Catheter Ablation Urged in Some Children With Asymptomatic WPW


STOCKHOLM — The natural history of asymptomatic Wolff-Parkinson-White syndrome in younger patients is not as benign as previously believed, Dr. Giuseppi Augello said at the annual congress of the European Society of Cardiology.

A subset of these patients with asymptomatic Wolff-Parkinson-White syndrome (WPW) is at high risk for syncope, cardiac arrest, and sudden death at an early age. These patients can be identified through a combination of risk factors that involves invasive electrophysiologic testing. At that point, they ought to undergo prophylactic catheter ablation of accessory pathways to reduce their risk of life-threatening arrhythmias, according to Dr. Augello of San Raffaele University Hospital, Milan.

He presented a prospective observational study in 477 patients with asymptomatic untreated WPW. During 2,070 patient-years of follow-up after baseline electrophysiologic testing, 16.8% experienced a first arrhythmic event. Ventricular fibrillation occurred in 1.3% of the cohort, atrial fibrillation in 3.8%, and supraventricular tachycardia in nearly 12%. Arrhythmic symptoms began at ages 12–25 years; WPW patients who reached the age of 35 years without developing symptoms were very unlikely to do so subsequently.

Cardiac arrest, syncope, or sudden death occurred in 5.5% of patients. Three risk factors independently predicted these events: young age, inducibility of atrioventricular reciprocating tachycardia or atrial fibrillation during electrophysiologic testing, and the presence of multiple accessory pathways.

Of the WPW patients, 23% had all three risk factors and were therefore classified as high risk. There is a compelling argument for prophylactic radiofrequency catheter ablation of accessory pathways in this group, in Dr. Augello's view.

Another 10% of the patients were rated moderate risk, meaning they were young and had inducible arrhythmias but only a single accessory pathway. Arrhythmic events are rare in such patients, and if they occur at all, it is usually later in life.

The remaining two-thirds of patients were categorized as low risk.

The San Raffaele investigators, led by Dr. Carlo Pappone, are widely viewed as world leaders in the field of catheter ablation of arrhythmias. Last year, they published the results of a randomized trial in which prophylactic catheter ablation of accessory pathways in a group of high-risk children aged 5–12 years with asymptomatic WPW was associated with a 5% incidence of arrhythmic events during the first 2 years of follow-up, compared with a 44% incidence among those randomized to no ablation (N. Engl. J. Med. 2004;351:1197–205).

Dr. Augello noted that the risk-stratification strategy he and his colleagues advocate, which is based on routine electrophysiologic testing of all young, asymptomatic WPW patients, is more aggressive than that recommended in current European and American guidelines. But he argued that those guidelines need to be revisited in light of recent evidence of the early lethality of WPW in a subgroup of asymptomatic patients.

He stressed, however, that radiofrequency ablation in children with WPW is not without risk. In the randomized trial, there was a 3% rate of anesthesia-related complications and a 15% incidence of complications related to the ablation procedure, all minor, except for one case of permanent right bundle-branch block. The procedure should thus be performed only by those who are highly experienced.

“We are the referral center for all of Italy for catheter ablation. We do three or four cases per day of ablation in patients with WPW,” Dr. Augello said.

The San Raffaele group's current policy is to routinely do electrophysiologic studies in all asymptomatic WPW patients who are at least 6 years old or 80 cm in height. In younger, smaller patients, the risk of vascular damage related to an ablation procedure is too great, he said.

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