The RBBB is referred to as “pseudo” because true RBBB has a widened S wave in the lateral leads. In Brugada syndrome, there is early high takeoff of the ST segment in the right precordial leads (actually the J wave), which looks like an RBBB pattern [5••]. The other key features of the Brugada syndrome ECG are extrasystoles, and when the patient is symptomatic, rapid polymorphic ventricular tachycardia (VT) may be indistinguishable from VF [4•].
Electrocardiographic findings are recognized prior to manifestation of symptoms because frequently there are no symptoms other than sudden death in a patient with Brugada syndrome. Often, a patient is sleeping and dies suddenly in the early morning, after having gone into polymorphic VT [9••]. Patients may present with syncope, or presyncope and palpitations. Nocturnal agonal respirations have also been described. Patients may report a family history of sudden death or VF. In fact, often the family history is the most important part of the encounter with a patient with suspected Brugada syndrome, as the past medical history and physical examination are unremarkable . Onset of arrhythmias range from age 22 to 65, with a peak in the fourth decade [5•].
A key feature in the diagnosis of Brugada syndrome is the inducibility of ECG changes with a drug challenge. This type of evaluation is useful, for example, in the patient who presents with syncope and a family history of sudden death. The patient is placed on continuous blood pressure and ECG monitoring, with defibrillator and advanced cardiac life support facilities immediately available. A Class Ia sodium channel blocker (ajmaline, flecanide, or procainamide) is administered and ECG changes in the precordial leads are observed. The test is positive when a normal baseline ECG develops a J-wave amplitude of 2 mm in two of leads V1 to V3, or when a person with saddleback ST-segment elevation (Types II and III) converts to coved-type ST-segment elevation (Type I) [7••]. The patient is then monitored until the ECG normalizes.
Current recommendations for the diagnosis of Brugada syndrome require a patient to have the following: 1) a baseline ECG with saddleback ST-segment elevation in more than one precordial lead, which converts to a coved Type I after sodium channel blocker challenge, and one of either documented VF, polymorphic VT, family history of SCD before age 45, family history of coved-type ST elevation, inducible changes on an electrophysiologic study, history of syncope, or history of agonal respirations; or 2) coved (Type I) ST-segment elevation in more than one precordial lead and one of the above list [9••].
Although the diagnostic criteria for Brugada syndrome are fairly specific, other conditions should be considered in the differential diagnosis. Arrhythmogenic right ventricular cardiomyopathy (ARVC) is similar to Brugada syndrome and should be excluded. Although both conditions may produce syncope, cardiac arrest, and sudden death from VT, ARVC has characteristic inverted T waves precordially, does not have the same effects from sodium channel blockers and β-agonists, and will usually show fibrofatty involvement histologically [9••]. Other conditions which can lead to V1 to V3 ST-segment elevation include cocaine intoxication, hypercalcemia, hyperkalemia, tricyclic antidepressant overdose, right and left bundle branch block, left ventricular hypertrophy, acute myocardial infarction, myocarditis, pulmonary embolism, aortic aneurism, and Duchenne muscular dystrophy [9••].
Previous treatment options for asymptomatic Brugada syndrome patients included no intervention, pharmacologic antiarrhythmics (β-blockers or amiodarone), or an implantable cardiac defibrillator (ICD). The ICD is the present treatment of choice, as studies have proven it effective in terminating VF episodes . One study showed a 10% annual mortality with β-blockers, which is not acceptable given the demonstrated effectiveness of the ICD . The most pressing question currently, revolves around who is an appropriate candidate for ICD placement due to a significant number of Brugada syndrome patients being asymptomatic. The 2002 American College of Cardiology/American Heart Association/North American Society for Pacing and Electrophysiology Committee on Pacemaker Implantation recommends ICD placement in Brugada syndrome patients who have experienced syncope or have a family history of SCD due to the high incidence of VF . The committee did not recommend ICD placement in Brugada syndrome individuals who only exhibit ECG findings.
Brugada syndrome patients can be broken down into three risk groups: high (history of syncope and baseline ST elevation), intermediate (no history of syncope and only baseline ST elevation), and low (SCN5A mutation carrier or ECG change induced with drug challenge).
High-risk patients are ICD candidates, intermediate-risk patients have undetermined treatment recommendations, and low-risk patients should be advised to avoid tricyclic antidepressants and sodium channel blockers and to seek care if presyncope or syncope develops .
