Objective: The aim of the study was to evaluate the diagnostic yield of 99m-Technetium-methoxy-isobutyl-isonitrile (MIBI) SPET for identification of individual coronary artery disease and in the prediction of multivessel involvement.
Methods: Stress/rest myocardial SPET and coronary arteriography were evaluated in 231 consecutive patients (age 58 +/- 10 years, 26% women) without prior myocardial infarction. 149 patients had coronary narrowing > 50%: 104 with multivessel disease and 45 with one vessel disease. Tomographic stress defect score was obtained by semiquantitative analysis (maximal score 65). Univariate and multivariate analysis was performed to identify discriminant parameters between one vessel and multivessel patients.
Results: The sensitivity and specificity for the identification of individual artery disease was 74% and 85% for left anterior descending artery, 79% and 85% for right coronary and 45% and 96% for circumflex artery. In the prediction of multivessel involvement the sensitivity was 65%, specificity 87%, positive predictive value 81% and negative predictive value 76%. In the bivariate analysis, four parameters differed significantly between one vessel and multivessel disease patients: ST downslope > 1 mm (p = 0.01), ST downslope/heart rate corrected (p = 0.005), reversible defects in two or more regions (p = 0.009) and SPET score (p = 0.002). In the multivariate analysis the probability of multivessel disease was 90% when ST depression > 1 mm and SPET score > 20 were associated and the probability was lowered to 16% when these criteria were not present.
Conclusion: Myocardial SPET with MIBI offers an accurate localization of individual coronary artery disease, mainly in left anterior descending artery and right coronary artery lesions. Combined evaluation of ST depression and extension of myocardial stress defects improved prediction of multivessel involvement.