Delirium Cordis: An Arrhythmia at the Intersection of Pediatric and Adult Electrophysiology
Author + information
- aDepartment of Pediatrics, West Virginia University School of Medicine, Morgantown, West Virginia
- bDepartment of Pediatrics and Communicable Diseases, Division of Pediatric Cardiology, University of Michigan Medical School, Ann Arbor, Michigan
- ↵∗Address for correspondence:
Dr. J. Philip Saul, Department of Pediatrics, West Virginia University School of Medicine, PO Box 8059, Morgantown, West Virginia 26506-8059.
Corresponding Author
In 1876, Carl Wilhelm Hermann Nothnagel first described the irregular pulse, now known to be due to atrial fibrillation (AF), as delirium cordis (1). More than 140 years later, AF is the most common significant cardiac arrhythmia and certainly the most widely studied 1 in history. A PubMed search for articles published in 2017 containing “atrial fibrillation” in the title produces 3,296 results. Filtering these results for the terms “pediatric” or “children” in the abstract drops the number to 6, of which only 3 are actual pediatric studies. Despite AF being such a dominant focus of adult arrhythmia management, it is both a rare finding and a rare focus of study in the pediatric arena, particularly in the absence of additional heart disease. Given that, in this issue of JACC: Clinical Electrophysiology, Furst et al. (2) are to be congratulated for their efforts to contribute to the pediatric AF literature through their paper (2).
The paper includes single-center, retrospectively collected data on 62 patients <22 years of age with lone AF who presented to the Cleveland Clinic over an 11-year period from 2004 to 2015. Although a relatively large group of subjects for this topic, and perhaps technically consistent with the author’s claim of being the “largest study on pediatric AF treatment ever,” several studies on pediatric AF treatment do include generally similar subject numbers (3,4).
So what can be learned from this series? Perhaps to best assess that question, we must step back and consider its ability to answer some of the most important and practical questions on pediatric lone AF.
• What is the recurrence risk after a single episode of AF?
• How often is AF associated with a discrete supraventricular tachycardia (SVT) arrhythmia substrate that could be targeted for ablation, and does this eliminate the risk of recurrent AF?
• What is the outcome of AF ablation procedures in this population, and should pediatric AF ablation be performed by pediatric or adult electrophysiologists?
• When is it appropriate to ablate pediatric patients with recurrent AF?
What Is the Recurrence Risk After a Single Episode of AF?
Of the 64 patients, 13 were lost to follow-up. If these 13 are assumed to be free of AF and counted with the 8 others who had no documented recurrences of AF or symptoms, the recurrence risk after the first episode was very high at 66% (41 of 62), higher than the 39% in a prior report (5). Seven of the 8 patients followed without recurrence were treated with daily medication after the first episode; however, no information was provided on the specific medication used, making it possible that low risk options, such as beta-blockade, were used, which rarely control recurrent AF. With recurrent AF in a pediatric patient, one must always question the role of genetic predisposition. In the future, genetic testing may have a more standard utility in pediatric AF (6), but currently, it may only be informative in very specific cases of recurrent AF with a strong family history in the young; and even then unlikely to be impactful on management.
How Often Is AF Seen With Another SVT Substrate and Does Ablation of it Help?
Similar to a prior report, Furst et al. (2) found an approximately 40% likelihood of a discrete SVT substrate in this patient group, with the notable exclusion of Wolff-Parkinson-White patients from the study (4). The association of AF with manifest accessory pathways (Wolff-Parkinson-White) and the prevention of AF with ablation are well known (7); however, whether ablating concealed accessory pathways modifies the risk of recurrent AF is not clear. The documented or suspected recurrence of AF in 3 of the 6 patients (50%) in this study who underwent other SVT substrate targeted ablation shows that this approach is not always successful at preventing future AF. As other authors have suggested, however, when present, these substrates are probably worth addressing because it may successfully prevent AF in some patients.
What Is the Outcome of AF Ablation Procedures in this Population, and Should Pediatric AF Ablation be Performed by Pediatric or Adult Electrophysiologists?
