[Cardiac radionuclide scanning with 99mTc-MIBI-SPECT in acute myocardial infarction]

Several studies point out the importance of what is called rescue angioplasty or fibrinolysis (FB) when thrombolysis has been ineffective in acute myocardial infaction (AMI). Therefore, it is necessary to make use of new methods to asses reperfusion and to safely establish that such a treatment has not been effective. We present a work which is based on the assessment of patients with acute coronary heart disease: AMI patients treated with FB (N = 48), without FB (N = 15), unstable angina (N = 9); after determining cardiac imaging gammagraphies 99mTc-isonitrile-single-photon emission computed tomography (MIBI-SPECT) pre and post treatment, to assess myocardium at risk (MR), salvage (MS) and the existence or not of gammagraphic reperfusion. Unstable angina patients show a myocardial perfusion that is similar to AMI patients. However, in the case of unstable angina, perfusion is practically of a 100% 48 hours later, having almost completely saved the myocardium at risk (MS/MR = 81.5% +/- 27.7%), and with a non-existent residual myocardium (3.2% +/- 5.8%). In AMI patients treated with FB the salvage myocardium was higher [8.3 vs 3.0; p < 0.05). Considering that an improvement in perfusion defect (MS/MR)] higher than 30% can be viewed as an effective reperfusion, we can see that all the patients with unstable angina show reperfusion, the percentage in the AMI group treated with FB being 45.8%, and the percentage in the AMI group under conventional treatment being just 6.7%. Gammagraphy with 99mTc-MIBI-SPECT at admission allowed assessing regional perfusion in AMI patients during the early stage of their evolution. With a second exploration we could determine the amount of salvage myocardium and the existence of secondary reperfusion to FB treatment.