Association of coronary microvascular dysfunction and cardiac muscle injury in acute myocardial infarction: results of comparison of dynamic SPECT and cardiac MRI.

Aim      To study the interrelation of changes in coronary microcirculation by data of dynamic single photon emission computed tomography (SPECT) and myocardial injury by data of magnetic resonance imaging (MRI) in patients with acute myocardial infarction (AMI).Material and methods  The study included patients admitted to the emergency cardiology department with new-onset AMI. Contrast-enhanced cardiac MRI was performed for all patients on day 2-7 of admission. Dynamic SPECT of the myocardium with evaluation of semiquantitative and quantitative parameters of perfusion was performed on day 7-10.Results All patients were divided into two groups based on the type of MR contrast agent accumulation: 1) patients with the ischemic type of contrast enhancement (n=34; 62 %); 2) patients with the non-ischemic type of contrast enhancement (n=21; 38 %). According to data of myocardial perfusion scintigraphy (MPS), the group of ischemic MR pattern had larger perfusion defects at rest and during a stress test. Moreover, this group was characterized by lower global stress-induced blood flow and absolute and relative myocardial flow reserve (MFR). When the study group was divided into patients with transmural (n=32; 58 %) and non-transmural (n=23; 42 %) accumulation of the MR-contrast agent, lower values of global stress-induced blood flow and of absolute and relative MFR were observed in the group of transmural MR-enhancement pattern. A moderate inverse correlation was found between the stress-induced myocardial blood flow and the volume of myocardial edema (r= -0.47), infarct area (r= -0.48) and microvascular obstruction area (r= -0.38).Conclusion      The variables of dynamic SPECT characterizing microcirculatory disorders that are independent on or due to injuries of the epicardial coronary vasculature reflect the severity and depth of structural changes of the myocardium in AMI. In this process, quantitative variables of myocardial perfusion are interrelated with the myocardial injury more closely than semiquantitative MPS indexes. The findings of the present study can also contribute to the heterogenicity of a patient group with acute coronary syndrome and AMI. Further study is required for understanding the prognostic significance of dynamic SPECT parameters.

[State of the art mathematical methods of the coronary blood flow modelling: background and clinical value].

X-ray computed tomography coronary angiography (CTCA) is a current method for diagnosing ischemic heart disease. Although this method has a high specificity and a negative predictive value in diagnosing coronary obstructions, there are limitations in determining the hemodynamic significance of the stenosis. Extensive use of noninvasive methods for evaluation of coronary hemodynamics, specifically evaluation of the fractional flow reserve (FFR) is limited due to its high cost and risks of complications. Mathematical modeling of coronary circulation and its reserve based on CTCA data is an up-to-date method that has been experimentally confirmed and clinically validated. This method showed a high diagnostic efficacy in several large studies that used the invasive determination of FFR as a "gold standard". This review addresses the current state of studies on mathematical modeling for fractional coronary reserve in patients with ischemic heart disease, as well as the limitations and prospects of this method.

Cardiac 123I-mIBG scintigraphy for prediction of catheter ablation outcome in patients with atrial fibrillation.

BACKGROUND: Previous studies show inconsistent results on the role of innervation imaging (with 123I-mIBG) in predicting late atrial fibrillation (AF) recurrence after catheter ablation (CA). These studies included patients with paroxysmal AF and studied prognostic value of post-CA I-123-mIBG parameters. Current study investigated the ability of pre CA 123-I-mIBG imaging to predict late AF recurrence in patients with persistent AF. METHODS: 123I-mIBG cardiac imaging was performed before CA in 82 patients with persistent AF. Patient was followed for 12 months. RESULTS: Multivariable analysis demonstrated that late heart-to-mediastinum ratio (H/Mlate) and washout rate (WR) were independent predictors of AF recurrence. ROC-curve analysis data showed that H/Mlate <1.6 (sensitivity 73.53%, specificity 81.3%, AUC 0.792, P < .001) and WR > 25.11 (sensitivity 70.6%, specificity 70.8.3%, AUC 0.712, P < .001) indicate high probability of AF relapses during 12 months after CA. CONCLUSION: Pre-CA parameters of global cardiac sympathetic activity estimated by 123I-mIBG scintigraphy are associated with late AF relapses in persistent AF patients with normal LVEF and absence of significant CAD.

[123 I-MIBG scintigraphy in the assessment of heart failure prognosis and effectiveness of cardiac resynchronization therapy].

