Combined myocardial perfusion scintigraphy and computed tomography: diagnostic and prognostic value in coronary artery disease

Modern imaging techniques occupy an important place in the diagnosis, selection of treatment and prognosis of patients with coronary artery disease. Hybrid imaging is a combination of two sets of diagnostic data that complement and enhance each other by comparing anatomical and functional characteristics. As a rule, hybrid imaging is synergistic, that is, more powerful, since the addition of new information leads to an increase in the sensitivity and specificity of each of the modalities separately.The review provides brief information on the diagnostic efficacy of myocardial perfusion scintigraphy (MPS), computerized tomography (CT) coronary angiography in comparison with invasive coronary angiography with fractional flow reserve. The diagnostic and prognostic significance of assessing calcium index with MPS, as well as CT coronary angiography combined with MPS in the diagnosis, risk stratification and prognosis of patients with coronary artery disease, is characterized in detail. A separate section is devoted to the importance of hybrid imaging in making decisions about myocardial revascularization

Coronary flow reserve in patients with heart failure with preserved ejection fraction

Aim. To study the parameters of myocardial blood flow (MBF) and coronary flow reserve (CFR) in patients with heart failure (HF) with preserved ejection fraction and evaluate their relationship with the severity of HF.Material and methods. The study included 47 patients (men, 68,7%) aged 65,0 (58,0; 72,0) years with left ventricular ejection fraction of 62 (56; 67)% and coronary artery stenosis <50%. Serum levels of N-terminal pro-brain natriuretic peptide (NT-proBNP) were assessed by enzyme immunoassay. MBF and CFR values were assessed using cardiac single photon emission computed tomography.Results. Depending on NT-proBNP levels, the patients were divided into 2 groups (p<0,001): the 1st group included (n=15) patients with NT-proBNP <125 pg/ml (58,2 [41,6; 70,7] pg/ml), while in the 2nd group (n=32) — with NT-proBNP ≥125 pg/ml (511,4 [249,8; 1578,1] pg/ml). The group of patients with high NTproBNP levels was characterized by higher values (by 33,8%, p=0,0001) of resting MBF and reduced CFR (by 14,7%, p=0,001) compared with patients with normal NT-proBNP level: resting MBF — 0,65 (0,44; 0,79) vs 0,43 (0,30; 0,58) ml/min/g; CFR — 2,21 (1,52; 2,83) vs 2,59 (2,47; 3,05), respectively. At the same time, MBF at stress did not differ between the groups. The relationship of NTproBNP levels with global CFR (p=0,012; r=-0,339) and MBF at rest (p=0,012; r=0,322) was established. A stepwise decrease in global CFR was revealed depending on the NYHA class as follows (p<0,001): 2,79 (2,52; 2,93); 1,8 (1,55; 2,08); 1,31 (1,23; 1,49) — for class I, II, and III, respectively.Conclusion. A decrease in CFR in patients with HF with preserved ejection fraction indicates impaired myocardial blood supply, which, in this group of patients, is associated with microcirculatory changes. At the same time, the severity of MBF alterations is closely related to HF severity

Association of impaired myocardial flow reserve with risk factors for cardiovascular diseases in patients with nonobstructive coronary artery disease

Aim. To reveal the association between disorders of myocardial blood flow and reserve, according to dynamic single photon emission computed tomography (SPECT), with risk factors for cardiovascular diseases (CVD) in patients with nonobstructive coronary artery disease (CAD).Material and methods. The study included patients with suspected stable nonobstructive (<50%) CAD. Based on the survey data, anamnesis, out- and in-patient medical records, we analyzed main CVD risk factors. All patients underwent dynamic myocardial SPECT and analysis of blood lipid profile in vitro. Depending on myocardial flow reserve (MFR), two groups were formed: 1. With reduced MFR <2,0 (rMFR); 2. With normal MFR ≥2,0 (nMFR).Results. The study included 47 patients divided into 2 following groups: the rMFR group consisted of 24 patients (15 men, age 56,3±9,1 years), the nMFR group — 23 patients (13 men, age 58,4±10,7 years). There was no significant difference in prevalence of CVD risk factors in groups. However, dyslipidemia was detected more often in rMFR patients (p=0,053): 58% vs 30%, respectively. In patients with rMFR, there were significantly higher levels of total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C). Correlation analysis revealed significant negative inverse relationships between MFR values with TC (ρ=-0,36, p=0,01) and LDL-C (ρ=-0,38, p=0,009). According to univariate logistic regression, significant predictors of reduced MFR were TC (odds ratio (OR), 2,32; 95% confidence interval (CI), 1,17-4,59; p=0,01) and LDL-C (OR, 2,16; 95% CI, 1,04-4,51; p=0,04). According to a stepwise multivariate logistic regression analysis, only TC was an independent predictor of a decrease in MFR (OR, 2,32; 95% CI, 1,17-4,59; p=0,02).Conclusion. MFR, determined by dynamic SPECT, is associated with TC and LDL-C levels. TC level is an independent predictor of a decrease in MFR

