Prognostic Predictors in Brugada Syndrome
Prognostic Predictors in Brugada Syndrome
Abstract & Commentary
By John P. DiMarco, MD, PhD, Professor of Medicine, Division of Cardiology, University of Virginia, Charlottesville
Source: Priori SG, et al. Risk stratification in brugada syndrome: Results of the PRELUDE (PRogrammed ELectrical stimUlation preDictive valuE) registry. J Am Coll Cardiol 2012;59:37-45.
In this paper, Priori and colleagues from a consortium of 10 Italian arrhythmia centers enrolled Brugada syndrome patients to evaluate the role of programmed electrical stimulation in risk stratification and to look for other novel predictors of outcome in Brugada syndrome patients. Patients were enrolled if they were older than 18 years, had either a spontaneous or pharmacologically induced Brugada type 1 ECG pattern (coved ST segment elevation greater than 2 mm in at least two right precordial leads), and had never experienced either cardiac arrest or sustained ventricular tachycardia. All ECGs were analyzed at a central coordinating center with special attention paid to the morphology of the QRS complex and ST segment. Structural cardiac abnormalities were excluded by echocardiography and exercise testing. Patients underwent electrophysiologic (EP) study to assess the inducibility of ventricular arrhythmias. A standard protocol using three extrastimuli at two right ventricular sites was employed. A patient was considered to have an inducible arrhythmia if sustained ventricular fibrillation or sustained polymorphic ventricular tachycardia were induced. Reproducibility of arrhythmia induction was tested at the same procedure at the operator's discretion. After their EP study, physicians were free to manage their patients as they felt appropriate. During follow-up, arrhythmia events were defined as the occurrence of ventricular fibrillation or appropriate implantable cardioverter-defibrillators (ICD) interventions. Follow-up visits were made at 3 months after EP study and then every 6 months until March 2010.
The Prelude Registry enrolled 308 patients. The mean age at enrollment was 47 ± 12 years and 80% were male. The Brugada type 1 ECG pattern was seen spontaneously in 56% and was induced with intravenous drug challenge in the remaining 44%. QRS fragmentation (defined as two or more spikes within the QRS complex in lead V1 to V3) was present in 8.1% of the patients. Genetic analysis was performed in 123 patients and an SCN5A mutation was identified in 20% of the tested patients. Before enrollment, 65 patients (21%) had experienced at least one syncopal spell. During follow-up of 39 ± 12 months, 14 of 308 (4.5%) of patients experienced cardiac arrest or documented ventricular fibrillation. All patients were resuscitated with either an ICD shock (13) or by an emergency medical team (1).
At electrophysiologic study, 126 of 308 patients (41%) had an inducible arrhythmia. Arrhythmias were inducible with a single extrastimulus in seven patients, with two extrastimuli in 56 patients and with three extrastimuli in 63 patients. Of note, among patients in whom short-term reproducibility was tested, only 44% of the patients had reproducible arrhythmia induction. An ICD was inserted in 98 of 126 patients with induced arrhythmia and in 39 of 182 patients without inducible arrhythmia. During follow-up, there were 14 events in the 308 patients for an annual event rate of 1.5%. Programmed electrical stimulation had no predictive value. There were five arrhythmic events among 126 patients with inducible arrhythmias (3.9%) compared to nine arrhythmic events among 182 patients with no inducible arrhythmias (4.9%). However, several factors were predictive of outcome. These included a history of syncope, a spontaneous type 1 ECG pattern, a ventricular effective refractory period < 200 msec, and QRS fragmentation. The most powerful predictor of an arrhythmic event was the presence of both syncope and a spontaneous type 1 ECG pattern.
The authors then compared their data to three other studies that looked at the natural history of patients with Brugada syndrome. They found their data to be similar to two earlier reports but considerably lower than the series reported by Brugada et al, which had an annual event rate of 4.1%.1
The authors conclude that the PRELUDE Registry indicates that programmed electrical stimulation should not be used to assess prognosis in patients with Brugada syndrome. The most valuable prognostic clinical factors are a history of syncope, the presence of a spontaneous type 1 ECG pattern, and QRS fragmentation.
Commentary
Management of patients with the Brugada syndrome ECG pattern, but no documented arrhythmias, has been controversial. ICDs are the only accepted approach in patients who require treatment since no pharmacologic therapy has been shown to be effective. The event rate in asymptomatic Brugada syndrome patients is fairly low and many patients are identified as young adults. Given the complications associated with long-term ICD therapy, it would be of value if effective risk stratification were possible. Prior reports by Brugada et al suggested that programmed ventricular stimulation was an effective tool for this purpose. Unfortunately, the data presented here from a large prospective registry suggest that programmed electrical stimulation is of no benefit as a risk stratification tool since it has poor positive and negative predictive value. These new data are in agreement with data from two other reports and the combined data should lead electrophysiologists to abandon the use of stimulation studies in these patients. Patients with syncope and a Type I ECG pattern should certainly receive an ICD. Patients with syncope and a provocable ECG pattern are also appropriate candidates. For asymptomatic patients, it is likely that a risk scoring system based on data from several combined registries will have to be devised.
Reference
1. Brugada P, et al. Natural history of Brugada syndrome: The prognostic value of programmed electrical stimulation of the heart. J Cardiovasc Electrophysiol 2003;14:455-457.
In this paper, Priori and colleagues from a consortium of 10 Italian arrhythmia centers enrolled Brugada syndrome patients to evaluate the role of programmed electrical stimulation in risk stratification and to look for other novel predictors of outcome in Brugada syndrome patients.Subscribe Now for Access
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