Patients showed milder forms of Brugada syndrome upon diagnosis in more recent years, a registry study suggested.
In contrast, those enrolled in the registry before release of the 2002 consensus document on Brugada syndrome were more symptomatic on diagnosis. When first told that they had the genetic disorder, these early patients were more likely than patients diagnosed after 2002 to have had:
- Aborted sudden death (12.1% versus 4.6%, P=0.005)
- Inducibility during programmed electrical stimulation (PES; 34.4% versus 19.2%, P<0.001)
- A spontaneous type 1 electrocardiogram (50.3% versus 26.2%, P=0.0002)
"Since being first described, the presentation of Brugada syndrome has changed," wrote authors Ruben Casado-Arroyo, MD, PhD, of Erasmus Hospital in Brussels, Belgium, and colleagues in the August 9 issue of the Journal of the American College of Cardiology.
"As a result, there is a clear shift toward milder forms of the syndrome due to a better identification of patients," they wrote. "We are starting a new era of the disease, with patients who are greater in number but who are less symptomatic."
During follow-up, the annual rate of arrhythmic events was higher in patients diagnosed before versus after 2002 (2.5% versus 1.8%, P<0.001).When these events were broken down, recurrent arrhythmia (19% versus 5%, P=0.007) and inappropriate shocks (26.6% versus 12.1%, P=0.026) were more common in the early group. Atrial fibrillation rates were no different between cohorts, however (9.1% versus 3.2%, P=0.07).
PES inducibility -- an invasive test for Brugada syndrome -- was independently linked to arrhythmic events in the early registry participants (HR 4.44, 95% CI 1.94-10.14), but not the later ones (HR 2.26, 95% CI 0.54-9.50).
This invites questioning the role of PES, Andrea Mazzanti, MD, and Silvia G. Priori, MD, PhD, both of Italy's Salvatore Maugeri Foundation, suggested. The duo pointed out in their accompanying editorial that Casado-Arroyo's group had reported the predictive value of PES more than a decade ago.
"This is particularly relevant," they wrote, "when considering that over the past 2 decades, the field has been unable to progress beyond the dichotomy set up by discrepant results concerning the value of PES in predicting the risk of sudden cardiac death and identifying those who should receive an implantable defibrillator."
Mazzanti and Priori wrote that they were "convinced that the lack of a spontaneous type 1 pattern on the electrocardiogram is the most valuable marker of low risk" now.
"With the low incidence of events published in other series, tests like [PES] may no longer have a predictive value because the pre-test probability of [sudden cardiac death] might not be sufficiently high to allow recognition of significant differences," conceded Casado-Arroyo's group.
Hence, "the indication for implantable cardioverter-defibrillator [ICD] implantation should be made on the basis of all clinical information about the patient and not solely on one isolated clinical variable or test."
Relatively younger patients diagnosed with Brugada syndrome may benefit from extra life years associated with ICD therapy. "Currently, the only proven therapy to prevent sudden cardiac death in patients with Brugada Syndrome is ICD implantation, although this intervention is not without complications," the authors wrote.
Their study included 447 patients who were the first to be diagnosed with Brugada Syndrome in their families. The study population was divided into those diagnosed in 1986-2002 (n=165) and in 2003-2014 (n=282). Each participant was enrolled in a dual-center European registry and followed prospectively for 50 months on average.
Despite 28 years of data, Casado-Arroyo and colleagues acknowledged that their follow-up period was still too short to make conclusions about a lifelong disease.
"It is unknown whether the 1.5% annual event rate found in studies with a relatively short observation time will apply to follow-ups of 20 to 25 years," the editorialists agreed.
The study was funded by a post-graduate research grant.
Casado-Arroyo and Mazzanti reported no relevant conflicts of interest.
One study co-author disclosed relationships with Biotronik, Boston Scientific, Medtronic, St. Jude Medical, and Sorin.
Priori disclosed advising for Medtronic and Boston Scientific; receiving research grants from Boston Scientific and Gilead; working for the creation of intellectual property owned by the Fondazione Maugeri; and holding equity in Audentes Rx.
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