Dobutamine-atropine stress echocardiography for reversible dysfunction during the first week after acute myocardial infarction: limitations and determinants of accuracy.
OBJECTIVE
We sought to compare the accuracy of biphasic and ischemic responses and sustained improvement for reversible dysfunction and to identify causes of false negative and false positive findings.


BACKGROUND
Previous studies have shown that low dose dobutamine echocardiography was accurate for detecting reversible dysfunction after acute myocardial infarction (MI) but did not determine whether accuracy was improved by peak dose findings or influenced by the test interval or clinical or angiographic factors.


METHODS
Dobutamine-atropine stress echocardiography (DASE) (baseline, low dose [5 and 10 microg/kg body weight per min] and peak dose) and coronary angiography were performed in 115 patients 2 to 7 days after MI (test interval). Segmental wall thickening was analyzed according to the 16-segment model. Sustained improvement and biphasic and ischemic responses included improved wall thickening at low and peak doses, improved wall thickening at the low dose with worsening at peak dose and no change in wall thickening at the low dose with worsening at peak dose, respectively. Follow-up echocardiography was performed at 4 to 8 weeks, and reversible dysfunction was defined as improved wall thickening.


RESULTS
Wall thickening improved at follow-up in 305 (44%) of 688 dysfunctional segments. The test interval was 2 days in 16 patients, 3 days in 24, 4 days in 24, 5 days in 12, 6 days in 16 and 7 days in 23. No change at low and peak doses accurately predicted fixed dysfunction (318 [88%] of 360 segments), especially in akinetic and dyskinetic segments (276 [91%] of 303), irrespective of the test interval or clinical and angiographic factors. Ischemic segmental responses also predicted fixed dysfunction (63% [12 of 19 patients]), especially in medically treated compared with revascularized patients (100% [8 of 8] vs. 36% [4 of 11], p = 0.013). Both biphasic responses and sustained improvement (77% [179 of 231 segments] vs. 87% [84 of 97], p = 0.082) were highly predictive of reversible dysfunction, especially in akinetic segments, irrespective of the test interval or clinical and angiographic factors. The only limitation was reduced accuracy (77% [177 of 222 segments], p < 0.001) due to false positive results (16%) in hypokinetic segments.


CONCLUSIONS
No change and ischemic responses during DASE were specific for fixed dysfunction. Improved wall thickening at the low dose, irrespective of changes at peak dose, was highly predictive of reversible dysfunction. Accuracy was only limited by false positive results in hypokinetic segments and not by the test interval or clinical or angiographic factors.
Smart
S
S
Department of Medicine, Medical College of Wisconsin and Zablocki Veterans Administration Medical Center, Milwaukee 53226, USA. ssmart@post.its.mcw.edu
Wynsen
J
J
Sagar
K
K
D001285:Atropine; D017023:Coronary Angiography; D004280:Dobutamine; D004452:Echocardiography / Q000379:methods / Q000706:statistics & numerical data; D005188:False Negative Reactions; D005189:False Positive Reactions; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D009200:Myocardial Contraction; D009203:Myocardial Infarction / Q000000981:diagnostic imaging* / Q000503:physiopathology; D017202:Myocardial Ischemia / Q000000981:diagnostic imaging; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D013997:Time Factors
D004280:Dobutamine; D001285:Atropine