Wolff-Parkinson-White (WPW) syndrome is a congenital abnormality that involves an accessory pathway between the atria and the ventricles in addition to the normal atrioventricular node–His pathway. This extra pathway can conduct electrical impulses to the ventricles more quickly and can cause pre-excitation arrhythmias to occur . Three percent to 4% of WPW cases are familial and inherited as an autosomal dominant trait. WPW syndrome has a frequency of 1.5 to 3.1 per 1000 persons in Western countries . The incidence of WPW is higher in men than in women, and it can occur at any age . Therefore, it is inevitable that WPW syndrome can pose a major risk to the small fraction of athletes that have inherited the condition. The following two case reports describe the evaluation of possible WPW syndrome in two Division I collegiate athletes, a female softball player and a female water polo player. Quick detection of the syndrome is vital, and this should be followed by risk stratification and treatment according to the guidelines established by the 36th Bethesda Conference.
Case Number 1
A 19-year-old female freshman collegiate softball player disclosed at her fall pre-participation examination (PPE) that she had WPW syndrome. She was first evaluated by a pediatric cardiologist at age 13 for a cardiac murmur, and was found to have a WPW pattern on electrocardiogram (ECG). A 24-hour ambulatory ECG monitor, an echocardiogram, and an exercise stress test result were all normal. She had no family history of cardiac arrhythmias or sudden death. No treatment was recommended because she was asymptomatic and had no documented paroxysmal supraventricular tachycardia (PSVT). No restriction on her physical activities was recommended.
After her collegiate PPE, she was referred to an arrhythmia specialist for evaluation of WPW pattern on ECG. A 12-lead ECG (Fig. 1) showed the typical WPW pattern with a short PR interval of 0.10 second, a wide QRS complex of 0.12 second, and delta waves negative in lead V1 and positive in leads II and aVF, consistent with a right anteroseptal or midseptal accessory pathway. An exercise stress test showed no inducible arrhythmia; there was persistent accessory pathway conduction at the maximal achieved heart rate of 207 beats per minute. As she had had no symptoms, and there was a significant risk of causing complete heart block during ablation of an anteroseptal accessory pathway, ablation was not recommended at that time. The patient was allowed to continue participation in collegiate athletics, but instructed to follow up should she develop symptoms of palpitations or dizziness.
Shortly thereafter, she began to experience episodes of palpitation during conditioning and base running, but did not mention her condition to any athletic trainer or physician. Her episodes became more frequent in the spring and after the season ended; she then saw a cardiologist in her hometown. She reported that she had a total of about 15 episodes of palpitations associated with some chest pressure and fatigue, but denied lightheadedness, shortness of breath, or syncope. An exercise stress test again demonstrated the persistent accessory pathway conduction, but no exercise induced arrhythmias. As her palpitations were most likely due to a supraventricular tachycardia (SVT) involving this accessory pathway, it was recommended that she undergo cardiac electrophysiologic (EP) testing and radiofrequency (RF) ablation of the accessory pathway. Although no SVT could be induced during the procedure, a manifest accessory pathway was present, and catheter ablation of this pathway was successful in eliminating accessory pathway conduction. Her 12-lead ECG no longer demonstrated evidence of pre-excitation. She rejoined her collegiate softball team at the beginning of her sophomore year, with full clearance to resume competitive sports. She successfully trained and played the entire year with no recurrence of palpitations.
Case Number 2
An 18-year-old freshman collegiate female water polo player disclosed at her fall PPE that she had been diagnosed with WPW 4 years earlier. An abnormal beat was detected by her dentist while she was under anesthesia during a tooth extraction, and she was referred to an academic medical center for further evaluation. There was no family history of cardiac problems or sudden death. She was noted on an exercise test to have evidence of pre-excitation, and underwent an EP study. During the EP study, it was discovered that she had a very benign fascicular ventricular pathway that would cause her no risk in the future. Therefore, no ablation was performed. The patient denied any symptoms of palpitations, lightheadedness, syncope, dyspnea, or chest discomfort. No further cardiac evaluation was recommended.
