommon co–morbidity in the setting of hypertension. When present, AF contributes to excess cardiovascular morbidity and mortality. The three overarching principles in the evaluation of AF are: (1) understand the etiology of the arrhythmia as it is often the harbinger of important other cardiac diseases; (2) evaluate the risk for stroke and provide appropriate stroke prophylaxis—this is likely the single most important evaluation and intervention that should be done; and (3)
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