Cardiac resynchronization therapy (CRT) is one of the methods of treating patients with chronic heart failure, which can reduce the mortality rate of this group. Scintigraphic assessment of sympathetic myocardial innervation allows us to evaluate the heart failure prognosis and the effectiveness of interventional treatment. The method is based on use of the radiopharmaceutical 123 I-methiodiobenzylguanidine (123 I-MIBG), which is a structural analogue of norepinephrine and is able to selectively accumulate in the sympathetic nerve endings. This review includes a brief description of norepinephrine metabolism and pharmacokinetics of 123 I-MIBG in the sympathetic nerve ending, a brief description of the study methodology and the clinical significance of this method in patients with heart failure. Particular attention is paid to the possibilities of using this method in patients with severe chronic heart failure before and after CRT.

[Perfusion-Metabolic Myocardial Scintigraphy in Prognosis of Left Ventricular Remodeling After Complex Surgical Treatment of Ischemic Cardiomyopathy].

PURPOSE: To study capabilities of perfusion-metabolic myocardial scintigraphy for prediction of the left ventricular (LV) reverse remodeling after comprehensive surgical treatment of ischemic cardiomyopathy (ICMP). METHODS: The study included ICMP patients aged 56±7 years (n=32) who underwent surgical correction of LV dysfunction (myocardial revascularization, LV reconstruction, and mitral valve restoration). Inclusion criteria were significant coronary artery disease; myocardial infarction; New York Heart Association (NYHA) class III-IV heart failure; LV ejection fraction (EF) ≤45%; LV end-systolic index (ESI) >60 mL/m2; and LV akinesia or dyskinesia according to echocardiography. Before surgery all patients were subjected to scintigraphy with 99mTc-MIBI (to assess perfusion) and with 123I-BMIPP (to assess myocardial metabolism). Scintigraphy results were expressed as median and lower; upper quartile (Me [lQ; hQ]). The clinical status and ventricular volume indicators were evaluated before surgery, in the early post-operative period (up to 4 weeks), and in the late post-operative period (12 months). RESULTS: At 12 months after intervention patients were divided into two groups: group 1 comprised patients (n=18) with beneficial outcome of the operation that stopped LV remodeling (ESI decreased, remained unchanged, or increased by.

Method for Studying the Myocardial Blood Flow Reserve by Load Dynamic Single-Photon Emission Computed Tomography.

We developed a method for collection and processing of scintigraphic data to estimate myocardial reserve in a gamma-chamber with cadmium-zinc-telluride detectors. Dynamic single-photon emission computed tomography of the heart with (99m)Tc-Technetril was performed in 16 coronary heart disease patients at rest and during pharmacological load. During data processing, regions of interest from the cavity and the myocardium of the left ventricle were formed and activity-time curves were constructed. The index of myocardial blood fl ow reserve was calculated as the difference between two ratios of the mean gamma-count from the myocardial area to the area under the left ventricle cavity curve (peak) during load and at rest. The mean indices of myocardial reserve in healthy volunteers and patients with coronary artery atherosclerosis were 1.86 (1.59; 2.20) and 1.39 (1.12; 1.69), respectively. The development of the method for studying myocardial reserve by single-photon emission computed tomography is an urgent problem and requires further investigations.

[Dynamic single-photon emission computed tomography as a method of identification of multivessel coronary artery disease].

Objective: The aim of this study was to determine the informative value of dynamic tomoscintigraphy in detection of multivessel coronary artery disease (CAD). Material and Methods: Patients with multivessel CAD (n= 16) and healthy volunteers (n= 9) underwent dynamic cardiac single photon emission computed tomography with 99mТс-MIBI at rest and during pharmacological stress-test. Processing of acquired results involved the formation of regions of interest from the cavity and the myocardium of the left ventricle used to create activity-time curves. Coronary flow reserve index was defined as a quotient of two ratios of the mean counts from the myocardial region to the integral activity in the left ventricular cavity for the studies performed during pharmacological stress test and at rest. Results: The mean values of coronary flow reserve index were 1.86 (1.59; 2.2) in group of healthy volunteers and 1.39 (1.12; 1.69) in patients with multivessel CAD. When the value of this index was less than 1.77, the method allowed for detection of three-vessel CAD with the sensitivity and specificity rates of 81.8% and 66.7%, respectively. Conclusion: Performing the standard myocardial perfusion scintigraphy in combination with the method of coronary flow reserve index assessment allows for enhancement of the diagnostic value of scintigraphic approach in the evaluation of coronary circulation disturbances in multivessel CAD.