Comparison of Dobutamine Echocardiography and Thallium Scan in Assessment of Viable Myocardium After Acute Myocardial Infarction

Lee, Keun; Kang, Duk Hyun; Song, Jae Kwan; Lee, Cheol Whan; Choi, Kee Joon; Hong, Myeong Ki; Kim, Jae Joong; Park, Seong Wook; Park, Jong Hun; Park, Seung Jung

Abstract

BACKGROUND
It is clinically important to evaluate myocardial viability after acute myocardial infarction. There are several methods like dobutamine stress echocardiography (DSE) and thallium scan to identify viable myocardium. Thallium SPECT assesses cellular integrity and dobutamine stress echocardiography assesses contractile reserve of myocardium.
METHODS
Between March and August 1995, 30 consecutive patients (27 men and 3 women; mean age 52+/-12years) within 3 weeks after acute myocardial infarction were admitted to Asan Medical Center. Each underwent two-dimensional echocardiography before and during dobutamine infusion 8.6+/-6.5 days after acute myocardial infarction and thallium scan with rest-redistribution or stress-redistribution-reinjection protocol 8.1+/-6.4 days after acute myocardial infarction. Viability myocardium was considered if there were improvement in regional wall motion during dobutamine infusion (5, 10mg/kg/min for 5min and 20, 30mg/kg/min for 3min), With thallium SPECT, myocardial viability was considered if regional wall motion was normal, if perfusion defect, were either completely or partial mildly reversible, or if myocardial perfusion decreasedly or moderately and if irreversible perfusion was defect. Follow-up echocardiography was performed 3+/-1 months after acute myocardial infarction. Recovery of regional function was identified when follow-up echocardiography showed improvement of wall motion. We evaluated the accuracy of dobutamine stress echocardiography and thallium scan by concordant interpretation in acute and follow-up studies.
RESULTS
Among the enrolled 30 patients, 27 patients had Q-wave MI. Thrombolysis was performed in 17 patients (57%) and PTCA was done in 18 patients (60%). The location of myocardial infarction wall in 20 patients and the inferior and lateral wall in 10 patients. Dobutamine stress echocardiography was performed safely in 30 patients 8.6+/-6.5 days after acute myocardial infarction. Improved wall motion was apparent in 15 patients (50%) after follow-up echocardiography 3+/-1 months after acute myocardial infarction. The positive and negative predictive values of dobutamine stress echocardiography were 14/17 (82%) and 12/13 (92%), respectively. Thallium SPECT was done in 26 patients 8.1+/-6.4 days after acute myocardial infarction. Among these 26 patients, follow-up echocardiography showed improved wall motion in 12 patients. The positive and negative predictive values of thallium SPECT were 9/10 (90%) and 13/16 (80%), respectively. Positive dobutamine stress echocardiography (r=0.46, p=0.001), positive thallium SPECT (r=0.44, p=0.003), hypokinetic segments (p=0.01) and non-anterior MI (p=0.02) were associated with reversible postischemic dysfunction.
CONCLUSION
Dobutamine stress echocardiography (DSE) can be safely performed early after acute myocardial infarction. Both dobutamine stress echocardiography and thallium SPECT are reliable and complementary methods to diagnose viable myocardium.