Stress radionuclide studies after acute myocardial infarction: changes with revascularization.

BACKGROUND

Successful revascularization of ischemic asynergic myocardium should be followed by improvement in contractile function. However, a clear improvement is not always observed. Assessment of contractile reserve may allow a better evaluation of procedural results.

METHODS AND RESULTS

To assess the changes in global and regional left ventricular ejection fraction (EF), as well as the contractile reserve after revascularization, equilibrium radionuclide angiography was performed in 16 patients with acute myocardial infarction who had periinfarct redistribution (observed in stress-rest-reinjection thallium single-photon emission computed tomography). Regional EF was defined in the asynergic region at rest, which corresponded to the infarct plus periinfarct areas. Both thallium single-photon emission computed tomography and equilibrium radionuclide angiography were performed at rest and during stress with dobutamine, up to a maximal dose of 40 micrograms/kg/min. The same studies were repeated 8 +/- 6 months after successful revascularization (nine coronary angioplasties and seven bypass procedures). After intervention, the thallium defect score decreased significantly at rest and during stress. Global EF changed from 45% +/- 10% to 47% +/- 11% (difference not significant) at rest and from 49% +/- 12% to 63% +/- 13% (p = 0.0001) at peak stress. Regional EF changed from 27% +/- 8% to 35% +/- 18% (p = 0.03) at rest and from 29% +/- 10% to 56% +/- 21% (p = 0.0001) at peak stress.

CONCLUSIONS

In patients with asynergy caused by periinfarct ischemia, there can be an increase in regional but not global EF at rest after revascularization. However, both parameters improve at peak dobutamine dose. This indicates an improvement in contractile reserve.