Catheter ablation and progression of paroxysmal AF
ANN ARBOR, MICHIGAN. Atrial fibrillation (AF) tends to progress over time from self-converting paroxysmal (intermittent) to persistent (episodes lasting longer than 7 days or requiring cardioversion) to permanent. A recent study showed a progression rate of 8%/year for paroxysmal, lone afibbers. This rate is significant but not in the same league as the progression rate (16%) observed in afibbers with hypertension or heart failure (24%). Class 1C antiarrhythmic drugs (propafenone, flecainide) cut progression rate in half, but their use is unfortunately contraindicated in many AF patients with underlying heart disease. It is generally believed that progression is associated with remodelling, notably enlargement of the left atrium.

A group of electrophysiologists from the University of Michigan now reports that a successful radio frequency (RF) catheter ablation essentially eliminates progression to persistent/permanent AF during a mean follow-up of 2 years. Their study included 504 paroxysmal afibbers who underwent a RF-powered pulmonary vein isolation (PVI) procedure with additional lesions as required to terminate their AF. The average (mean) age of the patients was 58 years, 67% were men, 47% had hypertension, 10% had coronary artery disease, and 11% had diabetes. The average left atrial diameter was 41 mm (4.1 cm). At follow-up 27 months after the initial procedure, 46% of patients were in normal sinus rhythm (NSR) without the use of antiarrhythmic drugs and 9% were in NSR with the aid of antiarrhythmics.

A total of 193 patients (38%) had one or more repeat procedures with an average of 1.5 procedures per patient. After an average follow-up of 22 months following the most recent procedure, 71% of ablatees were in NSR without the use of antiarrhythmics, while 15% were in NSR with the aid of antiarrhythmics. The remaining 14% either continued to experience paroxysmal AF episodes (9.5%), 1.5% had progressed to persistent AF, and 3% had persistent atrial flutter. The progression to persistent AF occurred in 7 of the 56 patients in whom the ablation procedure had been unsuccessful. Thus, the annual incidence of progression to persistent/permanent AF in the entire group was 0.6% - a very favourable rate when compared to the rates obtained with therapy with pharmaceutical drugs. Age, duration of AF, and diabetes were found to be independent risk factors for progression.

The authors conclude that RF catheter ablation is more effective than pharmaceutical therapy in halting the progression of paroxysmal AF.
Jongnarangsin, K, Morady, F, et al. Effect of catheter ablation on progression of paroxysmal atrial fibrillation. Journal of Cardiovascular Electrophysiology, Vol. 23, January 2012, pp. 9-14 .