Malignant vasovagal syndrome in two patients with Wolff-Parkinson-White syndrome.

The presence of Wolff-Parkinson-White (WPW) syndrome in patients presenting with syncope suggests that tachyarrhythmia may be the cause. However, the symptoms require careful evaluation. Two young patients presented with syncope and were found to have WPW syndrome on their ECG. In both patients symptoms were suggestive of vasovagal syncope. During tilt testing, both the patients developed their typical symptoms with a fall in blood pressure and heart rate confirming the diagnosis of malignant vasovagal syndrome.