I don't believe anyone can safely say what the interaction of a specific medication (ephedrine) may have on an individual's system without some knowledge of pharmacology and current/past health history.
Ephedrine is a central nervous system stimulant, and that can have heart rhythm implications such as increase heart rate, and if conditions involving arrhythmia as with WPW, the results of a fast heart rate with WPW may be difficult to predict.
The prescribing doctor and/or the pharmacist may be in a better postion to answer your questions. Thanks for sharing, and wish you the best for healthful outcome.
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