<prompt> Answer this question truthfullyWhat is the syndrome known as Wellens?  <response>: <reason> Wellens syndrome or sign, or occasionally warning is an electrocardiographic manifestation of critical proximal left anterior descending LAD coronary artery stenosis in patients with unstable angina. It is characterized by symmetrical, often deep 2mm, T wave inversions in the anterior precordial leads. A less common variant is biphasic T wave inversions in the same leads. 