Inter- and Intraobserver Repeatability of Myocardial Flow Reserve Values Determined with SPECT Study Using a Discovery NM530c Camera and Corridor 4DM Software.

BACKGROUND: Myocardial blood flow (MBF) and flow reserve (MFR) examination, especially useful in the diagnosis of multivessel coronary artery disease (CAD), can be assessed with a cadmium-zinc-telluride (CZT) SPECT gamma camera, as an alternative to the expensive and less available PET. However, study processing is not free from subjective factors. Therefore, this paper aims to evaluate intra- and interobserver repeatability of MBF and MFR values obtained by the same operator and two independent operators. METHODS: This study included 57 adult patients. MBF and MFR were assessed using a Discovery NM530c camera in a two-day, rest/dipyridamople protocol, using 99mTc-MIBI. Data were processed using Corridor4DM software, twice by one operator and once by another operator. RESULTS: The repeatability of the assessed values was quite good in the whole myocardium, LAD and LCX vascular territories, but was poor in the RCA territory. CONCLUSIONS: The poor repeatability of MBF and MFR in RCA vascular territory can be explained by poor automatic orientation of the heart axis during post-processing and a so-called "cardiac creep" phenomenon. Better automatic heart orientation and introduction of automatic motion correction is likely to drastically improve this repeatability. In the present state of the software, PET is better for patients requiring assessment of MFR in the RCA territory.

N-Terminal Pro-Brain Natriuretic Peptide and Right Ventricular Diameter Are Related to Aspirin Resistance in Coronary Artery Disease Patients.

Background and Objectives: Resistance to ASA (ASAres) is a multifactorial phenomenon defined as insufficient reduction of platelet reactivity through incomplete inhibition of thromboxane A2 synthesis. The aim is to reassess the prevalence and predictors of ASAres in a contemporary cohort of coronary artery disease (CAD) patients (pts) on stable therapy with ASA, 75 mg o.d. Materials and Methods: We studied 205 patients with stable CAD treated with daily dose of 75 mg ASA for a minimum of one month. ASAres was defined as ARU (aspirin reaction units) ≥550 using the point-of-care VerifyNow Aspirin test. Results: ASAres was detected in 11.7% of patients. Modest but significant correlations were detected between ARU and concentration of N-terminal pro-brain natriuretic peptide (NT-proBNP) (r = 0.144; p = 0.04), body weight, body mass index, red blood cell distribution width, left ventricular mass, and septal end-systolic thickness, with trends for left ventricular mass index and prothrombin time. In multivariate regression analysis, log(NT-proBNP) was identified as the only independent predictor of ARU-partial r = 0.15, p = 0.03. Median concentrations of NT-proBNP were significantly higher in ASAres patients (median value 311.4 vs. 646.3 pg/mL; p = 0.046) and right ventricular diameter was larger, whereas mean corpuscular hemoglobin concentration was lower as compared to patients with adequate response to ASA. Conclusions: ASAres has significant prevalence in this contemporary CAD cohort and NT-proBNP has been identified as the independent correlate of on-treatment ARU, representing a predictor for ASAres, along with right ventricular enlargement and lower hemoglobin concentration in erythrocytes.

Circumferential strain of carotid arteries does not differ between patients with advanced coronary artery disease and group without coronary stenoses.

PURPOSE: Speckle tracking echocardiography is widely used for the analysis of myocardial function. Recently, circumferential strain (CS) of carotid arteries was postulated as novel indicator of vascular function. Our aim was to characterize and compare CS of carotid arteries in patients with advanced coronary artery disease and controls without significant coronary stenoses. PATIENTS/METHODS: We compared CS of both common carotid arteries (CCA) in the 25 patients with three-vessel coronary artery disease (3VD) (mean age 69±9 years, 9 male) and in 16 age-matched subjects without significant coronary lesions (C) (69±8 years, 7 male). Additionally in 11 patients we estimated pulse wave velocity (PWV) and assessed the correlation between PWV and CS. Short-axis images of arteries were acquired for strain analysis with linear probe of echocardiograph. The assessment of CS was performed off-line by two observers. RESULTS: The intraobserver variability for the CS (coefficient of variation) were 4.9 and 5.4% for left and right CCA and interobserver variability were 11.7% and 12.5%, respectively. The mean CS for left and right CCA did not differ between compared groups. We did not find correlation between CS strain and PWV. The only difference was related to the more prevalent plaque presence and thicker intima-media complex (IMT) in 3VD (p=0.0039 for IMT of left CCA and p=0.016 for IMT of right CCA). CONCLUSIONS: The global CS of CCA, contrary to IMT, did not allow for differentiation between 3VD and C subjects. Despite good feasibility and concordance of CS measurements its clinical significance remains to be established.