Wolff-Parkinson-White syndrome: disappearance of preexcitation and appearance of complete heart block, probably due to myocardial infarction.

The appearance and gradual progression of atrioventricular (A-V) block in the presence of the Wolff-Parkinson-White (WPW) syndrome is an intriguing phenomenon. The vast majority of the reports up to date describe persistence of preexcitation in the face of partial or complete heart block. We describe a patient with severe coronary artery disease, in whom WPW disappeared suddenly, transiently at first, during coronary bypass surgery, and then permanently, probably as a result of an acute myocardial infarction, and in whom all the sinus beats during relentlessly progressive heart block were conducted through the normal A-V conduction system only.