Contemporary Concepts In Atrial Fibrillation Ablation

US Cardiology 2006;2(1):1-3


Atrial fibrillation (AF) affects approximately two million people in the US. It is a major cause of stroke, adversely impacts quality of life, and is associated with increased mortality.1-4 Treatment with antiarrhythmic drugs and anticoagulation is still considered first-line therapy in patients with symptomatic AF.

Recent randomized trials4,5 have shown that a strategy of rate control and anticoagulation as indicated is comparable with a strategy of rhythm control using antiarrhythmic drugs in treating many patients with AF. In these trials,4,5 mostly elderly patients had well tolerated AF. Restoring sinus rhythm may be of greater benefit in younger patients because doing so may prevent the progressive atrial remodeling that leads to chronic AF.7

These studies only showed that a strategy of rhythm control using antiarrhythmic drugs was comparable with a strategy of rate control without using antiarrhythmic drugs. A limitation of all these trials is that the rhythm control strategy was not efficacious. For example, in one trial,4 only 39% of patients randomized to the antiarrhythmic drug group were in sinus rhythm at the end of the study. Furthermore, in an analysis of one study8 that evaluated predictors of mortality, sinus rhythm was associated with a 47% reduction in risk of death, whereas use of antiarrhythmic drug therapy was associated with a 49% increase in mortality. This suggests that the neutral results in the rate control compared with rhythm control trials might be explained by the fact that offsetting the detrimental effects of antiarrhythmic drug therapy negated the benefits of antiarrhythmic drugs in restoring sinus rhythm. In theory, a therapy that restores and maintains sinus rhythm while avoiding the deleterious effects of automatic atrial defibrillators (AADs) would improve survival. AF catheter ablation would be one such therapy.

In contrast to antiarrhythmic medications, catheter ablation eliminates the triggers of AF. Haissaguerre et al.9 showed that the triggers of AF originate from the pulmonary veins in most patients with AF. Only a minority of patients have extra-pulmonary vein foci as triggers of AF. The pulmonary veins have been shown to play a critical role in both triggering and maintaining AF. The goal of present-day AF ablation (AFA) is to electrically 'disconnect the pulmonary veins from the rest of the atrium by ablating around the origin of the veins.

Currently, there are at least two techniques of AFA purely anatomical approach, guided by non-fluoroscopic navigation systems. In these anatomically guided techniques, radio frequency ablations (RFA) are delivered circumferentially outside the pulmonary vein ostia with a variety of additional ablation lesions.10

However, most techniques target electrical isolation of the entire pulmonary vein musculature from the left atrium as the end-point. This can be guided by either angiography or intracardiac echocardiography. The approach at the Cleveland Clinic Foundation is summarized below.


Conclusion

Catheter-based ablation for AF is recommended for patients who have failed antiarrhythmic medications. In the future, a better understanding of the basic mechanisms of AF, along with the on-going development of devices and perfecting of techniques, will make ablation more reproducible and enticing to more laboratories, in spite of the fact that the best ablation technique is yet to be determined. 


Read the full artlice here: https://www.uscjournal.com/articles/contemporary-concepts-af-ablation


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