During her PPE in college, an ECG (Fig. 2) showed sinus rhythm at 54 beats per minute, a short PR interval of 0.12 second, and normal QRS duration of 0.08 second. There was no evidence of delta wave on the resting ECG. She was referred to an arrhythmia specialist for further evaluation. An exercise stress test was recommended to rule out exercise-induced arrhythmias. The patient exercised for 14 minutes, achieving a peak heart rate of 186 beats per minute, which was 90% of her maximal predicted heart rate. The patient had no symptoms. No arrhythmia was inducible with exercise stress. The stress test was normal, and the patient was considered at low risk for participation in sports. She experienced no symptoms her freshman year.
At the onset of her sophomore year under a new coach, the patient occasionally experienced fatigue, light-headedness, dyspnea, and chest discomfort with athletic practice. She admitted that this year's pool workouts were more strenuous and stated that during the exercise treadmill stress tests she had in the past, she was not able to achieve the level of exertion she felt during her conditioning in the pool. She was referred to the arrhythmia specialist for additional consult. Repeat echocardiogram revealed normal findings, and 48-hour ambulatory ECG monitor showed no significant arrhythmia.
The EP study report from the academic medical center 4 years ago was finally received and reviewed. Unfortunately, the actual tracings showing the reported pre-excitation from her first stress test and the EP study were not included. The EP study report stated a diagnosis of probable fasciculoventricular pathway and no inducible SVT. The study also showed no evidence of any accessory pathway connecting the atria and the ventricles to serve as the substrate for a reentrant SVT. As she had neither documented spontaneous arrhythmia nor inducible arrhythmia with stress tests or EP study, she was allowed to continue participation in competitive athletics. It was recommended that she follow up with the arrhythmia specialist in a year.
It is a common perception of the general population that young competitive athletes constitute some of the healthiest members of society. Nevertheless, WPW syndrome can still affect the most vigorous athletes and predispose them to life-threatening dysrhythmias and, although extremely rare, even sudden cardiac death . Yet, before any treatment and decisions on participation in physical activities can be made, WPW syndrome must first be detected.
Although WPW syndrome may be present at birth, it can remain dormant for many years because symptoms of tachycardias may not appear until the teenage years or early adulthood. A WPW tachycardia can go as fast as 150 to 250 beats per minute. The symptoms of tachycardias are caused by the diminished amount of blood delivered to the body and include palpitations, lightheadedness, loss of consciousness, fatigue, and chest pain. It is usually not until these symptoms occur that one is evaluated and then diagnosed with WPW syndrome. It can be detected in an ECG by the appearance of a delta wave inside the QRS wave. Because WPW syndrome can be inherited as an autosomal dominant trait , one should also be evaluated for the syndrome if a first-degree family member has been diagnosed with it. In general, if athletes have experienced any cardiac arrhythmia, the 36th Bethesda Conference dictates that before being considered for physical activity they must undergo noninvasive testing that includes a 12-lead ECG, exercise stress test, and echocardiogram to exclude associated cardiovascular abnormalities. Additionally, a 24-hour ambulatory ECG monitor during athletic activity may also be required .
A clear distinction also needs to be made between WPW syndrome and WPW pattern. In the second case, the athlete reported at her collegiate PPE that she had been diagnosed with WPW. An earlier exercise stress test had reported evidence of pre-excitation, yet the consecutive stress test 4 years later was negative. In general, the appearance of delta waves depends on the location and speed of conduction down the accessory pathway relative to the normal conduction pathway. Adrenaline can facilitate conduction in accessory pathways, causing delta waves to appear during stress even though they may be intermittently present or even absent at rest.
The usual pre-excitation involves a connection between the atria and ventricles; this accessory pathway serves as the substrate for a reentrant SVT. On her EP study, a fasciculoventricular pathway was found. This pathway, which connects the His bundle or bundle branches to the ventricle is a rare variant of pre-excitation. In certain patients there can be other coexisting bypass tracts that can cause arrhythmias. However, in isolation, fasciculoventricular pathways do not cause tachycardias. Therefore, this second athlete displayed a WPW pattern, with only ECG findings, but no inducible arrhythmia and the absence of any other accessory pathways. WPW syndrome refers to those with a ventricular pre-excitation pattern on ECG and clinical SVT.
