Assessment of myocardial, viability with technetium-99m isonitrile and thallium-201. Results of a Spanish multicenter trial

Background. Regions with severe impaired function in patients with chronic coronary artery disease may have improved contractility after coronary revascularization procedures. This multicentric trial was undertaken to assess the yield of rest technetium-99-isobutil-isonitrile (Tc-99m-MIBI) and thallium-201 (Tl-201) single photon emission tomography in the prediction of functional recovery. Patients and methods. 116 patients (mean age 59 +/- 10, 12 women) with severe impairment of regional contractility who underwent coronary artery bypass grafting (n = 84) or percutaneous coronary angioplasty (n = 32) were studied. Rest Tc-99m-MIBI and Tl-201 Single photon emission tomography and three views radionuclide ventriculography were performed before and 3-6 months after revascularization. Regional contractility and radiotracer uptake were evaluated in 9 left ventricular segments. Results. No change was observed in mean left ventricular ejection fraction pre- and post-revascularization (41.1% +/- 14.5% vs 41.8% +/- 15.7%). 28% of patients increased > 5 ejection fraction units, 50% did not change and in 22% of patients ejection fraction decreased >5 units. Only 34.4% of segments with severe impairment of regional contractility improved after revascularization. Using 30% uptake as the lower limit of myocardial viability, sensitivity of 79% and specificity of 40% for Tc-99m-MIBI and 80% and 46% respectively for Tl-201 were obtained. There was a significantly inverse relation (p = 0.04) between the number of segments with less than 30% of radiotracer uptake and the probability of increasing ejection fraction after revascularization. Conclusions. No differences were observed in the sensitivity or specificity of Tc-99m-MIBI and Tl-201 single photon emission tomography in the prediction of functional recovery after revascularization in patients with coronary artery disease and severe impairment of regional contractility. The probability of increased ejection fraction after revascularization is inversely related to the extent of the regions with less than 30% of uptake.