ROME, ITALY. In 1998 Profs. Haissaguerre and Jais at Hopital Cardiologique du Haut Leveque in Bordeaux discovered that the most common sites of ectopic beats triggering atrial fibrillation (AF) are situated in the pulmonary veins. Since then, electrical isolation of the pulmonary veins from the left atrium has become a standard procedure for eliminating AF through catheter ablation. Now a group of Italian electrophysiologists suggests that some less complex supraventricular tachycardias (SVTs) may act as triggers for AF and that their elimination can prevent recurrence of AF, especially in younger patients with paroxysmal AF and no underlying heart disease (lone afibbers).

Their study involved 257 patients (average age of 53 years, 72% male) who had suffered from drug-resistant symptomatic AF for an average of 3.2 years. Seventy-nine patients (30.7%) had paroxysmal AF, 87 patients (34%) had both paroxysmal and persistent AF, and the remainder had persistent AF. It is interesting that 70 patients started out with paroxysmal AF which converted to persistent after an average of 18 months.

All study participants underwent an electrophysiological study during which an attempt was made to induce SVTs other than AF and flutter. The EPs specifically looked for signs of AF triggering by atrioventricular nodal re-entrant tachycardia (AVNRT), atrioventricular re-entrant tachycardia (AVRT) through an accessory pathway, and focal atrial ectopic tachycardia (FAT). Twenty-six patients had inducible SVT (12 AVNRT, 9 AVRT, and 5 FAT). These specific SVTs were successfully ablated in all 26 patients with no further ablations and no complications. The average procedure time was only 78 minutes with fluoroscopy time averaging 16 minutes. No recurrences of the ablated SVTs were observed during a 21-month follow-up, but 2 patients (7.7%) did experience AF recurrence during follow-up.

Patients with inducible SVT were younger than those in which SVT could not be induced (average age 43 years vs 57 years), were much less likely to have heart disease (23% vs 87%), were more likely to have paroxysmal AF (85% vs 25%), and had smaller left atrial diameters (37 mm vs 44 mm). The researchers conclude that a small (about 10%), but important group of afibbers referred for catheter ablation of AF may have inducible SVTs, the successful ablation of which results in an AF-free future in 92% of cases without the use of antiarrhythmic drugs.

Sciarra, L, et al. How many atrial fibrillation ablation candidates have an underlying supraventricular tachycardia previously unknown? Europace, Vol. 12, 2010, pp. 1707-12

Editor's comment: The finding that AF episodes in a significant proportion of young, lone afibbers with paroxysmal AF may be triggered by previously unknown SVTs is clearly important. Ablation of these less complex arrhythmias is likely to be successful and involves much shorter procedure and fluoroscopy times as well as a very low risk of complications. The observation that 92% of patients with ablated inducible SVT experienced no AF recurrence during a follow-up of 21 months is very encouraging indeed and clearly shows the advantage of an ablation approach "tailored" to the individual patient.