Do All Brugada Patients Need an ICD?
Abstract & Commentary
By John P. DiMarco, MD, PhD, Professor of Medicine, Division of Cardiology, University of Virginia, Charlottesville. Dr. DiMarco is a consultant for Novartis, and does research for Medtronic and Guidant.
Source: Sacher F, et al. Outcome After Implantation of a Cardioverter-Defibrillator in Patients With Brugada Syndrome: A Multicenter Study. Circulation. 2006;114:2317-2324.
Sacher and colleagues collected data on all patients diagnosed with Brugada syndrome who received an implantable cardioverter defibrillator (ICD) in 14 centers between 1993 and 2005. Patients were included only if they had a Brugada type 1 ECG at baseline, either during a routine recording or after provocation with a class I antiarrhythmic drug. A type 1 ECG was defined as a tracing with prominent coved ST-segment elevation with either J-wave amplitude or ST segment elevation > 2 mm followed by a negative T wave. Clinical data were collected on all patients. Patients were characterized by 3 types of presentation: resuscitated cardiac arrest, undocumented syncope, or asymptomatic. Electrophysiologic testing results were classified as positive if any ventricular arrhythmia lasting greater than 30 seconds could be initiated with a protocol of < 3 ventricular stimuli. All patients received transvenous ICD's using standard approaches. Patients were followed after implant with routine visits every 3 to 9 months or after shocks.
The study group included 220 patients; 83% male, mean age 46 + 12 years. A type 1 ECG was found spontaneously at baseline in 137 patients. In the remaining 83 patients, class I antiarrhythmic drug administration was necessary to reveal a diagnostic type 1 ECG. Genetic testing for a SCN5a mutation was performed in 97 patients and a mutation was identified in 29. At the time of entry into the study, 114 patients were asymptomatic, 88 had previously experienced syncope with no identified extracardiac cause and 18 patients had been resuscitated from an episode of ventricular fibrillation (VF). Among the asymptomatic patients, a type 1 Brugada ECG pattern and inducible ventricular arrhythmia at EP study was the indication for ICD therapy in 99 (87%) patients. ICD recipients who had negative EP studies had either a positive family history or spontaneous nonsustained ventricular arrhythmias. Supraventricular arrhythmias were present in 32 of 220 patients (15%).
Patients were followed for a median of 31 months (range 1 to 150 months) after ICD implantation. There were no deaths. In the total population, 8% experienced appropriate shocks. Appropriate shocks occurred in 22% of those with resuscitated cardiac death, 10% of those with syncope and only 4% of those who were initially asymptomatic. Inappropriate shocks occurred in 20% of the patients with an even frequency in the 3 groups. Most appropriate shocks were for polymorphic ventricular tachycardia (VT) or ventricular fibrillation (16 patients); only 2 patients had shocks for monomorphic VT. Among patients who received shocks, the median number of shocks was 4 (range of 1 to 65) with shocks occurring a median of 16 (range 1 to 140) months after ICD implantation. A Cox proportional hazards model identified the presence of documented resuscitated cardiac arrest before implantation as the only factor predictive of appropriate device discharge.
ICD complications were noted in 62 of 220 patients (28%). Early complications included: pneumothoraces (3), pericardial effusions (2), lead displacements (5), vein thrombosis (2), and hematoma (2). At the time of implant, high defibrillation thresholds were noted in 24 of 160 patients and 53 had a high pacing threshold either at implantation or during follow-up. Late complications included lead malfunction requiring extraction or reimplantation (19), infection (3), pericardia effusion (1), pocket revisions (2), device failure (1), and psychological disturbance (2). Inappropriate shocks for either lead malfunction (19), T wave oversensing (10), sinus tachycardia (10), and supraventricular arrhythmias (9) were seen in 45 patients (20%, 4 + 3 shocks per patient). Factors predictive of inappropriate shocks were history of supraventricular tachycardia, T wave oversensing and low R wave amplitude at implant.
The authors conclude that there is a relatively low incidence of arrhythmic events in patients with Brugada syndrome, particularly those who do not have a documented sustained arrhythmia at the time of diagnosis. During follow-up there is a significant risk of device related complications and inappropriate shocks are 2.5 times more frequent than appropriate ones.
Commentary
This large multicenter survey illustrates some of the dilemmas physicians face when they encounter patients with an ECG suggestive of the Brugada syndrome. Among patients with documented sustained arrhythmias, a consensus has been reached that ICD therapy is appropriate. Indeed, most antiarrhythmic drugs are completely ineffective. In this series, however, only 4 of 18 patients with a prior resuscitated arrest, the highest risk group, experienced appropriate shocks. Among patients with syncope, appropriate shocks were noted in 10% and noncardiac causes for syncope were identified in another 7%. Among asymptomatic individuals, only 4% received appropriate shocks during a follow-up of over 2.5 years. Clearly, predicting arrhythmic events in Brugada patients is difficult. In all 3 groups, both device complications and inappropriate shock therapy were relatively common. This makes strategies to better risk stratify patients, particularly those without documented arrhythmias, all the more important. Unfortunately, data presented here do not really help us better select patients with a Brugada type ECG for ICD therapy. Although 75% of the patients with syncope and 86% of the asymptomatic patients had inducible arrhythmias at electrophysiologic study, the event rates in both groups were low. Among the patients with resuscitated sudden death, only 4 of 11 had an inducible arrhythmia. The presence of a spontaneous type 1 ECG and the finding of a SCN5a mutation were also not significant predictors for appropriate shocks.
The most feared clinical manifestation of Brugada syndrome is sudden death. Patients are usually young and healthy when they are identified. Still, in this study, even in patients selected by strict criteria, the annual event rate appears to be low and is considerably less than the rate of complication of ICD therapy. Physicians dealing with asymptomatic patients with Brugada type ECG's must therefore make a difficult analysis of the risks and benefits in each individual before concluding that ICD therapy is appropriate.
Sacher and colleagues collected data on all patients diagnosed with Brugada syndrome who received an implantable cardioverter defibrillator (ICD) in 14 centers between 1993 and 2005.You have reached your article limit for the month. Subscribe now to access this article plus other member-only content.
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