Another study based prognosis on an individual's symptom and ECG findings . One must consider whether the ECG showed a Brugada pattern spontaneously or only after induction with a sodium channel blocker. These two groups of patients were further broken down based on whether or not VF could be induced with programmed ventricular stimulation. Patients diagnosed with Brugada syndrome based on a spontaneously abnormal ECG, with no history of syncope, have a 1.8% risk of sudden death in 2 years if no arrhythmia could be induced, compared with a 14.0% risk if arrhythmia could be induced. Those with an abnormal ECG, history of syncope, and inducible arrhythmia on ECG are at the most risk, with a 27% risk of dying within 2 years. Patients with only an abnormal ECG after drug challenge and no history of syncope or arrhythmia after ventricular stimulation, are at the least risk, 0.5% .
A sports medicine physician is often expected to screen potential athletes for medical conditions that may predispose them to injury or illness preventing their participation. The goal of cardiovascular screening in young athletes is early recognition of congenital heart disease to reduce the risk and prevent adverse arrhythmic events leading to sudden nontraumatic cardiac death. In the past, the medical community has focused on structural cardiac anomalies in the young and coronary artery disease in the elderly. Along with hypertrophic cardiomyopathy, anomalous coronary artery origin, right ventricular dysplasia, Wolff-Parkinson-White syndrome, and long QT syndrome, Brugada syndrome is one of the indolent conditions that should be considered during cardiovascular screening.
History and physical examination are the first steps in screening and a history of syncope, palpitations, nocturnal agonal respirations, and family history of sudden death all should prompt consideration of the Brugada syndrome. Although the physical examination will be unrevealing, the ECG findings are classic. Echocardiogram is not recommended in routine sports screening and would not be helpful in the case of Brugada syndrome .
What is a sports medicine physician to tell an athlete with Brugada syndrome? Brugada syndrome is unique among cardiovascular risks in that the associated arrhythmias occur at rest and may be inhibited by the increased adrenergic tone produced during exercise. The American Heart Association recommends safe guidelines for athletic participation of young athletes diagnosed with genetic cardiovascular diseases. Although little empiric data is available for making recommendations regarding athletes diagnosed with Brugada syndrome, they draw on what data they find as well as on personal and collective experience .
Patients with Brugada syndrome are strongly discouraged from body building, windsurfing, hockey, lifting free weights, rock climbing, underwater (SCUBA) diving, and downhill skiing. There are uncertain recommendations for participation in basketball, singles tennis, racquetball, flag football, sprinting, motorcycling, soccer, and horseback riding. Brugada syndrome patients are likely safe to participate in cross country skiing, doubles tennis, baseball, bowling, biking, golf, hiking, skating, jogging, snorkeling, sailing, using weight machines, swimming, and walking.
Brugada syndrome patients are advised to be wary of overheating, as temperature-dependent dysfunction of the SCN5A gene has been observed. Patients with an ICD should be prohibited from contact sports due in part to disruption of leads. Sinus tachycardia from exercise may trigger inappropriate ICD shock and therefore well programmed dual chamber ICD cardioverters should be utilized .
Sudden cardiac death due to Brugada syndrome most often occurs in young, otherwise healthy individuals. This is the very population that seeks to participate in sports. Therefore, the sports medicine physician must be astutely aware of this condition when screening patients for athletic participation. Should the characteristic ECG changes be discovered, it is the role of the sports medicine physician to work with the athlete in designing an exercise prescription. This depends largely on the physician-patient relationship and an understanding of the specific needs of the athlete. Recommendations must be used in combination with considerations of the sports environment, patient medications, and even emotional/social context of sports participation for the individual. The relatively recent discovery of Brugada syndrome and the active field of research surrounding it suggest that there is much more information forthcoming regarding management of this unique group of athletes.
The opinions and assertions contained herein are the private views of the authors and are not to be construed as official or as reflecting the views of the Army Medical Department or the Army Service at large.
The authors would like to acknowledge three physicians: Colonel Francis G. O'Connor, MD, Colonel Thomas P. Dove, MD, and Captain John E. Thomas, MD in helping prepare the paper.
References and Recommended Reading
Papers of particular interest, published recently, have been highlighted as: • Of importance, •• Of major importance
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© 2005 American College of Sports Medicine
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