Echocardiographic studies of dobutamine-induced ST-segment elevation before and after coronary artery bypass grafting in patients with old Q-wave myocardial infarction

There is a controversy regarding the functional significance of stress-indu ced ST-segment elevation (STE) in Q leads. However, the effect of revascula rization on the induction of STE was not investigated. We studied 35 patien ts with old Q-wave myocardial infarction who underwent coronary artery bypa ss grafting (CABG) of the infarct-related artery with dobutamine Cup to 40 mu g/kg per minute) stress echocardiography before and 3 months after CABG. Ischemia was defined as new or worsened wall motion abnormalities. Functio nal recovery was defined as a reduction of regional wall motion score of 1 or more in 2 or more segments from the pre-CABG to post-CABG resting echoca rdiogram with the use of the 16-segment/5-grade score model. STE (greater t han or equal to 0.1 mV J-point elevation lasting 80 ms in greater than or e qual to 2 Q leads) occurred in 20 (57%) patients. There was no significant difference between patients with and those without STE before CABG with reg ard to the prevalence of peri-infarction ischemia (85% vs 80%) or index of improvement of regional function after CABG (0.26 +/- 0.26 vs 0.29 +/- 0.33 ). STE was reinduced to the same level in 4 patients after CABG, whereas 16 patients showed absent reinduction (8 patients) or reduced level (8 patien ts) of STE. Functional changes associated with absent reinduction or less S TE after CABG were absence of reinduction of regional ischemia in 13 patien ts, improvement of resting regional function in 5 patients, and resection o f scarred segments in 4 patients. Among the 4 patients with persistent dobu tamine-induced STE, 1 patient had persistent ischemia and 2 showed worsenin g of resting regional function. Although dobutamine-induced STE in patients with old Q-wave infarction referred for CABG cannot identify patients with a higher prevalence of ischemia, the lack of reinduction of this pattern a fter CABG correlates with absent reinduction of ischemia in most of patient s.