This 63-year-old woman, known for the past 5 years to have a dilated cardiomyopathy of unknown etiology, is brought to the Emergency Department, complaining of sudden onset of rapid palpitation and dyspnea:

• Ventricular tachycardia with 2:1 retrograde ventriculo-atrial conduction
• Left axis deviation

Comment: In favor of the diagnosis of ventricular tachycardia:

• The width of the QRS (>140 msec.)
• The 2:1 ventriculo-atrial conduction
• The positive concordance in the chest leads (positive QRS from V1 to V6)

The ventricular tachycardia subsides spontaneously 20 minutes after arrival. On the following day palpitation recurs:

• Sinus rhythm followed by ventricular tachycardia (rate 153/min)
• Transient 2:1 ventricular-atrial conduction and one AV capture