Q: Negative U wave on EKG during exercise testing correlates with stenosis of which coronary vessels?
A) The left main
B) Left anterior descending coronary artery (LAD)
C) Posterior descending artery
D) A and B
E) All of the above
U waves on EKG are usually positive deflections and best visible on leads V2 to V4. They are well known in clinical practice due to their association with hypokalemia and intracranial hemorrhage. U wave's polarity may reverse during myocardial ischemia. Negative U waves during exercise stress test is highly suggestive of ischemia from left main or LAD artery.