For athletes who do show symptoms of tachycardias along with the appearance of delta waves, treatment is mandated immediately. Pharmacologic treatment for WPW includes γ-blockers, calcium channel blockers, and digoxin, along with class 1A, 1C, or III antiarrhythmic agents such as procainamide, diltiazem, or verapamil . Besides potential adverse effects such as respiratory distress and emotional lability, cardioactive drugs such as γ-adrenergic blocking agents are banned in some competitive sports including archery and riflery. Furthermore, catecholamines released during physical activity may neutralize the beneficial effects of certain antiarrhythmic agents . These drugs can also negatively impact athletic performance. For example, verapamil and diltiazem can cause dizziness, nausea, headaches, and fatigue. All of these side effects can significantly diminish one's execution during physical activity. Therefore, especially in athletes, RF catheter ablation is a more preferable treatment, with cure rates greater than 95%. Additionally, because symptomatic WPW patients run the slight chance of sudden death (0.02%/patient/year ), they should undergo early RF ablation instead of using pharmacologic agents . During the procedure, RF waves travel through the catheter, and the heat formed by the catheter forms scar tissue on the accessory pathway, preventing the abnormal conduction from passing through. After the RF catheter ablation procedure, it is uncommon for further palpitations or arrhythmias to occur and the athlete can return to physical activity without restrictions. Yet, it is still important to note that 2% of patients undergoing the ablation can experience transient first- or second-degree block, and 1% may have complete heart blockage, which would require implantation of a permanent pacemaker and prematurely terminate an athlete's career . Most inadvertent complete heart blocks occur in the setting of attempted ablation of septal accessory pathways located close to the AV junction.
In asymptomatic athletes who have had no prior history of palpitations or tachycardia, and no evidence of cardiac abnormalities, it continues to be debated on what guidelines to follow. For asymptomatic athletes who participate in moderate or high level activity, it has been advised that they undergo an EP study. If the athlete has multiple accessory pathways or ventricular rates exceeding 240 beats per minute, he or she should undergo catheter ablation of the superfluous pathway . In a randomized study of asymptomatic patients with WPW syndrome at high risk for arrhythmias (defined as ≤ 35 years old in whom arrhythmias were reproducibly induced), prophylactic catheter ablation resulted in a risk reduction of 92% over a 5-year follow-up period . In addition, one third of asymptomatic individuals younger than 40 years of age when pre-excitation was identified eventually developed symptoms, whereas no patients in whom pre-excitation was first uncovered after the age of 40 years developed symptoms .
When WPW syndrome is detected in an athlete, it is imperative that the choice of treatment be based on the risk that the patient faces. As Table 1 indicates, if a patient begins to develop symptoms associated with WPW, he or she should undergo RF catheter ablation. However, for asymptomatic patients, one must first categorize the level of physical activity. If the activity level is undemanding, no further treatment is recommended. However, for moderate to rigorous activity, further EP studies must be conducted to determine if the patient should be cured via ablation. For those asymptomatic patients who are engaged in high-risk activities, such as airplane pilots or bus drivers, the decision to ablate pathways is made on the basis of individual clinical considerations . The risk of ventricular arrhythmia could cause severe consequences not only for the patient but for others as well. The results of EP testing can be an important predictor of arrhythmic events in patients with asymptomatic pre-excitation. After RF catheter ablation, the patient should wait 2 to 4 weeks before returning to action. Additionally, team physicians must keep in mind that although the sport itself may be nonstrenuous, the training demanded of these athletes may be classified as strenuous. For example, even though golf seems physically undemanding, the athletes may still have rigorous conditioning that includes running and lifting weights. Lastly, as illustrated by the second case report, one cannot always rely on the patient to provide reliable information. It is often necessary to retrieve former records and perform an independent study of the patient to arrive at definitive conclusions. By following these suggestions and the guidelines formed under the 36th Bethesda Conference, team physicians, with assistance from their consulting cardiologists, should be comfortable in evaluating and diagnosing an athlete with WPW syndrome, and make a determination regarding safe return to play.