Effectiveness of flutter and SVT ablations

BURLINGTON, VERMONT. A team of researchers from Vermont College of Medicine, Beth Israel Deaconess Medical Center, and Johns Hopkins University School of Medicine has released a study aimed at determining the effectiveness of radiofrequency catheter ablation procedures for typical right atrial flutter (AFL) and atrioventricular node-dependent supraventricular tachycardia (SVT) including accessory pathways. Their meta-analysis included 18 primary studies involving 1323 patients with AFL and 39 primary studies involving 7693 patients with SVT.

During the period 1995 to 2007 the single procedure success rate for AFL was 91.7%. Eight percent of patients went on to have one or more additional ablations, which brought the multiple procedure success rate to 97%. No procedure-related deaths were reported, but 0.5% of patients did experience an adverse event, most commonly atrioventricular block and pericardial effusion. The single procedure success rate was improved from 90.3% in the period 1995 to 1997 to 94.5% in the period 2004 to 2007. In contrast, a study by Dr. Andrea Nataleís group found that, while only 6.4% of AFL patients having undergone RF ablation experienced flutter during a 21-month follow-up, 60% of patients treated with Class 1 (propafenone, flecainide, disopyramide) or Class 3 (amiodarone, sotalol, dofetilide) antiarrhythmics experienced recurrence of flutter. Thus, it is not surprising that the official guidelines for the management of AFL strongly endorse RF ablation over drug therapy.

During the period 1995 to 2007 the single procedure success rate for SVT was 93.2%. In 6.5% of patients repeat ablations were needed bringing the final, multiple procedure success rate to 94.6%. Post-ablation arrhythmias were observed in 5.6% of patients. Procedure-related mortality was 0.03% with 2 deaths occurring among 2267 patients treated for accessory pathways including Wolff-Parkinson-White syndrome. Adverse events were experienced by 2.9% of patients with atrioventricular block and need for pacemaker installation being the most common. The single procedure success rate for atrioventricular node-dependent SVT improved from 92% in the period 1995-1997 to 97.3% in the period 2001-2003. Antiarrhythmics such as flecainide, propafenone, sotalol and dofetilide have been found to reduce frequency of SVT episodes by 70% to 80% compared to placebo. However, only 50% to 60% of patients with SVT were able to remain in sinus rhythm with drug therapy. These findings are reflected in the 2003 guidelines for SVT management, which recommends RF catheter ablation as first-line treatment. NOTE: All the medical doctors participating in this study have financial ties to medical device companies involved in the manufacturing and marketing of ablation catheters.

Spector, P, et al. Meta-analysis of ablation of atrial flutter and supraventricular tachycardia. American Journal of Cardiology, Vol. 104, 2009, pp. 671-77

Editorís comment: This extensive meta-analysis confirms the efficacy and safety of radiofrequency catheter ablations for typical right atrial flutter and supraventricular tachycardias. However, this does not mean that a prospective ablatee should not seek out the best available electrophysiologist to do the procedure in order to ensure maximum chance of success.