False-positive exercise stress electrocardiogram due to accessory pathway in the absence of manifest preexcitation

False-positive exercise testing in patients with an accessory pathway has been described only in patients with manifest preexcitation during exercise. We describe a patient in whom marked ST-segment changes were seen during an exercise test in the absence of any preexcitation of the QRS complexes. The role of the accessory pathway in producing the ST changes was reaffirmed by absence of this abnormality following catheter ablation of the accessory pathway.