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- induced ST-segment elevation (STE) in Q leads. However, the effect of revascularization on the induction of STE was not investigated. We studied 35 patients with old Q-wave myocardial infarction who underwent coronary artery bypass grafting (CABG) of the infarct-related artery with dobutamine (up to 40 μg/kg per minute) stress echocardiography before and 3 months after CABG. Ischemia was defined as new or worsened wall motion abnormalities. Functional 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 echocardiogram with the use of the 16-segment/5-grade score model. STE (≥0.1 mV J-point elevation lasting 80 ms in ≥2 Q leads) occurred in 20 (57%) patients. There was no significant difference between patients with and those without STE before CABG with regard 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 patients) of STE. Functional changes associated with absent reinduction or less STE after CABG were absence of reinduction of regional ischemia in 13 patients, improvement of resting regional function in 5 patients, and resection of scarred segments in 4 patients. Among the 4 patients with persistent dobutamine-induced STE, 1 patient had persistent ischemia and 2 showed worsening 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 after CABG correlates with absent reinduction of ischemia in most of patients.

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