METABOLISM OF FATTY ACIDS IN LEFT VENTRICLE MYOCARDIUM AND THE EFFICACY PROGNOSIS OF CARDIO-RESYNCHRONIZING THERAPY IN DILATED CARDIOMYOPATHY PATIENTS

Aim. To study perfusion and metabolism of LV myocardium in patients with dilated cardiomyopathy (DCMP) and to invent on this basement a gamma-specific predictors for cardio-resynchronizing therapy (RT) efficacy. Material and methods. Totally 63 patients with DCMP included (41 male, 22 female) with mean age 55,4±8,3 y.o., having congestive heart failure (CHF) of III-IV NYHA. Before RT all patients underwent scintigraphy of myocardium with "Т (for perfusion assessment) and 123I (for fatty acids metabolism). Before and in 6 months after RT all patients underwent echocardiography to assess intracardiac hemodynamics.Results. In 6 months after RT all patients were divided into two groups: 1) EDV LV decreased by >15% (n= 39) — "responders", and 2) ESV LV decreased <15% (n=24) — "non-responders". Before RT groups did not significantly differ by pumping function of the ventricle. Significant difference was found by following pre-operational scintigraphic parameters: perfusion defect (PD) (9,22±5,06% and 12,5±4,22%, p<0,01), metabolism defect on earlier pictures (MD) (9,21±5,42% and 11,27±5,39%, p<0,01). The equation of multiple regression was invented, which may prognose the dynamics of end-systolic volume after RT.By the ROC analysis data the main prognostic significance for RT has the size of metabolism defect area and calculated value of end-systolic volume dynamics. The best threshold MD=7,35% and it confirms the efficacy of RT with 77,8% sensitivity and 66,7% specificity. The best threshold value of calculated end- systolic volume dynamics — 34,02 confirms the 87,5% sensitivity and 100% specificity of RT.Conclusion. The data collected during metabolic myocardial gamma-scintigraphy may be used in the complex of methods that allow to predict the efficacy of cardio- resynchronizing therapy

Superimposed single-photon emission computed tomography and X-ray computed tomography of the heart: Methodical aspects

Global radiology and nuclear medicine have recently shown a clear trend towards hybrid (combined, superimposed) studies. Unfortunately, the Russian literature virtually lacks both methodological and research works on this topic. The basis for this paper was the guidelines of the North American Society of Nuclear Medicine and Molecular Imaging, the North American Society of Nuclear Cardiology, and the Society of Cardiovascular Computed Tomography and the principles as jointly set out by the European Society of Nuclear Medicine, the European Society of Radiology, and the European Association of Nuclear Medicine.The purpose of the paper is to familiarize readers with some methodical aspects of performing superimposed single-photon emission computed tomography (SPECT) and X-ray computed tomography (CT) of the heart. This publication discusses the main indications for and contraindications to hybrid cardiological studies and gives other data that are useful to select patients for examination. A patient's preparation and prevention measures are described. There is information on major radiotracers and equipment for superimposed studies. There are imaging parameters and information on the correction of gamma-ray quantum absorption according to CT data. The paper concerns the interpretation of the results of identifying coronary artery calcification and those of CT coronarography and myocardial perfusion scintigraphy. It presents the methodical aspects of superimposition of radionuclide and CT images, the possible sources of errors during superimposed SPECT/CT, and recommendations for making a diagnostic conclusion. The issues of radiation load and radiation safety are discussed

