Prognosis and Management of Atrial in Patients Without Structural Heart Disease

M. DI BIASE,R.TROCCOLI

Atrial fibrillation (AF), the most common sustained cardiac rhythm distur- bance, is increasing in prevalence as the population ages. Although it is often associated with heart disease, AF occurs in many patients with no detectable disease. AF may be related to acute, temporary causes, including alcohol intake (‘holiday heart syndrome’), surgery, electrocution, , , , pulmonary embolism or other pulmonary diseases, and hyperthyroidism or other metabolic disorders. In such cases, successful treatment of the underlying condition may eliminate AF.AF may be associat- ed with another supraventricular , the Wolff-Parkinson-White (WPW) syndrome, or atrioventricular (AV) nodal re-entrant , and treatment of these primary reduces the incidence of recur- rent AF. AF is a common early postoperative complication of cardiac or tho- racic surgery. Specific cardiovascular conditions associated with AF include (most often disease), coronary artery dis- ease, and hypertension, particularly when left is present. In addition, AF may be associated with hypertrophic or dilated car- diomyopathy or with congenital heart disease, especially atrial septal defect in adults. The list of aetiologies also includes restrictive (such as amyloidosis, haemochromatosis, and endomyocardial fibrosis), car- diac tumours, and constrictive pericarditis. Other heart diseases, such as even without mitral regurgitation, calcification of the mitral annulus, cor pulmonale, and idiopathic dilation of the right atrium, have been associated with a high incidence of AF. AF is commonly encoun-

Institute of Cardiology, University of Foggia, Foggia, Italy 118 M.Di Biase,R.Troccoli tered in patients with the sleep apnoea syndrome, but whether the arrhyth- mia is provoked by hypoxia or another biochemical abnormality or mediated by changes in pulmonary dynamics or right atrium factors has not been determined.

AF and Hyperthyroidism

AF occurs in 10–25% of patients with hyperthyroidism, more commonly in men and the elderly than in women or patients less than 75 years old [1, 2]. Treatment is primarily directed toward restoring a euthyroid state, which is usually associated with a spontaneous reversion to sinus rhythm. Anti- arrhythmic drugs and electrical cardioversion are generally unsuccessful while the thyrotoxic condition persists [3, 4]. β-Blockers are somewhat effec- tive in controlling the ventricular rate in this situation, and aggressive treat- ment with intravenous β-blockers is particularly important in cases of thy- roid storm, for which high doses may be required. Calcium channel antago- nists may also be useful [4]. Although specific evidence is lacking in AF caused by hyperthyroidism, oral anticoagulation is recommended to prevent systemic embolism [5].

AF and Pulmonary Diseases

Supraventricular arrhythmias, including AF, are common in patients with chronic obstructive lung disease [6, 7] and have adverse prognostic implica- tions in patients with acute exacerbations of chronic obstructive pulmonary disease [8]. Treatment of the underlying lung disease and correction of hypoxia and acid–base imbalance are of primary importance.

AF and Wolff-Parkinson-White Syndrome

AF may induce and sudden death in patients with the WPW syndrome when atrial impulses are conducted antegrade across a bypass tract. This complication is feared but infrequent. The incidence of sudden death ranges from 0 to 0.6% per year in patients with WPW syn- drome. Radiofrequency ablation of the accessory pathway is usually the pre- ferred therapy for patients with pre-excitation syndromes and AF. Anti- arrhythmic drugs may be useful in selected cases. Digoxin should be avoided because of the risk of paradoxical acceleration of the ventricular rate during AF. β-Blockers do not decrease conduction over accessory pathways during Prognosis and Management of in Patients Without Structural Heart Disease 119 pre-excited periods of AF and could cause hypotension or other complica- tions in patients with tenuous haemodynamics.

AF and Pregnancy

AF is rare during pregnancy [9] and is usually associated with another underlying cause, such as mitral stenosis [10], congenital heart disease [11], or hyperthyroidism [12]. A rapid ventricular response to AF can have serious haemodynamic consequences for both the mother and the fetus. In a preg- nant woman who develops AF, diagnosis and treatment of the underlying condition causing the dysrhythmia is the first priority. The ventricular rate should be controlled with digoxin, a β-blocker, or a calcium channel antago- nist [13–15].

References

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