Of the 49 patients with recurrent AF in the Furst et al. (2) study, only 10 underwent AF targeted catheter ablation. AF ablation was technically successful in all 10 patients acutely, but 50% recurred, necessitating 3 redo procedures. Prior reported experience with pediatric AF ablation is limited to a few small case series (3,8), the most significant of which included 9 patients, age 8 to 19 years, for whom rapidly firing atrial foci were the targeted triggers (3). In that study, catheter ablation was successful in 8 patients (89%), with a 22% recurrence rate. Although the Nanthakumar manuscript (3) does not specify who performed the ablations, personal communication from 1 of the authors noted they were all performed by a single experienced adult practitioner.
The 11-year inclusion period in the Furst et al. (2) study may have increased subject numbers, but probably also decreases the practical applicability of the results. The 10 AF ablations were performed by “various electrophysiologists,” from either pediatric or adult specialties, raising the question of whether the high recurrence risk resulted from: 1) adult electrophysiologists experienced in AF ablation but challenged by pediatric-sized patients; 2) pediatric electrophysiologists challenged by the rare AF ablation; or 3) simply an intrinsic complexity of the disease in younger patients. Many adult AF ablation trials include patients as young as 18 years of age. The pathophysiology, natural history, and outcomes on AF in young adult patients are likely to be more similar to the adolescent AF population than the older adult population. With these thoughts in mind, AF in pediatric patients and young adult patients could be an optimal area for collaboration between our age-divided specialties. In fact, it seems eminently reasonable to have the experience and expertise of both adult and pediatric practitioners present for these procedures, particularly in the younger patients.
When Is it Appropriate Perform an AF ablation in a Pediatric Patient?
This may be the most important question to answer. As noted, the evidence for pediatric AF ablation is limited to a few small case series with variable outcomes, and there are no controlled studies of any sort. Alternatively, the data are clear from multiple studies, including that by Furst et al. (2), that there is a small subset of primarily adolescent pediatric patients with no structural heart disease and multiply recurrent AF, whose disease is resistant to medical therapy. Leaving these young patients in permanent AF, or on lifelong class I/III therapy, is clearly not optimal, without even considering the implications of long-term anticoagulation.
Based on the available data and expert opinions, the recent 2016 Pediatric and Congenital Electrophysiology Society/Heart Rhythm Society Expert Consensus Statement on the use of catheter ablation in children recognized the potential need for ablation therapy for pediatric AF, as well as the higher procedural risks compared to “common” SVT ablation (9). Consequently, there are no Class I indications. Elimination of an SVT substrate or targeting ectopic foci from a single pulmonary vein are considered Class IIa, and an AF ablation with complete pulmonary vein isolation is Class IIb. A complete AF ablation for well-controlled or rare episodes of AF is considered class III, also eliminating “patient choice” as an option for mild disease. The patient management and data presented by Furst et al. (2) is fairly consistent with these guidelines; however, inadequate information is provided to know if some of the patients who underwent AF ablation might have been considered Class III by the guidelines.
Conclusions
The paper by Furst et al. (2) is an important but incremental addition to unraveling the appropriate management of pediatric lone AF. It is clear that AF occurs in otherwise healthy adolescents, can be persistent despite medical therapy, and that ablation has a role. As with so many other rare conditions in pediatrics, however, identifying the optimal management of pediatric lone AF will require a multicenter effort, probably beginning with a registry and eventually a clinical trial. Finally, combining efforts with the adult world both for inclusion of still young patients, perhaps age ≤25, and the now deep procedural experience with AF ablation seems like an appropriate path to follow. Fortunately, 1 of the authors, Dr. Aziz, has adopted pediatric lone AF as a clinical research focus and works in an ideal institution to further these goals.
Footnotes
↵∗ Editorials published in JACC: Clinical Electrophysiology reflect the views of the authors and do not necessarily represent the views of JACC: Clinical Electrophysiology or the American College of Cardiology.
Both authors have reported that they have no relationships relevant to the contents of this paper to disclose.
All authors attest they are in compliance with human studies committees and animal welfare regulations of the authors’ institutions and Food and Drug Administration guidelines, including patient consent where appropriate. For more information, visit the JACC: Clinical Electrophysiology author instructions page.
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