Wellen's phenomenon occurs when biphasic T waves are seen in leads V1-V3 OR deep symmetric inverted T waves are seen in the precordial leads. Both of these ECG findings are indicative of a severe proximal left anterior descending stenosis (acute or chronic). Note that there is NO ST segement elevation that occurs with Wellen's ECG changes.
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2. Chou's Electrocardiography in Clinical Practice: Adult and Pediatric, 6e
By Steven Lome