Ischemic patterns assessed by positron emission tomography predict adverse outcome in patients with idiopathic dilated cardiomyopathy

Although patients with idiopathic dilated cardiomyopathy (DCM) have no coronary artery disease, regional impairment of myocardial perfusion combined with preserved metabolism has been found using positron emission tomography (PET). Our aim was to assess the prognostic relevance of PET-mismatch between stress myocardial perfusion and glucose uptake on clinical outcome in DCM. In 24 patients with DCM who underwent both myocardial perfusion and metabolism PET scanning, "mismatch" was assessed and the association with clinical outcome (hospitalization, mortality, and heart transplantation) was investigated. Mismatch was found in 16 patients (66.7%). Univariate analysis showed that the presence of mismatch was associated with adverse outcome (P = 0.03). After adjustment for sex and age, the association remained significant with an adjusted relative risk of 10.4 (95% CI 1.1-103; P = 0.04) for death, heart transplant, or hospitalization. Univariate analysis also showed that a higher extent of mismatch was significantly associated with adverse outcome (P = 0.02). After adjusting for sex and age, the association remained significant with an adjusted relative risk of 6.5 [95% CI 1.2-36; P = 0.03] for death, heart transplantation, or hospitalization. PET stress perfusion-metabolism mismatch, indicative for ischemia, is frequently found in DCM patients and related to a poorer outcome

Abnormalities in myocardial contractility, metabolism and perfusion reserve in non-stenotic coronary segments in heart failure patients

Objective: Myocardial blood flow (MBF) reserve is impaired in congestive heart failure (CHF), while fluorine-18-deoxyglucose ((18)FDG) uptake is relatively preserved. To determine whether this mismatch could be interpreted as ischemia, we performed dobutamine stress echocardiography (DSE). Methods: 12 males with coronary artery disease (CAD) and CHF were compared with 12 controls with similar CAD but normal left ventricular (LV) function. MBF in non-infarct-related artery areas was assessed using [N-13]ammonia positron emission tomography (PET), at rest and after dipyridamole infusion and (18)FDG uptake was determined. DSE was performed with doses up to 40 mug/kg per min. Results: In areas with non-stenotic arteries MBF reserve was more impaired in CHF patients (1.6+/-1-0.6 vs. 2.2+/-0.5; CHF versus normal LV, respectively,

Effect of left ventricular function on diagnostic accuracy of FDG SPECT

Objectives: Fluorine-18 fluorodeoxyglucose (FDG) SPECT has emerged as an alternative to dedicated PET imaging. However, it remains uncertain whether FDG SPECT is an as accurate for viability assessment as FDG PET in patients with severely reduced left ventricular function. The aim of the study was to assess the diagnostic accuracy of FDG SPECT in a head-to-head comparison with FDG PET, and divide the patients according to the severity of left ventricular dysfunction. Methods: A total of 47 patients, with a history of myocardial infarction underwent FDG/perfusion (Tc-99m-sestamibi or Tl-201) SPECT as well as FDG/N-13-ammonia PET. The patients were divided into 2 subgroups based on the left ventricular ejection fraction (LVEF) (35% cutoff). The left ventricular myocardium was divided into 13 segments, and each segment was classified as viable or scar using a semi-quantitative scoring system based on defect severity and the presence or absence of perfusion-FDG mismatch. Results: Of the 47 patients studied, 23 had LVEF = 35% (high LVEF group; mean 47 +/- 6%). In the low LVEF group, 213 segments (71%) were dysfunctional, as compared to 102 (33%) in the high LVEF group. The agreement for detection of viability between PET and SPECT in the low LVEF group was 82% (kappa 0.63), which was not different from the agreement in the high LVEF group (85%, kappa 0.66, p = 0.42 versus low LVEF group). Conclusions: The results indicate that FDG SPECT can be used for tissue viability assessment regardless of the severity of left ventricular dysfunction