Objective: ST-segment elevation is frequently induced by dobutamine in patients with a recent myocardial infarction and may represent dyskinesia of the infarcted region or myocardial viability and ischaemia. Revascularization of the infarct-related artery may abolish myocardial ischaemia, and thus represents a useful tool to verify the significance of this finding. The aim of this study was to assess the relation between ST-segment elevation and wall motion response during dobutamine echo stress test and to evaluate the effect of coronary revascularization with percutaneous coronary angioplasty of the infarct-related artery on stress test results.
Methods and results: Twenty-two patients (17 men; mean age 58+/-12 years) with a first acute myocardial infarction (5 anterior (23%) and 17 (77%) inferior) who showed ST-segment elevation during a dobutamine echo stress test performed early (7+/-5 days) after the acute event where included in the analysis. All patients underwent coronary arteriography followed by percutaneous revascularization with coronary angioplasty or atherectomy with or without stenting of the culprit lesion and a second dobutamine echo stress test at a mean of 40+/-20 days after revascularization. The minimal lumen diameter increased from 0.63+/-0.36 to 3+/-0.44 mm and % diameter stenosis decreased from 80+/-11 to 12+/-7 after revascularization. At baseline evaluation there were 62 normal moving segments (34%), 57 (32%) akinetic and 62 (34%) hypokinetic segments within the area at risk. Maximal ST-segment shift changed from a basal mean value of 0.41+/-0.6 to a peak value of 2.15+/-0.9 mm; angina developed in 6/22 patients (22%). A biphasic response to dobutamine indicative of myocardial ischaemia within the infarcted area was observed in 20/22 patients (91%) and in 54/74 (73%) segments showing wall motion abnormalities. After revascularization of the infarct-related artery 78 (43%) segments were considered to be normal, 46 (25%) akinetic and 57 (32%) hypokinetic. Dobutamine-induced ST-segment elevation in 6/22 cases (27%), but the amount of ST-segment shift at peak stress was significantly reduced (from 2.15+/-0.9 to 0.30+/-0.5 mm) and angina was present in 1 patient only (5%) despite a significant increase of double product compared to the pre-revascularization test (from 17,348+/-3536 to 21,005+/-4105, p < 0.003). At echocardiographic analysis, ischaemia involved only 4 segments (2%), 3 of them showing the persistence of a biphasic response to dobutamine.
Conclusions: In patients with a recent myocardial infarction and no baseline dyskinesia dobutamine-induced ST-segment elevation in the infarct-related leads is usually associated with a biphasic response of wall motion within the infarcted region and may be considered an ancillary sign of myocardial ischaemia because it is abolished in the great majority of cases by successful revascularization of the infarct-related artery.