Author + information
- Michael J. Silka, MD∗ ( and )
- Yaniv Bar-Cohen, MD
- Division of Cardiology, Children’s Hospital Los Angeles, Keck School of Medicine, University of Southern California, Los Angeles, California
- ↵∗Address for correspondence:
Dr. Michael J. Silka, Division of Cardiology, Children’s Hospital Los Angeles, Keck School of Medicine, University of Southern California, 4650 Sunset Boulevard, MS #34, Los Angeles, California 90027.
- cohort studies
- congenital heart defects
- intra-atrial re-entrant tachycardia
The Cambridge University Press dictionary defines a sequel as a book, film, or play that continues the story of a previous work (1). The common approach is for the events of the second version to contain elements of the original work, with the sequel often based on lingering questions or uncertainties. At times, a sequel may lead to a series, in which key elements appear repeatedly.
By analogy, medical diagnoses and conditions may evolve over time, with new or secondary diagnoses resulting because of a primary problem that was ostensibly “cured,” but perhaps with lingering questions and uncertainties. This analogy may be particularly applicable to patients with congenital heart disease (CHD), where late cardiovascular problems may develop decades after surgery.
The study by Labombarda et al. (2) in this issue of the Journal, discusses the increasing prevalence of atrial fibrillation (AF) and permanent atrial arrhythmias in CHD. The study provides some useful insights and, perhaps more importantly, raises further questions about the next sequel or possibly series of events as these patients survive into and beyond middle age.
This multicenter, retrospective cohort study describes patients with CHD that presented with either a new-onset sustained atrial tachycardia or AF. The data were collected from 12 centers with a mean population age of 32 ± 18 years at the time of the first documented atrial arrhythmia. This study offers an epidemiological perspective on the overall types and frequency of atrial arrhythmias in a “young” adult population with CHD and subsequent surgical interventions. Furthermore, it provides longitudinal follow-up of these patients and provides insight into the propensity for these patients to develop AF or other persistent forms of atrial tachycardia.
As the stated focus of the study was the arrhythmic consequences of structural CHD and surgical interventions, the index arrhythmias were restricted to 3 types: 1) intra-atrial re-entrant tachycardia (IART); 2) focal atrial tachycardia (FAT); and 3) AF. CHD was classified as simple, moderate, or complex based on previous guidelines (3).
In the analysis of the cross-sectional data, 482 patients qualified for study inclusion; IART was the most common initial atrial arrhythmia in 297 patients (61.6%), followed by AF in 139 patients (28.8%) and FAT in 46 patients (9.5%). Patients presenting with IART had a mean age of 28.8 ± 16 years at initial arrhythmia documentation. IART was associated with moderate or complex forms of CHD, with simple forms of CHD in only 42 patients with IART (14%). Patients with FAT as the index arrhythmia had the youngest mean age of onset (23 ± 18 years) and the highest prevalence of the complex CHD.
Conversely, the mean age of the patients with AF as the index arrhythmia was 41 ± 17.2 years, with a greater percentage of simple forms of CHD. Of the total of 138 patients with AF as the index arrhythmia, 73 (53%) were >50 years of age at time of arrhythmia onset. This is perhaps one of the key points of this study—although structural CHD and subsequent hypertrophy, dilation, and fibrosis are undoubtedly significant, traditional factors such as increasing age and hypertension may equally influence the development of AF in CHD patients.
In addition to the cross-sectional analysis of the types of atrial arrhythmias identified at initial presentation, the authors also describe the clinical course using the categorization of paroxysmal, persistent, and permanent atrial arrhythmias. The overall trend reported was that IART and FAT progress from paroxysmal to persistent forms and that AF becomes increasingly permanent as the patients were followed for a mean of 11.3 years post-arrhythmia onset.
The second aspect of this study was the development of new (different) atrial arrhythmias than reported as the index arrhythmia at study entry. Of the 185 patients with either FAT or AF at study entry, only 2 subsequently developed IART during the follow-up; likewise, only 5 of 436 patients developed new-onset FAT during follow-up. This suggests that IART or FAT develop as primary atrial arrhythmias related to surgical incisions, fibrosis, and hypertrophy, and are less likely to develop as a sequel to other atrial arrhythmias.
Conversely, new-onset AF was reported in 42 of 344 patients previously diagnosed with IART or FAT (12.2%), with a total of 181 patients (37.3%) with AF at the end of the study interval. Unfortunately, factors associated with the late or secondary development of AF are not defined in this study. However, a conclusion that persists is that AF develops in all forms of CHD, irrespective of complexity.
The development of AF and attendant comorbidities have evolved as major clinical concerns as patients with CHD survive into middle and advanced ages. This study adds to that possibility by demonstrating the high percentage of atrial fibrillation in those with atrial arrhythmias at age >50 years. Although the study does not provide a denominator with which to determine the incidence of AF in the older CHD population, these findings suggest that AF may eventually surpass IART as the most common atrial arrhythmia in this further aging population.
An equally concerning observation is the gradual evolution of the arrhythmias from paroxysmal to persistent or permanent forms, which increases the risks of heart failure and embolic events, and influences decisions regarding rhythm or rate control.
As the authors acknowledge, patients with the more complex forms of CHD are just now beginning to survive to advanced age. A recent report suggests that AF develops earlier in patients with more complex CHD, with onset at age 36 ± 15 years for complex forms, compared with 47 ± 14 years with moderate and 59 ± 15 years for simple forms of CHD (4).
Regardless, there is the potential for AF to develop in any form of CHD, simple to complex, with age of the patient as an important factor along with the anatomic/hemodynamic substrate. Thus, as the population increases and age of these patients advances, it appears that perhaps the next sequel is slowly being written: a potential AF epidemic in older patients with CHD.
Unfortunately, we are in the earliest stages of understanding the basic interplay among structural CHD, the coexistence of other atrial arrhythmias, and the traditional factors associated with the development of AF. For example, it has been reported that chronic IART results in shortening of the atrial effective refractory period and electrical remodeling, which may facilitate the development of sustained AF (5). Another variation in the development of AF in CHD patients may be the role of nonpulmonary vein foci of continuous electrical activity, related to prior surgical procedures (6).
A natural follow-up to defining patient groups that are at risk for a disease is determining which potential therapies could be preventative. Does aggressive or earlier intervention reduce the proclivity for CHD patients to develop AF? Does a prophylactic “Maze” or “atrial corridor” procedure at the time of CHD surgery offer any benefit—or does extensive atrial dissection result in greater electrophysiological dispersion and an increased risk of AF? Do antiarrhythmic medications have a role in halting or delaying disease progression?
Although this study answers several questions, it raises an even larger number of issues and provides the rationale for future investigations into the true risks of the late development of AF in these patients. As these patients are younger, with more robust AV nodal conduction in the setting of impaired ventricular function or palliated circulatory physiology, the consequences of AF may be catastrophic. Thus, it becomes critical to define the relative risks for the development of AF, to determine which specific forms of CHD are associated with the development of AF, and finally, to establish whether there are therapeutic measures of demonstrable benefit or prevention. AF may be a sequel, but advances in care will likely require a series of advances.
↵∗ Editorials published in the Journal of the American College of Cardiology reflect the views of the authors and do not necessarily represent the views of JACC or the American College of Cardiology.
Both authors have reported that they have no relationships relevant to the contents of this paper to disclose.
- 2017 American College of Cardiology Foundation
- Cambridge Dictionary
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