Syncope in an Athlete With Intermittent Pre-Excitation
A 15-year-old competitive swimmer reports three episodes of sudden palpitations at practice, each lasting 5-10 minutes and terminating with a Valsalva maneuver. Last week he had a syncopal episode at the pool: he was pulled from the water, was pale, and recovered within 30 seconds without confusion or tonic activity. The ECG shows PR 0.09 s, a delta wave, QRS 0.14 s, and a normal axis. Holter monitoring shows intermittent pre-excitation, and during exercise testing the delta wave disappears abruptly above 130 bpm. Echocardiography is structurally normal. He has been selected for a national training camp in 3 weeks; the family asks whether he can go and whether he really needs an ablation.
1. How do you risk-stratify this patient, and what does each finding mean?
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Findings and their weight
- Intermittent pre-excitation and abrupt loss of the delta wave with exercise suggest a long accessory pathway effective refractory period and a low likelihood of rapid antegrade conduction during atrial fibrillation. This is reassuring but does not prove zero risk.
- Syncope is the red flag. It requires a cause: tachyarrhythmia with hemodynamic compromise, neurally mediated syncope during the Valsalva, or something unrelated. In a swimmer, syncope in water is a potentially lethal event regardless of cause.
- Palpitations with documented delta wave make AV re-entry the most likely mechanism and confirm that the pathway is a conductor.
- Structural normality and normal axis reduce concern for Ebstein anomaly or a fasciculoventricular fiber, but do not exclude a high-risk pathway.
What to add Electrophysiology study with isoproterenol to measure antegrade and retrograde refractory periods and inducible arrhythmia, ideally with a plan to ablate in the same setting. Risk is not determined by the resting ECG alone.
2. What is your management plan regarding the training camp and ablation, and what do you tell the family?
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Plan
- Recommend that he does not attend the camp and does not swim competitively until the pathway has been treated. Competitive athletes with symptomatic WPW or high-risk features should undergo catheter ablation, and participation in sport should wait until it is completed and confirmed.
- Expedite electrophysiology study, ideally within 1-2 weeks, with consent for ablation at the same procedure.
- Typical restriction after successful ablation is 1-4 weeks depending on access-site healing and institutional practice, before a graduated return; guidelines generally permit competitive sport after successful ablation.
Counseling
- Be direct about uncertainty: sudden-death risk from WPW is low but not zero, and the risk of drowning makes swimming a special case.
- Explain the ablation procedure, success rates (high for a single pathway), and risks: heart block if the pathway is septal, coronary injury, perforation, and recurrence needing a second procedure.
- If ablation fails or the pathway is adjacent to the AV node, discuss repeat ablation, surgical cryoablation, or continued restriction with antiarrhythmic coverage rather than returning to unrestricted swimming.
3. The family says his resting ECG is "not that bad" and asks whether an event has to happen before treating. How do you respond?
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Acknowledge the logic, then correct the premise. A single syncopal episode is itself an event, and in water it could have been fatal. Pre-excitation on a resting ECG reflects the pathway's existence, not its conduction characteristics, so a "mild-looking" delta wave does not reliably predict risk.
Explain that the decision is not purely medical: it depends on his goals and on what he is willing to accept. Frame the options with concrete consequences:
- Ablation now: high chance of cure, small procedural risk, a few weeks out of the water.
- Deferral with restriction: avoids procedural risk but requires him to give up competitive swimming indefinitely and leaves the arrhythmia untreated.
- Deferral without restriction: available to him, but he should know the team advises against it.
Document the conversation, offer a second opinion from electrophysiology, and involve the parents and the athlete in the final decision. Reassure them that this is a manageable condition and that most athletes return to full competition after successful ablation.