EFFECT OF MYOCARDIAL VIABILITY ASSESSED BY TECHNETIUM-99M-SESTAMIBI SPECT AND FLUORINE-18-FDG PET ON CLINICAL OUTCOME IN CORONARY-ARTERY DISEASE

PET imaging of myocardial perfusion and metabolism identifies regional viability as well as patients at high risk for Mure cardiac events. T his study evaluated a combined ''hybrid'' imaging approach using Tc-99 m-sestamibi SPECT and [F-18]fluoro-2-deoxy-D-glucose (FDG) PET with re gard to reversibility of regional dysfunction and to patient clinical outcome during a 2-yr follow-up. Methods: In this study, 161 consecuti ve patients underwent baseline viability imaging. All had regional wal l motion (RWM) abnormalities and 88% had a history of previous myocard ial infarction. Regions were classified by semiquantitative analysis o f sestamibi and FDG uptake as normal, mild match, mismatch or scar. Fo r clinical outcome, patients were divided into three groups: predomina ntly scar tissue (Group A, n = 90), mild match (Group B, n = 26) and m ismatch (Group C, n = 45). Treatment was performed with the knowledge of nuclear results. Cardiac events during follow-up were defined as de ath, myocardial infarction, unstable angina requiring revascularizatio n, heart transplantation and survived resuscitation. Results: Patients were followed for 29 +/- 6 mo. Revascularization rate was 30% in Grou p A, 81% in Group B and 80% in Group C, whereas the other patients wer e treated by medication. Only Group C demonstrated a significant reduc tion of cardiac events after revascularization, whereas, particularly in Group A, revascularization did not influence the frequency of event s. Subjective assessment of angina pectoris and heart failure revealed more patients with improvement after revascularization as compared wi th conservative treatment. Of the 84 revascularized patients, 61 under went follow-up angiography at 5 +/- 2 mo with RWM analysis using the c enterline method. RWM improved only in mismatch regions from -2.2 +/- 1.0 s.d. to -1.0 +/- 1.4 s.d. (p < 0.01), whereas regions with a mild match or scar did not change. Conclusion: Nuclear imaging using Tc-99m -sestamibi SPECT and [F-18]FDG PET allows diagnosis of viability in re gions with reduced perfusion and function with prognostic implications for functional outcome as well as for identification of patients who benefit most from revascularization.