Olivier De Winter

Relationship between QRS duration, left ventricular volumes and prevalence of nonviability in patients with coronary artery disease and severe left ventricular dysfunction.

Patients with coronary artery disease (CAD), a QRS duration ≥120 ms and left ventricular ejection fraction (LVEF) ≤30% are potential candidates for cardiac resynchronization therapy (CRT). Our aim was to investigate the relationship between QRS duration, left ventricular volumes and prevalence of nonviable tissue in this patient population.

VE/Vco2 slope and oxygen uptake efficiency slope in patients with coronary artery disease and intermediate peakVo2

Background Peak exercise oxygen uptake (peakVo2) is a widely used prognosticator. Novel spirometric parameters, less affected by submaximal performance, such as the rate of increase of minute ventilation per unit decrease of carbon dioxide production (VE/Vco2 slope) and the oxygen uptake efficiency slope (OUES) have recently been introduced. Aim To evaluate the discriminative value of OUES, as compared to VE/Vco2 slope in patients with coronary artery disease (CAD) and intermediate peakVo2 values. Methods and results Bicycle spiroergometry was applied in 214 patients with CAD (age 67 ± 8 years, 85% men). OUES was strongly related to peakVo2 (r = 0.79). New York Heart Association (NYHA) class, 6-min walking distance, N-terminal probrain natriuretic peptide (NT-proBNP), inflammatory markers, left ventricular (LV) volumes and ejection fraction were evaluated. NT-proBNP levels predicted independently VE/Vco2-slope and OUES. Patients with intermediate peakVo2 (12–18 ml/kg per min) and increased VE/Vco2-slope (≥ 35) had higher NYHA class, lower walking distance, higher NT-proBNP levels and higher LV volumes as compared to patients with a similar peakVo2 but lower VE/Vco2-slope. Similar findings were found for patients with intermediate peakVo2 and high OUES/kg (median value > 15.3). Conclusion In CAD patients, OUES was strongly correlated with peakVo2. Both VE/Vco2 slope and OUES were independently associated with NT-proBNP levels. Both VE/Vco2 slope and OUES/kg were able to identify a subgroup of patients with an intermediate peakVo2 that was characterized by advanced remodelling and a higher degree of neurohumoral activation.

Clinical relevance of left ventricular volume assessment by gated myocardial SPET in patients with coronary artery disease.

Abstract Coronary artery disease (CAD) is the leading cause of mortality in the Western world. Multiple parameters have been investigated to predict prognosis in CAD patients. The prognostic value of the left ventricular ejection fraction (LVEF) in patients with CAD is well established. More recently, left ventricular (LV) volumes have also shown prognostic value. Due to the favourable imaging characteristics of technetium-99m (high count density), the development of 99mTc-labelled myocardial perfusion tracers has made it possible to perform an electrocardiogram-gated acquisition during routine myocardial perfusion imaging. This enables assessment of LVEF and LV volumes during myocardial perfusion scintigraphy. This review considers the possible prognostic abilities of LV volume assessment by gated cardiac SPET.

Tumour angiogenesis pathways: related clinical issues and implications for nuclear medicine imaging

Abstract. Tumour angiogenesis is essential for growth, invasion and metastasis. Retrospective studies suggest that it is an independent prognostic factor that merits prospective validation. Furthermore, as tumour blood vessels show many differences from normal vessels and are not genetically unstable, they form a key area for therapy development. However, as anti-angiogenic therapy is primarily cytostatic and not cytotoxic, novel tailor-made specific end-points for treatment monitoring are required. In this regard, suitable molecular parameters for imaging tumour angiogenesis by means of nuclear medicine are being explored. Here we review current knowledge on the multiple pathways controlling tumour angiogenesis and try to assess which are the most clinically relevant for nuclear medicine imaging. Parameters that may influence the imaging potential of radiopharmaceuticals for angiogenesis imaging such as molecular weight and structure, their targeted location within the tumour and their usefulness in terms of specificity and constancy of the targeted molecular pathway are discussed.

Agreement between four available algorithms to evaluate global systolic left and right ventricular function from tomographic radionuclide ventriculography and comparison with planar imaging.

