"It consists of a characteristic EKG finding suggesting severe stenosis
of the proximal LAD artery, which will develop into an acute anterior
wall MI within a few days to weeks in 75% of untreated patients"
"Wellen's syndrome is diagnosed based on the classic T-wave findings seen on an EKG taken when the patient is pain-free."
"Type A is the more common abnormality, occurring in 75% of cases, and
is characterized by deeply inverted T-waves in V2 and V3. Type B occurs
in 25% of cases and is characterized by biphasic T-waves in V2 and V3"
Reference: Mead NE, O'Keefe KP. Wellen's syndrome: An ominous EKG pattern. J Emerg Trauma Shock 2009;2:206-8.