WESTPORT, CT (Reuters Health) – Dobutamine-induced changes in QT dispersion and wall motion have predictive value after acute myocardial infarction (AMI), according to a report in the November 1st issue of the American Journal of Cardiology.
In the same issue, Italian researchers announce that dobutamine stress echocardiography is an effective diagnostic tool for predicting the anatomic status of the infarct-related artery.
In the first study, Dr. Luc A. Pierard and colleagues from the University of Liege, Belgium sought to correlate dobutamine-induced changes in QT dispersion with wall motion responses in 78 patients with a first AMI.
Whereas dobutamine brought increased QT dispersion in patients with viable myocardium and/or ischemia, the authors report, no change in QT dispersion was seen in patients with persistent akinesia.
Among patients with an ischemic response to dobutamine, QT dispersion at peak stress was significantly longer in patients with myocardium at risk (112 ms) than in patients without jeopardized myocardium (85 ms) (p = 0.00002), the report indicates.
"Thus," the authors conclude, "measurement of QT dispersion changes during graded dobutamine infusion may be useful for stratifying risk after AMI."
In the second study, Dr. Riccardo Bigi from Campo di Marte Hospital in Lucca, Italy and colleagues aimed to correlate individual patterns of dobutamine stress echocardiography (DSE) to the anatomic status of the infarct-related artery in 159 patients with AMI.
A biphasic response–improvement with a low dose and deterioration with a high dose of dobutamine–was the only significant predictor of severe stenosis, the authors report, proving better than 11 other clinical and echocardiographic variables.
Patients with a biphasic pattern had significantly higher jeopardy scores (reflecting larger areas of myocardium at risk) than did patients with worsening patterns (deterioration at all doses), sustained improvement, or no change.
"The biphasic response to DSE can indicate a severe lesion of the infarct-related artery in a patient at increased risk for subsequent cardiac events, who may be amenable to therapeutic intervention," the researchers conclude. "In particular, this should be helpful in patients with a large dyssynergic area when they are at rest, where information on the potential benefit from revascularization is crucial."
Am J Cardiol 2001;88:939-948.
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