Background and aimLeft and right ventricular ejection fractions (LVEF and RVEF) and end-diastolic and end-systolic volumes (LVEDV, RVEDV, LVESV and RVESV) can be calculated from tomographic radionuclide ventriculography (TRV). The aim of this study was to validate and compare these parameters obtained using four different TRV software programs (QBS, QUBE, 4D-MSPECT and BP-SPECT). MethodsLVEF obtained from planar radionuclide ventriculography (PRV) was compared with LVEF obtained from TRV using the four different software programs in 166 patients. Furthermore, ventricular volumes obtained using TRV (QBS, QUBE and 4D-MSPECT) were compared with those obtained using BP-SPECT, the latter being the only method with the validation of ventricular volumes in the literature. ResultsThe correlation of LVEF between PRV and TRV was good for all methods: 0.81 for QBS, 0.79 for QUBE, 0.71 for 4D-MSPECT and 0.79 for BP-SPECT. The mean differences±standard deviation (SD) were 3.16±9.88, 10.72±10.92, 3.43±11.79 and 2.91±10.39, respectively. The correlation of RVEF between BP-SPECT and QUBE and QBS was poor: 0.33 and 0.38, respectively. LV volumes calculated using QBS, QUBE and 4D-MSPECT correlated well with those obtained using BP-SPECT (0.98, 0.90 and 0.98, respectively), with mean differences±SD of 7.31±42.94, −22.09±36.07 and −40.55±39.36, respectively. RV volumes showed poorer correlation between QBS and BP-SPECT and between QUBE and BP-SPECT (0.82 and 0.57, respectively). ConclusionLVEF calculated using TRV correlates well with that calculated using PRV, but is not interchangeable with the value obtained using PRV. Volume calculations (for left and right ventricle) and RVEF require further validation before they can be used in clinical practice.

Comparison of the prognostic value of dipyridamole and dobutamine myocardial perfusion scintigraphy in hemodialysis patients

Screening for coronary artery disease (CAD) in hemodialysis patients is hampered by contraindications and/or limitations of the available techniques in this population. Myocardial perfusion scintigraphy (MPS) using dipyridamole has been considered inaccurate due to abnormally high basal levels of adenosine in uremia that could blunt the vasodilatory response. Since dobutamine may be more reliable, we directly compared the two in patients on hemodialysis. We performed MPS at rest and after separate dipyridamole or dobutamine stress in 121 chronic hemodialysis patients. More numerous, larger, and more intense reversible lesions were induced with dobutamine than with dipyridamole, mainly in the anteroseptal segments. Reversibility with dipyridamole but not dobutamine MPS was independently and strongly related with mortality associated with CAD and with fatal and non-fatal CAD. We hypothesize that the chronotropic action of dobutamine induced alterations of wall motion, leading to spurious perfusion defects, not unlike artifacts seen with left bundle branch block. Our study shows that even though dobutamine induced more pronounced myocardial ischemia than dipyridamole in chronic hemodialysis patients, dipyridamole MPS more accurately identifies patients at high risk for subsequent cardiac death or non-fatal CAD than dobutamine.

Accuracy of commercially available processing algorithms for planar radionuclide ventriculography using data for a dynamic left ventricular phantom

BackgroundAutomatic and semi-automatic algorithms to calculate ejection fraction (EF) from planar radionuclide ventriculography (PRV) have been used for many years in nuclear medicine. Validation of these algorithms is scarce and often performed on outdated versions of the software. Nevertheless, clinical trials where PRV is being used as the ‘gold standard’ for EF are numerous. Because of the importance attributed to the EF calculated by these programs, the accuracy of the resulting EF was assessed with a dynamic left ventricular physical phantom. MethodsA dynamic left ventricular phantom was used to simulate 21 combinations of various ejection fractions (7–66%) and end diastolic volumes (27–290 ml). For each combination, a planar radionuclide ventriculograph was acquired, converted to an interfile format and transferred into processing stations with 10 different contemporaneously available commercial algorithms. The gold standard was the ‘real’ EF of the phantom, derived from the exact volume of the ventricle in end diastolic and end systolic position. Correlation and Bland–Altman analysis was performed between the real EF and the calculated EF. ResultsThe correlation for all data was excellent (r=0.98), the mean difference was very acceptable (0.98%). Nevertheless, Bland–Altman analysis showed a significant trend in the difference between real and calculated EF, with a growing underestimation for higher ranges of EF, due to an overestimation of background in larger volumes compared to smaller ones. ConclusionThe determination of EF from PRV, calculated with commercially available algorithms, correlates closely to the real EF of a dynamic left ventricular phantom. This phantom can be used in the development and validation of algorithms for PRV studies, in software audits and in quality assurance procedures.

