Internal Atrial Defibrillation: What Are the Effects on Mechanical Function?

Abstract

Atrial fibrillation (AF) represents the most common sustained arrhythmia that occurs in 0.3%–6% of the adult population and increasingly with age, and is therefore considered a large burden to the health care system because of direct and indirect costs due to morbidity and mortality rate [1–3]. The principal consequence of AF is the loss of organized atrial contractions that may have important hemodynamic effects on cardiac output expecially in those patients with underlying heart disease in whom the risk of stroke has increased five-fold [4]. Established methods for converting AF to sinus rhythm include treatment with antiarrhythmic drugs and application of external high energy shocks. Success rates ranging from 40% to 70% have been described with antiarrhythmic therapy [5]. The reported success rate for external cardioversion ranges from 61% to 90% [6, 7]. On the other hand, it is well known that electrical cardioversion may be complicated by cerebral, systemic and pulmonary embolic events in 0.6%–7% of patients undergoing the procedure [8, 9]. Thromboembolism after cardioversion has been attributed to the dislodgement of preformed thrombus from the left atrium with the resumption of sinus rhythm and atrial contraction [9, 10]. In the attempt to further reduce the prevalence of thromboembolic complications after electrical cardioversion, transesophageal echocardiography (TEE) has been proposed as a method of screening patients for left atrial thrombus before the external cardioversion. This tool has showed higher values of sensitivity and accuracy in comparison with transthoracic echocardiography (TTE) in this specific field [11, 12].