Readers, this is the first installment of our new “Atrial Fibrillation Update” monthly section! Look for additional articles in upcoming issues of EP Lab Digest. We will be including research articles, case reports, and overviews on topics such as ablation, devices, and pharmacology.

There are only few clinical entities in the field of cardiac electrophysiology that have recently received more attention than atrial fibrillation (AF). The lately forthcoming significance of AF is probably the product of increasing recognition of its medico-social impact, greater understanding of its mechanism and pathophysiology, and the simultaneous advances in mapping and ablation technology. It is also appropriate that the enthusiasm for curing AF is progressing in parallel with the increasing realization of the availability of valid alternative treatments. Thus, it is timely to again review the available management options for AF.

Clearly, like many other disorders in medicine, AF is not a simple, single disease entity. It is important for the clinician to first and foremost determine the setting, potential morbidity, and the quality of life (QoL) impact of AF in the particular patient being treated. The primary morbidity concerns are the risk for stroke and other systemic embolism; perhaps the least recognized concern is the potential for tachycardiomyopathy. Beyond these clinical concerns, AF has for a long time been considered as a benign disorder causing only bothersome symptoms. In most cases, physicians would tell their patients with paroxysmal AF not to be concerned with it and to simply learn to accept it and to tolerate it. In some cases, however, the frequency and symptoms of paroxysmal atrial fibrillation are very disabling and greatly affect the patient’s QoL. In general, these are patients who are otherwise quite healthy and very active, and would object to long-term antiarrhythmic drug therapy, let alone chronic anticoagulation. Many of these patients with “lone” AF now resort to a potentially curative procedure of either focal or linear ablation.

Figure 1A

The typical sheath and catheter positioning for focal ablation of the left upper pulmonary vein ostium (A), compared with positioning of a linear ablation catheter connecting the upper right and left pulmonary vein ostia using microwave energy (B). (Courtesy of MedWaves, Inc., San Diego, California.)

Figure 1B

The typical sheath and catheter positioning for focal ablation of the left upper pulmonary vein ostium (A), compared with positioning of a linear ablation catheter connecting the upper right and left pulmonary vein ostia using microwave energy (B). (Courtesy of MedWaves, Inc., San Diego, California.)

Hence, there appears to be an evolving dichotomy of AF management, with the more traditional approach maintained for the “organic” AF, which affects mainly the elderly and those with underlying structural heart disease, and the curative approach for lone AF. This dichotomy is a natural progression from the realization that it is significantly more difficult to perform a curative procedure for atrial fibrillation in the setting of underlying structural heart disease and in the aging heart as the atrial milieu provides a substrate for perpetuating and maintaining AF. Thus, in such a situation, focal elimination of AF triggers alone would be unlikely to prevent the arrhythmia. For this cohort of patients, a maze or maze-like procedure would be necessary. This form of ablation is more practical during open-chest surgery. Catheter-based technology using a standard radiofrequency (RF) modality is not suitable for this purpose. Newer modalities may be more appropriate for it, such as modified RF or microwave. Using standard RF catheters, focal ablation is the most common approach for catheter-based procedure. As originally described, focal ablation involves pulmonary vein isolation by focal application of RF ablation at sites believed to be the connecting sleeves between the pulmonary vein and the left atrial tissue. Therefore, one would look for “pulmonary vein potentials”; this is accomplished using multipolar mapping catheter, such as the Lasso® catheter (Figure 1A). Linear ablation, on the other hand, requires a catheter with capability of creating long lesions, such as a microwave catheter with a long antenna (Figure 1B).

The various choices of drug, device, and ablative therapies will be discussed in ensuing articles in the “Atrial Fibrillation Update” section of EP Lab Digest this year. There have been significant advances in mapping technology and ablative therapy, both surgically or catheter-based, in this field. The role of device-based therapy remains important to recognize and review. Drug therapy, although considered less attractive by many patients, remains the mainstay in most instances and is of paramount importance for us to fully understand its scope and implications.

Whether one chooses ablative, device-based, or pharmacologic therapy, it would be important to follow the other dichotomy in AF management: rate versus rhythm control. Not too long ago, there was a considerable effort in restoring and maintaining sinus rhythm. It was believed that sinus rhythm would clearly offer an advantage in preventing stroke, providing exercise tolerance and better QoL, and possibly improving survival. Rate control was considered the last option. Difficulty in maintaining sinus rhythm with drug therapy led to studies assessing rate versus rhythm control. Four large trials, the Atrial Fibrillation Follow-up Investigation of Rhythm Management (AFFIRM)¹ trial, the Rate Control versus Electrical cardioversion (RACE)² trial, the Pharmacological Intervention in Atrial Fibrillation (PIAF)³ trial, and the Strategies of Treatment of Atrial Fibrillation (STAF)⁴ trial, have shown no advantage of a rhythm-controlled strategy over a rate-controlled one. In fact, the AFFIRM trial showed a trend toward better survival in the rate control strategy over the rhythm control strategy. While these trials do not address the management of patients with underlying left ventricular dysfunction, they underscore the relative validity of a rate control option. Perhaps its immediate clinical significance is in the avoidance of the approach of maintaining sinus rhythm at all costs, which is difficult to accomplish in patients with persistent AF; such an approach could lead to other drug-related morbidities and even mortality. The AFFIRM trial also underscores the importance of anticoagulation therapy in the management of AF. In addition, it is important to recognize that these studies were not intended to assess patients with lone or other paroxysmal AF.

While on the one hand, we can consider ourselves as being fortunate to have the many options of therapy for AF, it is, on the other hand, important to recognize the validity, limitations, and appropriateness of each form of therapy. In the next few issues of EP Lab Digest, we hope to elucidate to readers more up-to-date knowledge and perspective of the various treatment options, so that as health care providers, we will be able to advise each of our patients with the best therapy.