Myocardial scintigraphy in acute myocardial infarction treated with systemic thrombolysis: how far are we from obtaining reliable information for rescue PTCA?
All noninvasive tests have an unsatisfactory accuracy in assessing patency of the infarct related vessel after systemic thrombolysis. In large infarctions, the prompt knowledge of the amount of jeopardized myocardium, as well as the eventual success of thrombolysis on the culprit lesion are major clinical needs in the subsequent decision making process, including the indication to rescue PTCA. Several reasons preclude a meaningful use of thallium scintigraphy in this setting: the most important one is the need to perform pre-thrombolytic images before the administration of the active agent, implying a delay in the administration of thrombolysis that is clinically not acceptable. SestaMIBI perfusion scintigraphy at rest seems more suitable in this regard. SestaMIBI practically does not redistribute in the myocardium, and this implies that after an administration at admission in the CCU, the pre-thrombolysis images can be acquired later, without any interference with the therapeutic schedule. The estimate of myocardial salvage can be obtained by the comparison of the perfusion pattern derived from a later sestaMIBI injection with the pre-lysis images. Both planar and tomographic reconstructions have satisfactory positive and negative predictive accuracy for the patency of the culprit vessel. Difficulties are related with the necessity of having this information timely; we describe a few protocols, appeared in the literature, that might contribute in solving such problems. SestaMIBI imaging in patients with acute myocardial infarction should be encouraged and extended, given its potential to represent one of the best tool to judge the amount of jeopardized myocardium, the obtained salvage, and to guide the decision making after systemic thrombolysis.