Normal P waves and short PR (<120 msec). Initial slurring of the QRS (delta wave) in at least two of the three orthogonal leads (I, aVF, V2). Secondary ST and T changes.

Normal P waves and short PR (<120 msec). Initial slurring of the QRS (delta wave) in at least two of the three orthogonal leads (I, aVF, V2). Secondary ST and T changes.