Comparison of low-dose dobutamine echocardiography and thallium-201 reinjection for the determination of myocardial viability in the early post myocardial infarction period.

OBJECTIVE

Determination of viability in the infarction zone in the early post Ml period is an important parameter in clinical decision making.

METHODS

In an attempt to compare the places of low-dose dobutamine echocardiography (LDDE) and thallium-201 reinjection SPECT (TI-SPECT) in the determination of viability in dyssynergic myocardial segments, 17 patients (mean age: 54.6 +/- 12.8 years, 16 male, 1 female) with a recent myocardial infarction and an uneventful early clinical course underwent both tests within 5-13 days of infarction. The 16-segment model was utilised to evaluate the left ventricular wall motion and each segment was graded as 1) normokinetic, 2) hypokinetic, 3) akinetic and 4) dyskinetic or aneurysmal on a 4-scale basis. A dyssynergic segment of myocardium was considered to be viable by LDDE if it showed an improvement in wall motion of at least one grade with low-dose dobutamine infusion (10 microg/kg/min). On the other hand, mild to moderate (< 50%) fixed perfusion defects and reversible (at least a 10% improvement in perfusion on either redistribution or reinjection images) severe (50% or more) perfusion defects were considered positive for viability by TI-SPECT.

RESULTS

Of the 76 segments with resting dyssynergy (10 dyskinetic/aneurysmal, 33 akinetic, 33 hypokinetic), 51 (67%) were shown to be viable by LDDE and 61 (80%) by TI-SPECT. There was an agreement of 76% (p = 0.03, K = 0.63) between the two methods.

CONCLUSION

This study disclosed a moderate degree of agreement between LDDE and TI-SPECT for the determination of viability in dyssynergic myocardial segments in the early post-myocardial infarction period.