Myocardial viability assessment by PET: (82)Rb defect washout does not predict the results of metabolic-perfusion mismatch.

PET is a sensitive technique for the identification of viable myocardial tissue in patients with coronary disease. Metabolic assessment with 18F-FDG is considered the gold standard for assessment of viability before surgical revascularization. Prior research has suggested that viability may be assessed with washout of 82Rb between early and late resting images. Our objective was to determine whether assessment of myocardial viability with 82Rb washout is reliable when compared with PET using 18F-FDG. Methods: We performed PET for 194 patients referred for PET 18F-FDG/82Rb to assess viability for clinical indications. We included 151 patients with resting defects >10% of the left ventricle (LV) (n = 159 defects). Patients with smaller resting 82Rb defects ( 125% of 82Rb uptake in the 82Rb defect). Evidence of viability with 82Rb was assessed by the presence of (i) severity: 82Rb counts in the defect >50% of 82Rb in the normal zone of the resting PET images; (ii) washout: decrease of 82Rb counts in the defect from early to late resting 82Rb images