STRESS RADIONUCLIDE STUDIES AFTER ACUTE MYOCARDIAL-INFARCTION - CHANGES WITH REVASCULARIZATION

Background. Successful revascularization of ischemic asynergic myocard ium should be followed by improvement in contractile function, However , a clear improvement is not always observed, Assessment of contractil e reserve may allow a better evaluation of procedural results. Methods and Results, To assess the changes in global and regional left ventri cular 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 r edistribution (observed in stress-rest-reinjection thallium single-pho ton emission computed tomography). Regional EF was defined in the asyn ergic region at rest, which corresponded to the infarct plus periinfar ct areas, Both thallium single-photon emission computed tomography and equilibrium radionuclide angiography were performed at rest and durin g stress,vith dobutamine, up to a maximal dose of 40 mu g/kg/min. The same studies were repeated 8 +/- 6 months after successful revasculari zation (nine coronary angioplasties and seven bypass procedures), Afte r intervention, the thallium defect score decreased significantly at r est and during stress, Global EP changed from 45% +/- 10% to 47% +/- 1 1% (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 c aused by periinfarct ischemia, there can be an increase in regional bu t not global EF at rest after revascularization, However both paramete rs improve at peak dobutamine dose, This indicates an improvement in c ontractile reserve.