Atrial myocarditis causing transient sinoatrial disease (incessant atr
ial tachycardia alternating with sinoatrial pauses of up to 6 s in dur
ation) in an athlete is reported. Diagnosis was undertaken by endomyoc
ardial biopsy; biventricular and right atrial specimens were obtained.
After a 6-month rest period, the atrial arrhythmias disappeared, and
the athlete was able to resume his professional sporting activities.