Atrial fibrillation is the most common sustained arrhythmia observed clinically. Its prevalence increases from approximately 0.5% in individuals younger than 65 years of age to 10% in indi-viduals older than 80. Diagnosis is usually straightforward by means of an ECG. The ECG may also enable the identification of a prior myocardial infarction, left ventricular hypertrophy, and ven-tricular pre-excitation. Hyperthyroidism is an important treatable cause of atrial fibrillation, and a thyroid panel should be obtained at the time of diagnosis to exclude this possibility. With the clini-cal history and physical examination as a guide, the presence and extent of the underlying heart disease should be evaluated, pref-erably using noninvasive techniques such as echocardiography. Treatment of atrial fibrillation is initiated to relieve patient symptoms and prevent the complications of thromboembolism and tachycardia-induced heart failure, the result of prolonged uncontrolled heart rates. The initial treatment objective is con-trol of the ventricular rate. This is usually achieved by use of a calcium channel-blocking drug alone or in combination with a β-adrenergic blocker. Digoxin may be of value in the presence of heart failure. A second objective is a restoration and maintenance of normal sinus rhythm. Several studies show that rate control (maintenance of ventricular rate in the range of 60–80 bpm) has a better benefit-to-risk outcome than rhythm control (conversion to normal sinus rhythm) in the long-term health of patients with atrial fibrillation. If rhythm control is deemed desirable, sinus rhythm is usually restored by DC cardioversion in the USA. This is also the preferred strategy in an emergency, eg, atrial fibrillation associated with hypotension or angina. For the elective restora-tion of sinus rhythm, a single large oral dose of propefenone or flecainide may be used, provided that safety is initially docu-mented in a monitored setting. Intravenous ibutilide can also restore sinus rhythm promptly. The selection of a drug to maintain normal sinus rhythm depends on the presence and type of underlying heart disease. An example of an algorithm for drug selection is given in Figure 14–11. Antiarrhythmic drugs remain the preferred rhythm control strategy. However, a comparison of initial strategies for the mainte-nance of normal sinus rhythm is currently undergoing clinical trial. The pivotal role of oral anticoagulation in the prevention of stroke is established. Currently guidelines identify patients who are at particular risk and should undergo long-term anticoagulation.
ESC: Heart failure, CAD, valvular heart disease, LVH
ACCF/AHA/HRS: heart failure, CAD, valvular heart disease, LVH
ESC: Includes LVH with preserved LV function
CCS: Including CAD, LVH, and HFpEF disease with LVH AF AF
Dronedarone Dronedarone ESC: Ablation possible Dronedarone Sotalol Amiodarone as first-line therapy Flecainide
Amiodarone Dofetilide CCS: Sotalol when LVEF > 35%
FIGURE 14–11 Selection of rhythm control therapies depends on presence and nature of any underlying heart disease. Patients may be divided into two broad categories: those with and those without underlying heart disease. Patient with heart failure, left ventricular ejection fraction (LVEF) less than 35%, coronary artery disease (CAD), valvular heart disease, and left ventricular hypertrophy (LVH) fall into the first category. The second category includes patients with mild LVH and with heart failure but a preserved ejection fraction (HFpEF). The recommendations are based on the guidelines of the American College of Cardiology Foundation (ACCF), the American Heart Association (AHA), the Heart Rhythm Society (HRS), and the Canadian Cardiology Society (CCS). AF, atrial fibrillation; ESC, European Society of Cardiology; LV, left ventricle.