Ablate all Asymptomatic Pediatric Patients with Wolff-Parkinson-White Syndrome?

Palpitations, syncope and, less commonly, sudden death, are key symptoms of Wolff-Parkinson-White (WPW) syndrome. In this condition, a pathway capable of rapid anterograde conduction increases the risk of malignant arrhythmia. Ablation cures WPW syndrome and eliminates the risk of sudden death.

Arrhythmias rising from this congenital condition may appear at any time from the first hours after birth to late adulthood. Until recently, asymptomatic patients with incidentally discovered WPW on ECG were thought to be at low risk of a life-threatening event (LTE). Recent studies have shown this is not the case in all patients.

“We have learned that a substantial percentage of asymptomatic patients deemed to be at low risk can develop palpitations, and a small portion are at risk for life-threatening arrhythmias. Risk is a moving target that can change over time, and these patients may simply have not lived long enough for symptoms to occur,” says Peter Aziz, MD, Interim Chair of Pediatric Cardiology and Director of the Inherited Arrhythmia Clinic at Cleveland Clinic Children’s.

As a result, pediatric electrophysiologists have reconsidered their approach to the asymptomatic patient with WPW.

Accurate risk-stratification difficult

Typically, screening for risk in WPW has been conducted with noninvasive testing, but when arrhythmias were found in 10% of patients thought to be at low risk, the evaluation process was called into question.

“We now know that noninvasive testing is not reliable, and our ability to risk-stratify is not good,” says Dr. Aziz. “We determined that if WPW persists during a treadmill test, the pathway is robust and conducts electricity in a sinister way. In contrast, when WPW does not persist during exercise, we can only say that the risk is lower. We have learned, though, that this risk is certainly not zero.”

Today, Dr. Aziz and his colleagues consider ablation the primary treatment for young patients with WPW syndrome, including many asymptomatic individuals.

The change in protocol does not apply to older, asymptomatic adults with WPW, however. “In these cases, risk-stratification has occurred during the process of life. If someone has lived to adulthood symptom free, the probability of developing symptoms later in life is unlikely,” he says.

A place for noninvasive testing

Noninvasive testing continues to serve as the hinge point for conversations with families of asymptomatic patients, who are seen after a screening ECG shows WPW.

“When we tell them we have found a problem that could trigger sudden death in their child, it’s understandably hard for them to take in. It often takes hours of discussion to convince them to support an invasive study on their child,” he explains. “Non-invasive testing does provide another data point to be clear.”

“We emphasize that the risk of catheter ablation is lower than the risk of WPW in almost all cases. Therefore, we have to have a good reason NOT to go after these pathways.”

Post-ablation protocol

At Cleveland Clinic Children’s, patients are followed yearly with ECG testing post ablation. The policy has been driven by the need for yearly clearance to participate in sports. “There are no evidenced-based guidelines for following these patients,” says Dr. Aziz.

This includes guidelines on when it is safe for follow-up to stop after a successful ablation is performed.

“If the ablation is performed at age 8, is it reasonable to stop at age 20?” he queries. “There may be consequences to not following these patients.”

To address this issue, Dr. Aziz and pediatric resident Brendan Burke, MD, identified 166 patients in Cleveland Clinic’s EP lab database with at least one post-ablation follow-up who also met other inclusion criteria. The mean age was 14.4 ± 7 years.

Arrhythmias recurred in 10 patients (6%) at a median of 2.41 months: 7 (70%) occurred within 12 months and 3 (30%) occurred after 12 months.

Seventy percent of all recurrences were captured by routine follow-up; 30% were confirmed after the patients experienced palpitations.

“This suggests the need for obligate follow-up post ablation,” says Dr. Aziz. “When we ablate, we cannot say WPW is cured forever, based on the 6% chance of recurrence seen in our study. Having said that, however, ablation boasts excellent acute success rates, low procedural complications and low recurrence risk.”