MYOCARDIAL TC-99M SESTAMIBI SINGLE-PHOTON EMISSION TOMOGRAPHY AS A PROGNOSTIC TOOL IN CORONARY-ARTERY DISEASE - MULTIVARIATE-ANALYSIS IN A LONG-TERM PROSPECTIVE-STUDY

To date several studies have evaluated the accuracy of thallium-201 my ocardial scan in risk stratification of coronary artery disease (CAD), while reports using technetium-99m methoxyisobutylisonitrile (MIBI), a tracer particularly suited to single-photon emission tomographic (SP ET) imaging, are lacking. To rectify this omission, a prospective stud y was started in 1988 and at present 176 consecutive, and thus unselec ted, patients have been enrolled. All of them have been submitted to s tress-rest MIBI SPET for the diagnosis or evaluation of CAD; 147 patie nts (121 males and 26 females, aged 53 +/- 9 years) have completed a s urveillance period of at least 36 months following the scintigraphic s tudy (range 36-60 months, mean 43). Sixty-one patients had a documente d previous myocardial infarction. The mean pretest likelihood of CAD w as 44% in the patients without prior infarction. The main anamnestic, clinical, EKG and scintigraphic findings were evaluated and statistica lly correlated with the incidence of ensuing cardiac events using both univariate (chi-square test) and multivariate analysis (logistic regr ession model). Twenty-nine patients suffered from a cardiac event duri ng the follow-up period (i.e. three cardiac deaths, six myocardial inf arctions and 20 cases of unstable angina). Statistical multivariate an alysis identified MIBI scan as the only highly significant and indepen dent prognostic predictor [P = 0.006, relative risk (RR) = 17.62]. In detail, the most important scintigraphic parameters were the presence of a reversible defect (P = 0.0089, RR = 5.11) and the extension of th e stress perfusion defect (P = 0.0255, RR = 3.27). The presence of typ ical angina proved to be a slightly significant predictor (P = 0.051, RR = 2.45), while no other examined parameter showed a significant cor relation with a bad prognosis. In conclusion, MIBI SPET can be conside red a useful tool in the risk stratification of CAD patients. The pres ence of a reversible perfusion defect or an extensive defect appears r esponsible for a clear increase in the probability of subsequent cardi ac events, thus indicating a more aggressive therapeutic approach to b e appropriate.