Evaluating Microvascular Obstruction After Acute Myocardial Infarction Using Cardiac Magnetic Resonance Imaging and 201-Thallium and 99m-Technetium Pyrophosphate Scintigraphy

Background: Few studies have compared the ability of cardiac magnetic resonance (CMR) with that of scintigraphy using 201-thallium (201-Tl) and 99m-technetium pyrophosphate (99m-Tc PYP) to evaluate microvascular obstructions (MOs). In the present study the relationship between the scintigraphic and CMR characteristics of MOs after acute myocardial infarction (MI) was examined. Methods and Results: The 14 patients (age 69+/-8 years, 11 males) underwent 201-Tl/99m-Tc PYP SPECT 7+/-3 days, initial CMR 16+/-12 days, and follow-up CMR 193+/-20 days after a reperfused first acute MI. Each image was analyzed using a 17-segment model. Segmental extent of delayed enhancement (DE), wall motion (WM) and degree of 201-Tl uptake were scored in 238 segments Of 91 MI segments, MO was recognized in 22 (25%) segments on CMR WM was significantly better in proportion to 201-TI uptake (P=0.01) in MO segments. All 8 MO segments with WM improvement at follow-up had 99m-Tc PYP uptake, although only 3(21%) of 14 MO segments that did not show WM improvement at follow-up had 99m-Tc PYP uptake (P=0.001). Conclusions: 99m-Tc PYP and 201-TI scintigraphy have the potential to predict WM status and improvement of the MO region after reperfused acute MI. (Circ J 2010; 74: 2633-2640)