Myocardial viability assessment after acute myocardial infarction: low-dose dobutamine echocardiography versus rest-redistribution thallium-201 SPECT.

BACKGROUND: The presence of tissue viability is of great importance in the prognostic work-up of patients recovering from acute myocardial infarction. However, uncertainty still exists concerning the optimal tool for its assessment. The present study was undertaken in order to compare low-dose dobutamine echocardiography and rest-redistribution thallium SPECT for predicting late improvement of regional left ventricular function after acute myocardial infarction. METHODS: Fifteen patients undergoing coronary angiography, low-dose dobutamine echocardiography and rest-redistribution thallium SPECT after thrombolyzed anterior acute myocardial infarction were studied. A 3 month follow-up echocardiogram was performed in all patients and 9 underwent coronary revascularization. RESULTS: A significant (> or = 70%) residual stenosis of the infarct-related artery was present in 14 patients, whilst a total occlusion was observed in 1. At 3 month follow-up, 41% of the dyssynergic segments improved. The sensitivity, specificity and accuracy for late wall motion improvement was 61, 89 and 77% for low-dose dobutamine echocardiography and, respectively, 76, 45 and 58% for rest-redistribution thallium SPECT. Tissue viability was detected in 65 and 31% of dyssynergic segments by rest-redistribution thallium SPECT and low-dose dobutamine echocardiography, respectively (p < 0.001). The agreement between the two techniques was 48%. CONCLUSIONS: Low-dose dobutamine echocardiography is more accurate than rest-redistribution thallium SPECT for predicting 3 month wall motion improvement in patients with acute anterior myocardial infarction, mainly due to its significantly better specificity.

Early assessment of viable myocardium after acute myocardial infarction by low-dose echo-dobutamine.

BACKGROUND: The aim of the study was to evaluate the usefulness of low-dose dobutamine echocardiographic testing performed within 48 hours from anterior AMI in order to identify the extent of viable myocardium and predict its functional outcome. The early echo-dobutamine test was also compared with a predischarge test in order to evaluate the effects of different timing on the accuracy of the test. METHODS: Nineteen consecutive patients, aged 54 +/- 11 years, with a first anterior AMI entered the study. All patients underwent a low-dose dobutamine echocardiographic test within 48 hours from hospital admission and at predischarge. In all the patients, a rest follow-up echocardiogram was performed three months after hospital discharge. Eleven patients underwent a revascularization procedure (7 underwent PTCA and 4 CABG). RESULTS: Of the 159 dyssynergic segments, 26% improved spontaneously at predischarge and 51% improved at the three-month follow-up. Of the 145 predischarge dyssynergic segments, 38% improved at three months. Considering the results on a segmental basis, early low-dose dobutamine echocardiography showed a sensitivity of 52%, a specificity of 87%, a positive predictive value of 81%, a negative predictive value of 64% and a diagnostic accuracy of 69% for wall-motion improvement at three months. The predischarge test showed very similar values. A slight enhancement of the sensitivity of both tests was observed considering the akinetic segments only. Finally, considering the amount of segmental reversible dysfunction inside the infarct area in the single patients, early low-dose dobutamine echocardiography showed a sensitivity of 86% and a specificity of 80%. CONCLUSIONS: Our results indicate that: 1) recovery of regional wall motion after AMI is slow and progressive, with substantial improvement ensuing within the first days after infarction; 2) considering results on a segmental basis, low-dose dobutamine echocardiography performed within 48 hours of AMI shows a high specificity but a low sensitivity for late recovery of regional function, although it gave information similar to what was obtained performing the test at predischarge; 3) the efficiency of test can be improved by considering the amount of reversible segmental dysfunction inside the infarct area in the single patients.