IMPACT OF MYOCARDIAL VIABILITY AND CORONA RY REVASCULARIZATION ON CLINICAL OUTCOME AND PROGNOSIS - AN OBSERVATIONAL STUDY IN 161 PATIENTS WITH CORONARY-ARTERY DISEASE

One hundred and sixty-one consecutive patients (144 male, 57 +/- 9 yea rs) with stable coronary artery disease underwent nuclear imaging for assessment of myocardial viability using Tc-99m sestamibi single-photo n emission computed tomography (SPECT) and F-18 fluoro-deoxy-glucose ( FDG) positron emission tomography (PET). 88 % had a history of chronic myocardial infarction and all had angiographically proven regional wa ll motion (RWM) abnormalities in the distribution territory of a steno sed or occluded coronary artery. Patients were followed for 29 +/- 6 ( 22-44) months with 84/161 patients (52 %) receiving elective revascula rization by either bypass surgery or angioplasty. 61/84 patients under went follow-up angiography after 5 +/- 2 months for quantitative asses sment of RWM changes using serial analysis with the centerline method in 45 pts with technically suitable paired angiograms. Myocardial regi ons were classified according to semiquantitative analysis of regional sestamibi and FDG uptake as either normal, regions with evidence for maintained viability but no mismatch (''mild match''), regions with a perfusion/metabolism ''mismatch,'' or scar. RWM improved in ''mismatch '' regions from -2.2 +/- 1.0 SD to -1.0 +/- 1.4 SD (p < 0.01) compared to the mean of a normal reference population. In contrast, in regions with a ''mild match'' or those classified as scar, RWM analysis revea led no functional changes at follow-up. For the assessment of clinical outcome, patients were divided into three groups depending on the res ult of viability imaging. Those with predominantly scar tissue in the target region for viability assessment (group A, n = 90), those with a ''mild match'' (B, n = 26), and group C (n = 45) consisting of patien ts with a ''mismatch'' pattern. Subsequent treatment was not blinded t o nuclear imaging results and revascularization was performed in 30 % of group A (group A2), 81 % of group B, and 80 % of group C, while the other patients were treated medically only. Cardiac events during fol low-up were defined as cardiac death, myocardial infarction, unstable angina with subsequent revascularization, cardiac transplantation, and survived resuscitation without evidence for myocardial infarction. Gr oup C demonstrated a significant reduction of cardiac events from 22 % to 0 % following revascularization, whereas in group A coronary revas cularization did not influence the frequency of events. Subjective ass essment of angina pectoris and heart failure symptoms revealed more pa tients with improvement following revascularization as compared to tho se treated medically. Thus, combined nuclear imaging using sestamibi S PECT and FDG PET with quantitative tracer uptake analysis allows detec tion of absent or preserved myocardial viability in regions with reduc ed perfusion and function with prognostic implication for regional myo cardial functional outcome as well as for identification of patients w ho benefit most from coronary revascularization.