Pharmacological Therapy

In considering pharmacological therapy for the management of AF, one must consider that there are several facets to the management of this arrhythmia. The initial consideration is the need for anticoagulation therapy. Following the decision on anticoagulation, ventricular rate control is the next most pressing therapeutic issue, as a fast ventricular response is the most common cause of symptoms. Finally, acute restoration and long-term maintenance of sinus rhythm vs chronic rate control and anticoagulation in the patient who presents with frequent persistent episodes must be addressed. The pattern of the arrhythmia varies significantly between patients, and this should be considered in the acute management of such patients. A general approach to the management of AF is presented in Fig. 1. The patient who presents with frequent paroxysms that spontaneously terminate within 24 h should generally not be referred for electrical or

Managment Acute
Focal ablation, atrial defibrillator Fig. 1. General Approach to Management of AF.

pharmacological cardioversion unless this pattern changes over the long term. In these patients, the more difficult decisions are determining when and whether to start antiarrhythmic therapy vs rate control, and when the episodes are frequent and prolonged enough to warrant initiation of anticoagulation therapy. These decisions should be dictated by the patient's symptomatology and by the presence or absence of clinical and echocardiography risk factors for thromboembolism. In patients with higher thromboembolic risk and with severe symptoms, the option of restoring and maintaining sinus rhythm may, at least initially, be preferred.

Once the episodes become persistent, the patient must be informed of the fact that the window to restore sinus rhythm without concomitant anticoagulation is fairly narrow. If the pattern is one of a few episodes per yr, acute pharmacological or electrical cardioversion, within the first 24-48 h of the onset of arrhythmia, may be the treatment of choice if the patient is very symptomatic. This may be done without concomitant rate-controlling agents and without anticoagulation. In these patients, the anticoagulation issue is a difficult one, as one must consider that patients may have some episodes that are asymptomatic and therefore go unrecognized. If these episodes become "too frequent," one must consider using antiarrhythmic drugs to eliminate or at least to decrease the number of episodes vs treating the patient with rate-controlling agents. In the absence of clinical data, we would recommend continuing anticoagulation in these patients even if a strategy of rhythm control is chosen, as the risk of asymptomatic recurrences is fairly high. The decision of when to consider the episodes "too frequent," however, is a difficult one. It is one that should be made in agreement with the patient's wishes, and by considering the clinical circumstances that may place the patient at a higher risk of complications, such as worsening heart failure, worsening angina, and thromboembolic complications.

If the AF becomes permanent despite attempts at restoration of sinus rhythm with drugs and direct current (DC) cardioversion—external and internal—then antiarrhythmic therapy should be abandoned. Further management should be aimed at controlling symptoms with pharmacological and nonpharmacological means for rate control, and at protecting the patients with clinical and echocardiography risk factors from the risk of thromboembolism.

Historically, because of the theoretical and physiological advantages of maintaining sinus rhythm and because of several experimental animal studies that support the concept of AF spawning AF, most physicians have attempted the restoration of normal sinus rhythm in virtually all patients with a new onset of this arrhythmia. However, the difficulty in maintaining sinus rhythm over the long term and the dangers of antiarrhythmic therapy must be recognized, as well as the absence of data supporting this approach in the asymptomatic patient, or in the one whose symptoms are easily controlled by rate-controlling drugs. Multicenter randomized trials, such as the Atrial Fibrillation Follow-up Investigation of Rhythm Management (AFFIRM) trial (47) and the Pharmacological Intervention in Atrial Fibrillation (PIAF) trial, will hopefully shed some light on the advantages of one management strategy over the other.

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