Myocardial perfusion imaging in the elderly: a review.

Coronary artery disease is a major cause of morbidity and mortality in the elderly population. As a result of ageing of the population and better medical, interventional and surgical treatment of patients with coronary artery disease, more and more elderly patients are referred to the cardiology department for diagnostic work-up. Stress testing, in combination with myocardial perfusion imaging, is routinely used in elderly patients, a population in which the diagnosis of significant coronary artery disease is often challenging because of atypical symptomatology. Since the introduction of technetium-99m ligands for myocardial perfusion imaging, it is possible to perform electrocardiogram-gated perfusion imaging. This not only improves the specificity of the test for coronary artery disease detection, but also enables the simultaneous assessment of left ventricular functional parameters. This article briefly overviews the possible stress modalities, diagnostic accuracy and prognostic value of myocardial perfusion imaging in elderly patients.

Diabetes and impaired fasting glucose as predictors of morbidity and mortality in male coronary artery disease patients with reduced left ventricular function

Objectives — To evaluate the prognostic value of impaired fasting glucose and diabetes mellitus in male patients with coronary artery disease and poor left ventricular function. Methods and results — From a prospective database on patients referred for gated myocardial perfusion imaging between 1998 and 2002 all male patients with a history of coronary artery disease and poor left ventricular function were selected. Poor function was defined as left ventricular ejection fraction ≤ 40%. Subjects were classified as non-diabetics with fasting blood glucose levels < 110 mg/dL, non-diabetics with impaired fasting glucose (fasting blood glucose between 110 and 125 mg/dL) and diabetics. Median follow-up was 2.7 years. End points were all-cause mortality, cardiac death and hospitalization for heart failure. One hundred and sixty patients were selected (age 65 ± 9 years and left ventricular ejection fraction 29 ± 8%). In univariate analysis atrial fibrillation, NYHA class, glycaemia and diabetes mellitus discriminated between survivors and non-survivors. In Cox multivariate regression analysis for all-cause mortality only NYHA class and diabetes mellitus remained significant. Kaplan Meier analysis showed that diabetics had the worst survival and non-diabetics with glucose < 110 mg/dL had the best survival. Non-diabetics with impaired fasting glucose had intermediate survival. Analysis for cardiac death/hospitalization for heart failure showed similar results. Conclusion — In male patients with coronary artery disease and impaired left ventricular function diabetes mellitus and fasting glucose are strongly predictive of poor outcome. Diabetics have the worst prognosis but non-diabetics with impaired fasting glucose also are at higher risk compared to nondiabetics with low fasting blood glucose.

False-negative Tc-99m MIBI scintigraphy in histopathologically proved recurrent high-grade oligodendroglioma.

Tc-99m MIBI is a small lipophilic radioligand that enters cells by diffusion and is preferentially trapped in mitochondria. As a result of the high mitochondrial activity in tumors, Tc-99m MIBI accumulates significantly more in tumor tissue compared with normal tissues. Accordingly, Tc-99m MIBI has been used successfully to visualize primary, metastatic, and recurrent tumor. In brain tumors, Tc-99m MIBI SPECT has been shown to identify tumor recurrence after treatment in high-grade gliomas. In this report, early (30 minutes after injection) and delayed (4 hours after injection) Tc-99m MIBI SPECT did not visualize a histopathologically proved recurrent high-grade oligodendroglioma. Increased vascular supply, disruption of the blood-brain barrier, high-grade cancer, and viability of tumor cells are decisive factors related to increased Tc-99m MIBI uptake in brain tumors. However, the authors’ results suggest that still other mechanisms may be involved in Tc-99m MIBI accumulation, which may account for false-negative imaging in brain tumors.