Evaluation of myocardial viability in asymptomatic patients early after infarction with perfusion/metabolism single-photon-emission computed tomographic imaging and dobutamine echocardiography

The predictive value of 201Tl rest-redistribution and 18F-fluorodeoxyglucose SPECT for wall motion recovery after recent reperfused myocardial infarction

201Tl and 18F-FDG are useful for acute myocardial infarction (MI) assessment. The goal of this study was to compare their predictive value for wall motion recovery in the culprit area after a recent reperfused MI using SPECT technique.

METHODS

Forty-one patients (mean age: 56 +/- 12 years) were included, 81% of them male; all were studied within 1-24 days post MI. They underwent angioplasty in 27 cases (12 primary); bypass grafting in 10 cases and successful thrombolysis in 4. SPECT 201Tl injected at rest and redistribution (R-R) and also 18F-FDG, were performed on different days. Processed tomograms were interpreted blinded to clinical or angiographic data. Segmental wall motion assessed with echocardiography at baseline was compared with the 3 month follow up.

RESULTS

Sensitivity [Confidence Interval] for 201Tl R-R was 74.6% [60.5-84.5], for FDG it was 82.1% [70.8-90.4]; specificities were 73% [64.3-80.5] and 54.8% [45.6-63.7], respectively. 18F-FDG tended to be more sensitive than 201Tl R-R, but the latter was more specific (p < 0.0004). Both 201Tl RR and 18F-FDG presented high negative predictive value (p: ns).

CONCLUSION

In recent MI, SPECT 201Tl R-R is a valuable and widely available technique for viability detection, with similar sensitivity and significant better specificity than SPECT 18F-FDG.

An assessment of wall motion, perfusion and glucose metabolism in recent myocardial infarction: a comparison in patients with and without revascularization

The aim of this study was to compare the extent and severity of wall motion abnormalities, perfusion and glucose metabolism, in recent myocardial infarction in patients with and without revascularization. Forty-nine patients were studied (82% men; mean age 58 years) by using echocardiography, 201Tl single photon emission computed tomography (SPECT) rest and redistribution, and 2-[18F]fluoro-2-deoxy-D-glucose (18F-FDG) SPECT at a mean of 9.2 days (range, 1-24 days) after myocardial infarction. Twenty-seven of the 49 patients underwent revascularization while the other 22 received medical therapy before echocardiography and studies using radionuclides. A contrast angiogram was obtained for each patient. A follow-up echocardiogram at 3 months was obtained for 44 patients. Images were read blindly, using a 17 segment model, with semi-quantitative analysis. In the whole group, the extent of hypokinesia was 15%+/-14 (mean+/-SD); the extent of mild defects was determined as 5%+/-6 by using 201Tl at rest, 6%+/-9 by using 201Tl redistribution, and 4%+/-6 by using 18F-FDG (P<0.0005, echocardiogram/radionuclides). Echocardiography showed that the extent of akinesia-dyskinesia was 16%+/-18 in revascularized patients and 28%+/-18 in non-revascularized patients (P=0.017). With regard to moderate and severe defects, 201Tl rest showed 19%+/-16 and 28%+/-17, respectively (P=0.047); 201Tl redistribution 17%+/-15 and 26%+/-15, respectively (P=0.043); and 18F-FDG 17%+/-13 and 24%+/-15, respectively (NS). In echocardiography, the extent of hypokinetic segments decreased from 16%+/-15 at baseline to 10%+/-11 at 3 months (P=0.045), in revascularized patients. It is concluded that, in recent myocardial infarction, hypokinesia extent on echocardiogram is greater than mild perfusion or metabolic defect extent, reflecting stunning and so the use of radionuclide techniques appear more accurate for defining the extent of myocardial infarction. Non-revascularized patients showed a significantly greater extent of akinesia-dyskinesia and moderate-severe perfusion defects than did revascularized patients, which can be considered a result of therapy. It is suggested that 201Tl rest perfusion be used for the assessment of myocardial infarction soon after revascularization.