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

Objective To study the impact of detection of viability of myocardium in as ymptomatic patients early (3-10 days) after Q-wave myocardial infarction on segmental recovery of left ventricular function after elective revasculari zation. Methods Patients were studied with low-dose dobutamine echocardiography (LD DE) and single photon-emission computed tomography with Tc-99m sestamibi an d [F-18]-fluorodeoxyglucose (FDG) imaging. Viability of myocardium was defi ned as detection of improvement in segmental thickening of left ventricle b y LDDE (versus baseline echocardiographic data), uptake of Tc-99m sestamibi > 50% of maximum counts, uptake of [F-18]-FDG > 50% Of maximum normal, com bined uptake of Tc-99m sestamibi or [F-18]-FDG > 50% of normal maximum, upt ake of [F-18]-FDG > 50% or mismatched pattern (uptake of [18F]-FDG greater than that of Tc-99m sestamibi). Functional recovery was defined as improvem ent of segmental thickening of left ventricle detected at follow-up 8 weeks after infarction (versus baseline resting echocardiographic data). Interpr etation of the tests was blinded with respect to the angiographic data and the results of the alternative method. Results In total 18 patients with 133 left-ventricle segments with abnormal contractile function at baseline were analysed; 29% were hypocontractile a nd 71% were noncontractile. Examination with LDDE showed that 18% of the se gments had normal contractility and 26% were hypocontractile; the respectiv e percentages were 29 and 28% according to follow-up resting echocardiograp hy. Radionuclide tests for viability of myocardium gave positive results in 57% (uptake of [F-18]-FDG > 50%) and 62% (uptake of Tc-99m sestamibi > 50% ) of cases. With respect to segmental analysis, there was a 25-27% positive concordance, a 24-27% negative concordance, and a 48-50% discordance betwe en the LDDE and the radionuclide definitions of viability of myocardium. Ad ditionally, there was no significant difference among sensitivities and spe cificities for the definitions of viability. The sensitivity was 69% for th e uptake of Tc-99m sestamibi > 50% criterion, and the highest specificity w as 66% for the LDDE. Incorporation of imaging with [F-18]-FDG into the anal ysis yielded a marginally higher sensitivity of 71% for the criterion of up take of [F-18]-FDG or Tc-99m sestamibi > 50%, versus imaging with the Tc-99 m sestamibi alone. Conclusion LDDE was more specific and radionuclide imaging more sensitive f or detection of viability of myocardium in asymptomatic patients early afte r infarction. Possibly defective myocardial metabolization of glucose in th e period early after infarction and the specific LDDE protocol applied acco unt for the limited benefit of these studies in terms of facilitating predi ction of segmental functional recovery after revascularization in this clin ical setting. Coron Artery Dis 11:409-414 (C) 2000 Lippincott Williams & Wi lkins.