Ablazione.org – Terapia delle aritmie

A cura del Dr. Igino Contrafatto M.D. – Cardiac Electrophysiology – Salus Hospital – Reggio Emilia

Ablation in WPW Syndrome

Since it was first introduced for WPW in the pediatric population in 1990, Radiofrequency Ablation (RFA) has offered a potential definitive cure for arrhythmias that could previously be treated only with medications, D.C. ablation, or surgery. RFA is now widely accepted as a therapy for WPW and is frequently considered to be first-line therapy. This is due to high success rates and a low-risk profile. The success rates, risks, and other lifestyle considerations, including the potential cure for a chronic illness, are important issues when deciding whether a particular patient is a candidate for catheter ablation therapy. A thorough understanding of the current state of catheter ablation therapy is critical to the recommendation of this procedure to the family of a pediatric patient with WPW syndrome.

Results with RFA were more recently published (2007) in a combined pediatric and adult population of 508 patients with accessory pathways. Acute success rates were 94.9% across all locations (highest for left free wall, midseptal, and right freewall locations).

Reference
Pediatric Radiofrequency Ablation Registry. Am J Cardiol 2000

Ablation outcomes in the very young child.
SVT due to WPW in infancy can usually be managed medically and tends to become less frequent after the first few months of life. However, there exists a subset of young patients with medically refractory arrhythmias, complex substrates (multiple accessory pathways and/or CHD), and severe symptoms who could potentially benefit from catheter ablation therapy. Studies from the Registry have suggested that the rates of successful ablation are probably similar to that seen in older children, but the rates of adverse events may be higher. However, there were no significant differences between patients  less than or greater than 18 months when analyzing registry data. As experience is still limited and varied, indications for ablation are more conservative in infants and young children, and an asymptomatic WPW ECG pattern is generally not considered to be an indication for risk stratification or ablation.

Risks and complications
Serious adverse events attributed to catheter ablation are AV block, cardiac perforation, coronary artery involvement, and thromboembolic events. Early registry studies reported an overall complication rate of 3.2% using a very inclusive definition of adverse events, which lumped major and minor events. Second- or third-degree AV block occurred in 0.7% and thrombus formation or thromboembolic event occurred in 0.3%. Hematoma at the catheter entry site was the most common complication reported (1.4%). Initially, patient weight of <15 kg was identified as a risk factor for a higher complication rate, but later studies no longer reported a statistically significant higher incidence of complications in smaller patients. Death has been reported as a complication of pediatric RFA due to cardiac perforation, myocardial trauma, coronary or cerebral thromboembolism, and ventricular arrhythmia. The overall incidence reported in the largest cohort (7600 procedures) of pediatric patients by the Registry was 0.22%.

Radiation exposure during fluoroscopy is important to consider when recommending catheter ablation therapy. Fluoroscopy times can be particularly lengthy during technically challenging procedures, such as those involving a right lateral free wall accessory pathway.

Reference
Pediatric Radiofrequency Ablation Registry. Am J Cardiol 2000