Abolition of exercise induced positive U-wave after coronary angioplasty: clinical implication

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. Method: Twenty patients demonstrated exercise induced positive U-wave from a cohort of 730 patients referred because of chest pain. Exercise was carried to ≥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 ≥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. Conclusion: 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.