NOVEL METHODS OF PATIENTS SELECTION FOR THE CARDIAC RESYNCHRONIZING THERAPY IN NON-ISCHEMIC CARDIOMYOPATHY

Aim. To study a range of selection methods for cardiac resynchroizing therapy (CRT) and to evaluate the possibility of their application in clinical practice for treatment improvement.Material and methods. Totally 88 patients studied with the diagnosis dilation cardiomyopathy (DCMP) at the age 32-75 y. o. (55±12), HF III NYHA, ejection fraction (EF) of the LV (LV) was 30,1±3,8%, distance in 6-minute walking test — 290,5±64,3 m, end-diastolic volume (EDV) — 220,7±50,9 ml, intra- and interventricular dyssynchrony was more than 120 ms. At the stage of selection the patients were separated to 3 groups: first — 28 patients — the defect of myocardium metabolism (DMM) was assessed using radionuclide methods; second — 24 patients — systolic velocity assessed of fibrous annulus of tricuspid valve of the right ventricle (Srv); third — 36 patients — controls.Results. Control assessments were done in 1 year. Clinical responders for CRT were 69 patients (78,5%), not responded to CRT — 19 patients (21,5%). In assessment by the each method of selection it was revealed that in the 1st group there were 3 (10,7%) nonresponders, 6 (25%) in 2nd group, 10 (27,7%) in the 3rd. In the 1st group the responders were 25 (89,3%) of patients, whose LV DMM before CRT was 15%. If it was more than 15%, patients were nonresponders. In the second group the responders were 18 (75%) of patients, whose Srv before CRT was more than 10 m/s, in average — 12,5±2,1, (р=0,0001).Conclusion. 1. Maintaining of myocardium metabolism (DMM LV less than 15%) is a predictor of CRT efficacy in DCMP patients. 2. Srv is an independent predictor of the CRT response and makes it with the sensitivity 85% and specificity 83% to reveal the responders to CRT at the stage of selection. 3. While selecting patients to CRT it is aimful to use all described methods together to improve quality of treatment

SEARCH FOR EFFECTIVENESS PREDICTORS OF BIVENTRICULAR STIMULATION IN PATIENTS WITH DRUG-REFRACTORY SEVERE CHRONIC HEART FAILURE

Aim. To reveal factors influencing the results of cardiac resynchronizing therapy (CRT) and to analyze the possibility of radionuclide investigation methods usage for evaluation of indications for this method.Material and methods. Totally 64 patients included with dilated cardiomyopathy (DCMP) at the age of 32 to 75 y. o., with chronic heart failure (CHF) III NYHA, with left ventricle ejection fraction (EF LV) 30,1±3,8%, 6-minute walking test at 290,5±64,3 m, end-diastolic volume (EDV) — 220,7±50,9 ml. All patients before CRT and after 1 year underwent Holter ECG monitoring. Patients were divided into 2 groups by the type of AF registration. Into the 1st group 40 patients included (62,5%) patients, who had permanent AF with 1-3 years anamnesis, mean 2±1,2 years. Second group consisted of 24 (37,5%) patients with sinus rhythm (SR). Before CRT 28 patients underwent balanced radionuclide ventriculography (BRVG) with EF LV increase estimation. To all the CRT devices were implanted with defibrillation function, and for patients with AF complete AV-block created.Results. After 1 year all patients had positive clinical dynamics: LV EF increased to 42,8±4,8% (p≤0,001), HF class decreased from III to II, 6-minute distance increased to 377,2±45,3 m (p≤0,001). EDV LV decreased to 197,9±47,8 ml (p≤0,005). In 24 (37,5%) patients during a year sinus rhythm spontaneously returned. It was found that in patients with SR before the beginning of the study increase of EF during 1 year of CRT was 14%, and EDV decreased by 32 ml. In patients with permanent AF after 1 year CRT EF increased by 9%, and EDV decreased only by 13 ml. In patients with baseline AF and spontaneous SR EF increased by 13% and EDV decreased by 18 ml. Second stage of the study was the division of patients into two groups of responders and nonresponders by the level of EF increase after 12 months CRT and retrospective evaluation of metabolism defect of myocardium (MDM), measured by BRVG. Responders were the patients who, before CRT had MDM less than 15%, but if in increased 15%, patients were non-responders.Conclusion. Hence the increase and maintenance of SR at the background of CRT in DCMP and AF helps to improve the parameters and clinical picture of CHF. Maintenance of fatty acid metabolism (MDM LV less than 15%) is a predictor of CRT effectiveness in DCMP

The current status of CZT SPECT myocardial blood flow and reserve assessment: Tips and tricks

Cardiac PET-derived measurements of myocardial blood flow (MBF) and myocardial flow reserve (MFR) are proven robust indexes of the severity of coronary artery disease (CAD). They facilitate the diagnosis of diffuse epicardial and microvascular disease and are also of prognostic significance. However, low availability and high cost have limited their wide clinical implementation. Over the last 15 years, cadmium zinc telluride (CZT)-based detectors have been implemented into SPECT imaging devices. Myocardial perfusion scintigraphy can be performed faster and with less radiation exposure as compared with standard gamma cameras. Rapid dynamic SPECT studies with higher count rates can be performed. This technological breakthrough has renewed the interest in SPECT MBF assessment in patients with CAD. Currently, two cardiac-centered CZT gamma cameras are available commercially—Discovery NM530c and D-SPECT. They differ in parameters such as collimator design, number of detectors, sensitivity, spatial resolution and image reconstruction. A number of publications have focused on the feasibility of dynamic CZT SPECT and on the correlation with cardiac PET and invasive coronary angiography measurements of fractional flow reserve. Current study reviews the present status of MBF and MFR assessment with CZT SPECT. It also aims to provide an overview of specific issues related to acquisition, processing and interpretation of quantitative studies in patients with CAD