Dobutamine-Induced Myocardial Ischemia and ST-Segment Elevation in Collateral-Dependent Myocardium

In patients with obstructive coronary artery disease, electrocardiographic (ECG) ST-segment elevation (STE) is frequently seen during dobutamine stress echocardiography (DSE) in leads overlying previous transmural left ventricular (LV) myocardial infarction. The mechanism of occasional STE during DSE in LV region with inducible myocardial ischemia and no previous myocardial infarction has not been well delineated. We retrospectively identified 28 adults (age 51 to 83 years [69 ± 8]; 82% men) with STE (>1 mm at ≥80 ms after J point in ≥2 contiguous leads without pathologic Q waves) and inducible myocardial ischemia in the same territory during DSE. STE occurred in inferior (n = 16), inferolateral (n = 8), anterior (n = 1), lateral (n = 2), or anterolateral (n = 1) leads and was associated with ischemic symptoms in 17 patients (61%). Inducible LV wall motion abnormality developed in LV segments corresponding to ECG STE in all patients. Coronary arteriography (within 1 week of the index DSE) showed severe luminal narrowing in the major epicardial coronary artery supplying the region with DSE STE and ischemia (90% to 99% in 9 patients [32%] and 100% in 19 patients [68%]). The ischemic region was supplied by ipsilateral (n = 4 [14%]), contralateral (n = 21 [75%]), or both ipsilateral and contralateral (n = 3 [11%]) collateral branches. In conclusion, dobutamine-induced ECG STE in LV segments with normal baseline wall motion is a highly reliable marker of viable collateral-dependent myocardium.