Atrial Fibrillation in the Young: Teasing Out Risk and Treatment Options

Targeting the right substrate may unlock the mystery of unexplained pediatric arrhythmias

The chief findings from a new multicenter study affirm a relatively high rate of recurrence in patients with “lone” atrial fibrillation (AF). They also suggest the utility of ablative therapy targeting non-AF substrate in patients with supraventricular tachycardia (SVT) as a useful strategy in select patients.

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Findings from the study were published in Heart Rhythm.

Defining “lone” AF, or AF in the young

The aim of the study, explains Peter Aziz, MD, Director of Pediatric Electrophysiology at Cleveland Clinic Children’s and the study’s senior author, was to better clarify recurrence and management strategies for what has been referred to as “lone” AF, although the authors use a more apporopriate term,  “AF in the young” (AFY).

The authors define AFY as AF in otherwise healthy children and young adults. These patients are free of structural heart disease, cardiomyopathy, ventricular pre-excitation, history of open-heart surgery, hypertension, or thyroid disease. But the real question is: what predisposes these children to what is generally accepted as an adult arrhythmia?

Reconciling historical practice with modern experience

“Historically, the consensus on managing these patients was to treat the acute event and monitor as needed with the understanding that recurrence was likely fairly low,” he says. “But in my own clinical experience over the years, I have found this wasn’t the case.”

He speculates that tracking recurrence of an already rare condition may become lost in the transition to adult care. Despite available evidence to guide practice in adult populations, pediatric AF is not well-described, particularly when it comes to understanding risk and treatment outcomes.

What we do know

Findings from a large cohort study that Dr. Aziz and colleagues published several years ago in Pediatric Cardiology show that AFY affects approximately 7.5 per 100,000 children. Risk is higher in males, and it increases with age and obesity. Additionally, older children with the condition tend to have higher rates of recurrence.

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Dr. Aziz and his research team also looked at data from a single institution to assess outcomes and found inconclusive data linked to three possible treatment strategies: monitoring (no treatment), daily antiarrhythmic medication and ablation therapy. They published these findings in JACC: Clinical Electrophysiology.

“In that small patient population of about 60 or so patients, we really couldn’t find that one strategy was better than the other, which suggested to us that something was missing.” This led to a large, multicenter collaboration with investigators from 13 congenital heart centers across the U.S. The team looked at 241 individuals age 21 and younger. Within this cohort, 83% were male, and the mean age at the time of onset was 16 years.

Study findings: Recurrence is common – with one exception

The study shows that recurrence was common, documented in 94 patients (39%) during 2.16 + 2.6 years of follow-up through electrocardiography, ambulatory monitoring, or with an implantable loop recorder.

Patients with a first-degree family member with history of AF before the age of 50 were more likely to experience recurrence (P = .013) and in a shorter timeframe (P = .047) as compared to their counterparts without a familial history.

The investigators examined recurrence in the no-treatment, medication and ablation groups, respectively. Overall, there was a negligible difference among all responses, except for the cohort receiving non-AF substrate ablation for SVT.

  • 31% recurrence in those (39/125) who were not treated.
  • 38% recurrence in those (24/63) treated with daily antiarrhythmic medication.
  • 26% recurrence in those undergoing ablation; although, AF recurred significantly less often in patients undergoing ablation of a non-AF substrate (86%) to treat SVT.

Recurrence decreased in SVT cohort

Elaborating on this, Dr. Aziz says, “There are few interventions that perturb the natural history of recurrence of AF. One of those interventions is targeting an existing substrate for an arrhythmia called SVT.”

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“If the patient did not have another substrate, we conclude that the AF occurred spontaneously and the intervention, regardless of modality, may not be effective,” he explains. Based on that data, the physicians surmise that an electrophysiology study may be warranted to evaluate if the patient is a candidate for ablation of a non-AF substrate.

“Even if they aren’t a candidate, this step is still valuable in providing better counsel to patients,” asserts Dr. Aziz.

Substrates: The keyhole into unexplained pediatric arrhythmias?

Dr. Aziz and collaborators at other centers are moving toward clinical application of this treatment strategy in a prospective trial. They also plan to investigate a potential genetic biomarker in AFY patients to better understand disease etiology.

“AF is frequently regarded as an adult disease and, in a lot of ways, that the burden does lay in the adult world. But we know there are pediatric patients who develop AF and who don’t have the same substrates [as adult patients],” he says. “It’s likely that those substrates, at least in some patients, are genetic. Understanding how to identify and target those substrates may be a keyhole into unexplained pediatric arrhythmias.”