Positron emission tomography and dobutamine echocardiography for assessing viability in patients with moderate ventricular dysfunction

Both low-dose dobutamine echocardiography (DE) and ¹⁸Fluorodeoxy-glucose (FDG) positron emission tomography (PET) are used for the assessment of myocardial viability in patients (pts) with hibernating myocardium. Since the accuracy of these two methods could vary according to the severity of left ventricular (LV) dysfunction, in the present study we aimed to compare their predictive value (PV) only in pts with moderate impairment of LV function. DE (5 and 10 μg/kg/min) and FDG PET during euglycaemic hyperinsulinaemic clamp (EHC) was performed in 18 pts (age: 60±11, ejection fraction 42±10) before coronary angioplasty (PTCA).Repeat resting echocardiography was performed 4 months after PTCA. DE viability in dysfunctional (D) segments (S) was defined as improvement in regional WMS by ≥1 grade during DE. S were defined as PET viability, if the mean metabolic rate of glucose (MRG, μmol/min/g) was ≥0.25. Out of 114 D-S, 70 (60%) were PET-viable and 54 (46%) DE-viable (concordance of 77%). A total of 53 D-S were revascularised. After PTCA 25 (47%) S improved, of which, 24 (96%) were PET viable and 24 (96%) DE viable and 26 S did not improve of which 21 (81%) were PET non-viable and 13 (50%) were DE non-viable. PET and DE had similar sensitivity, 96% vs 96%, negative PV, 95% vs 93% and positive PV, 83% vs 65% (p=NS). However, specificity of PET was greater than DE, 81% vs 50% (p=0.02). In conclusion: In pts with moderate LV dysfunction both quantitative FDG PET during EHC and DE have high accuracy in identifying myocardial viability although the specificity of PET is greater than DE.