Significance of transient ST-T segment changes during dobutamine testing in Q wave myocardial infarction.
OBJECTIVE
We evaluated dobutamine stress electrocardiography for detecting potentially reversible contractile dysfunction or residual ischemia in the infarct-related area.


BACKGROUND
ST-T segment changes in pathologic Q wave leads during stress testing may reflect contractile reserve, inducible ischemia or passive mechanical stretching. Dobutamine echocardiography allows detection of contractile reserve at low doses and inducible ischemia at high doses.


METHODS
We used low (5 to 10 microg/kg body weight per min) and high doses (20 to 40 microg/kg per min) of dobutamine in 49 patients with a previous Q wave myocardial infarction and analyzed the relation between ST-T segment changes in pathologic Q wave leads and regional contraction.


RESULTS
At low dose dobutamine, regional contraction improved in the infarct-related area in 23 patients. New or further ST segment elevation and pseudonormalization of negative T waves developed at low doses more frequently in patients with than without contractile reserve (both p < 0.001), giving a sensitivity of 43.5% and 60.9% and a specificity of 100% and 96.2%, respectively. At high dose dobutamine (43 patients), new or further ST segment elevation and pseudonormalization of negative T waves, occurring beyond those observed at low doses, had a low predictive accuracy for contractile reserve (sensitivity of 9.5% and 14.3% and specificity of 68.2% and 81.8%, respectively). Pseudonormalization of negative T waves at high dose dobutamine was 100% specific (but only 25% sensitive) for homozonal ischemia.


CONCLUSIONS
ST segment elevation or pseudonormalization of negative T waves, or both, is indicative of contractile reserve in the infarct-related area when either develops at low dose dobutamine, but may be associated with worsening or no change in contractile function at high doses.
Lombardo
A
A
Institute of Cardiology, Catholic University Sacro Cuore, Rome, Italy.
Loperfido
F
F
Pennestri
F
F
Rossi
E
E
Patrizi
R
R
Cristinziani
G
G
Catapano
G
G
Maseri
A
A
D000368:Aged; D004280:Dobutamine / Q000008:administration & dosage; D004452:Echocardiography / Q000187:drug effects; D004562:Electrocardiography / Q000187:drug effects; D005080:Exercise Test / Q000187:drug effects*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009200:Myocardial Contraction / Q000187:drug effects*; D009203:Myocardial Infarction / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D012680:Sensitivity and Specificity; D013566:Sympathomimetics / Q000008:administration & dosage
D013566:Sympathomimetics; D004280:Dobutamine