Endothelial dysfunction in systemic lupus erythematosus: evaluation with 13N-ammonia PET.

UNLABELLED: Systemic lupus erythematosus (SLE) affects multiple organs and systems, severely involving the cardiovascular system. The aim of this study was to evaluate the presence of endothelial dysfunction with (13)N-ammonia PET in asymptomatic SLE patients. METHODS: We enrolled 16 women with SLE and 16 healthy women. Myocardial blood flow (MBF) was quantified in a 64-slice PET/CT scanner at rest, during a cold pressor test (CPT), and during stress. Endothelium-dependent vasodilation index, %ΔMBF, and myocardial flow reserve (MFR) were calculated. RESULTS: There were 16 women in the SLE group (mean age ± SD, 31.4 ± 8.3 y) and 16 women in the healthy control group (31.5 ± 11.1 y). Mean endothelium-dependent vasodilatation index and %ΔMBF were significantly lower in SLE patients (1.18 ± 0.55 vs. 1.63 ± 0.65, P = 0.04, and 18 ± 55 vs. 63 ± 65, P = 0.04, respectively). MFR was also lower in the SLE group (2.41 ± 0.59 vs. 2.73 ± 0.77, P = 0.20). CONCLUSION: SLE patients who are free of active disease present abnormal coronary flow and endothelial dysfunction. It is necessary to develop and intensify treatment strategies directed to CAD in SLE patients.

Effect of ezetimibe-simvastatine over endothelial dysfunction in dyslipidemic patients: assessment by 13N-ammonia positron emission tomography.

BACKGROUND: Dyslipidemias constitute an independent risk factor for the development of atherogenesis and they also predispose to the development of endothelial dysfunction (ED). Using PET with (13)N-ammonia, it is possible to quantify myocardial blood flow (MBF) in mL/min/g and to quantitatively evaluate ED. With the use of lipid lowering therapy it is possible to reduce ED and increase the MBF and the endothelial-dependent vasodilation index (ENDEVI). In this study, we aimed to evaluate with (13)N-ammonia PET the benefic effects of the combined treatment ezetimibe/simvastatine on the endothelial function of dyslipidemic patients after 8 weeks of treatment. MATERIAL AND METHODS: Fourteen consecutive patients with dyslipidemia diagnosis and 17 healthy volunteers were studied with a three phase [rest, Cold Pressor Test (CPT), and adenosine-induced hyperemia] (13)N-ammonia PET for MBF quantification assessment. A second PET study was performed in the dyslipidemic group after 8 weeks of treatment with ezetimibe/simvastatine (10/40 mg). Myocardial flow reserve (MFR), ENDEVI, and %ΔMBF were calculated. RESULTS: Total cholesterol, LDL cholesterol, HDL cholesterol, and triglycerides concentrations were markedly altered in the dyslipidemic group and after 8 weeks of treatment these values improved. Dyslipidemic patients showed endothelial dysfunction when compared with the control group, (MFR 2.79 ± 0.94 vs 3.15 ± 0.48, P < 0.05 ; ENDEVI 1.28 ± 0.25 vs 1.53 ± 0.24, P < 0.05; and %ΔMBF 29.08 ± 24.62 vs 53 ± 24.60%, P < 0.05, respectively). After 8 weeks of treatment, we found a significant increase in all the endothelial function markers (MFR: 3.14 ± 0.86, P < 0.05, ENDEVI 1.65 ± 0.23, P < 0.05; %ΔMBF: 65.21 ± 23.43, P < 0.05). CONCLUSIONS: Dyslipidemic patients show endothelial dysfunction measured with (13)N-ammonia PET. Treatment with ezetimibe/simvastatine was effective improving the lipid profile as well as the endothelial function of these patients. PET may be a useful tool to monitor vascular reactivity and regression/progression of coronary atherosclerosis after pharmacologic interventions.

Functional impact of coronary stenosis observed on coronary computed tomography angiography: Comparison with ¹³N-ammonia PET.

BACKGROUND AND AIMS: We undertook this study to evaluate the functional impact of coronary abnormalities in patients with suspected coronary artery disease (CAD) by means of integrated positron emission tomography (PET) and coronary computed tomography angiography (CCTA) scan obtained on a hybrid state-of-the-art PET/CT scanner. METHODS: We studied 29 consecutive, patients with a clinically suspected intermediate risk for CAD, using a hybrid PET/CT 64 slice scanner. During a single scanning session, CCTA was performed for coronary anatomy evaluation, and a rest/adenosine stress (13)N-ammonia PET was performed for myocardial perfusion assessment in 3D mode with CT attenuation correction. RESULTS: Twenty four (82.7%) patients had atherosclerosis detected by CCTA; 15 patients had significant (≥50%) coronary stenoses and all 15 patients showed ischemia by PET; moreover, 10/15 patients had a Summed Stress Score >12.20/24 and 83.3% patients with atherosclerosis detected by CCTA showed ischemia by PET. Two of five patients with normal coronary arteries showed ischemia by PET. CCTA agreement in positive identification of PET ischemia was 91% and agreement in ruling out ischemia was 43%; PET agreement in detecting CCTA atherosclerosis was 83%, and agreement in ruling it out was 60%. CONCLUSIONS: We found a strong relation between significant coronary stenosis identified by CCTA and ischemia by PET. However, in cases with low-grade stenosis, PET scan can assess the functional significance of atherosclerotic abnormalities.

Endothelial dysfunction in recently diagnosed type 2 diabetic patients evaluated by PET.

PURPOSE: To demonstrate the presence of endothelial dysfunction (ED) in asymptomatic patients with type 2 diabetes mellitus (DM) by using (13)N-ammonia-positron emission tomography (PET). PET can identify ED by quantifying myocardial blood flow (MBF) during rest, cold pressor test (CPT), and pharmacologic stress. The endothelial-dependent vasodilation index (EDVI), myocardial flow reserve (MFR), and the percentage of the change between rest and CPT (%DeltaMBF) are markers of endothelial function. PROCEDURES: Thirty-nine subjects were studied (19 women and 20 men); 22 recently diagnosed type 2 diabetic patients and 17 healthy controls (HC). A three-phase (13)N-ammonia-PET was performed. RESULTS: Mean EDVI was 1.208 +/- 0.34 vs. 1.55 +/- 0.37 (diabetic vs. HC group, respectively) (p = 0.002), MFR was 2.803 +/- 1.39 vs. 3.27 +/- 0.72 (p = NS), and the %DeltaMBF was 20 +/- 34% vs. 55 +/- 37% (p = 0.002). Rest MBF and CPT MBF were normalized to the rate pressure product (RPP). EDVI' and %DeltaMBF' were calculated using the corrected values for the RPP. Mean EDVI' was (0.864 +/- 0.250 vs. 1.110 +/- 0.238, p = 0.004) and mean %DeltaMBF' was (-8.2 +/- 14.7% vs. 4.5 +/- 12.1%, p = 0.005). CONCLUSIONS: Asymptomatic, recently diagnosed type 2 diabetes patients present ED that can be quantified by (13)N-ammonia-PET.