UPDATE ON CATHETER ABLATION FOR ATRIAL-FIBRILLATION

Atrial fibrillation (AF) is a common arrhythmia that can be treated wi th antiarrhythmic drugs and electrical cardioversion. New therapies su ch as the automatic implantable atrial defibrillator, multisite atrial pacing, and catheter ablation are being studied extensively. Ablation for AF is in its infancy. There are different mechanisms of AF, and, therefore, there can be no single approach to therapy. One question is whether radiofrequency electricity (RF) is the best source of energy for catheter ablation for AF. RF results have been disappointing for t he treatment of ventricular tachycardia, presumably because of the sma ll size of the lesions that are produced. Other sources of energy such as microwave energy, which produces larger and deeper lesions, may be necessary in the future. RF might be modified to produce a larger les ion, perhaps by cooling the ablating electrode so that neighboring myo cardium does not become charred and a higher dose of electricity can b e delivered with greater penetration into deeper layers of myocardium. These efforts at producing larger lesions must be tempered by close a ttention to maintaining a high level of safety. AF usually is not imme diately life threatening, thus a risky therapy will not be acceptable. The procedure should not expose the patient to excessive procedural t ime or an excessive radiation dose. From laboratory and clinical evide nce, it is clear that a catheter ablation cure for some forms of AF wi ll become available in the future, as long as our understanding of the mechanisms of AF continues to increase and ablative techniques contin ue to evolve.