There is increasing confusion regarding the results and benefits of catheter and surgical ablation for atrial fibrillation (AF). This is because of rapidly evolving techniques and a wide range of opinion regarding its efficacy. Just as the balloon and stent enthusiasts of the 1980s were viewed with some suspicion by many doctors treating coronary atherosclerosis,^w1 the practice of curative ablation of AF has been critically reviewed by cardiologists.^{w2 w3} This article aims to demonstrate why an apparently chaotic heart rhythm is amenable to cure, critically review the currently employed surgical and catheter techniques, and provide some guidelines as to the appropriate referral of patients for these procedures.

PAROXYSMAL, PERSISTENT, AND PERMANENT AF

AF is usually prefixed by a temporal descriptive term such as paroxysmal or chronic which has implications for the most suitable treatment strategy. A consensus on nomenclature has now been achieved¹ in which an AF event is either the first detected or a recurrent episode. Paroxysmal AF describes episodes that terminate spontaneously within seven days. AF is persistent if it lasts longer than seven days or requires cardioversion by any means to restore sinus rhythm. Permanent AF is reserved for when either attempts to cardiovert have failed or not been attempted.

MECHANISMS UNDERLYING AF

The mechanism of AF is not clearly understood. The predominant theory of the 20th century was that chaotic multiple re-entry circuits, following constantly varying lines of conduction block, perpetuate AF (fig 1).^{w4 w5} This concept was challenged, however, by the observation that in some patients without cardiac structural abnormalities, an ECG pattern of AF can be seen even when there is a definite focal source such as a rapidly firing atrial tachycardia emerging from a pulmonary vein (PV).² A single wavefront propagating across the atria is vulnerable to being split and turned by anatomical obstacles and by …