title: Abolition of exercise induced positive U-wave after coronary angioplasty: clinical implication.
abstract: OBJECTIVE
  We prospectively studied the course of exercise induced positive U-wave before and after percutaneous transluminal coronary angioplasty (angioplasty).
  
  
  BACKGROUND
  Negative U-wave in ECG is known to be associated with the myocardial ischemia in the territory of the left anterior descending artery. Positive U-wave needs further evaluation to prove its diagnostic value in localization of coronary artery disease.
  
  
  METHODS
  Twenty patients demonstrated exercise induced positive U-wave from a cohort of 730 patients referred because of chest pain. Exercise was carried to > or =90% of target heart rate. They underwent angiography and subsequent angioplasty for stenosis of 70% or greater. The exercise test was repeated post angioplasty. Careful screening for clinical endpoints and presence of ST segment depression and positive U-wave was done during exercise and the first 3 min of the recovery phase.
  
  
  RESULTS
  Fifteen patients had isolated exercise induced U-wave and five had additional ST segment depression of > or =1 mm. Significant stenosis (>70% diameter reduction) of the circumflex artery was seen in 11 (55%) and of the right coronary artery in 9 (45%) patients. Coronary artery stenosis was reduced from 90+/-2% to 13+/-1% (mean+/-S.D.) P<0.001. On repeat of the exercise test U-wave and ST depression disappeared in all 20 individuals. Effort tolerance was improved after angioplasty for a mean duration of 3 min and 38 s, P<0.001.
  
  
  CONCLUSIONS
  Exercise induced positive U-wave is an infrequent but specific marker of significant single coronary (circumflex or right) artery stenosis. It may lend itself to the detection of restenosis.
authors.affiliation: Cardiac Catheterization Laboratories, Chest Diseases Hospital, Faculty of Medicine, Kuwait University, PO Box 24923, 13110, Safat, Kuwait.
authors.forename: N H
authors.initials: NH
authors.lastname: Hayat
authors.forename: H
authors.initials: H
authors.lastname: Salman
authors.forename: M A
authors.initials: MA
authors.lastname: Daimee
authors.forename: C S
authors.initials: CS
authors.lastname: Thomas
mesh_terms: D000328:Adult; D015906:Angioplasty, Balloon, Coronary; D017023:Coronary Angiography; D003327:Coronary Disease / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000628:therapy; D004562:Electrocardiography; D005080:Exercise Test; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011446:Prospective Studies