Myocardial Perfusion Imaging – ABC CARDIOL

IJCS

Editorial

Myocardial Perfusion Imaging: Always Evolving

Renata Christian Martins Felix

Myocardial perfusion assessed by nuclear medicine began to be used in clinical practice in the 1970s with the radiotracer 201-thallium chloride in two-dimensional images.

Advances in the development of equipment, from the possibility of three-dimensional images by single-photon emission computed tomography (SPECT), and new tracers, such as those linked to 99-technetium, have allowed the consolidation of nuclear cardiology as a non-invasive tool with high diagnostic accuracy in the context of coronary artery disease.

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ABCIC

Review Article

My Approach to Functional Analysis in Computed Tomography Angiography: Myocardial Perfusion and FFRct

Gustavo Corrêa de Almeida Teixeira et al. Bruno Vicente Gomes de Castro Douglas Carli Silva Tiago Magalhães

Abstract

Coronary computed tomography angiography (CCTA) is an effective noninvasive method for detecting atherosclerotic disease, especially in symptomatic patients with low-to-moderate disease probability. Despite good accuracy in detecting obstructions, its relationship with functional lesion severity is limited. For a more accurate assessment, anatomical evaluation can be associated with myocardial computed tomography perfusion and fractional flow reserve derived from CCTA (FFRct). Myocardial perfusion computed tomography identifies areas of ischemia. FFRct, which assesses the hemodynamic significance of stenoses, has shown high accuracy and can reduce the need for invasive catheterizations. The image acquisition and interpretation protocols are essential to ensure reliable results and appropriate management of patients with coronary artery disease.

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Editorial

Analysis of Myocardial Flow Reserve Using the CZT Camera. Additional Value to Perfusion and Functional Information in Identifying the Cause of Chest Discomfort

Paola Emanuela Poggio Smanio

Chest discomfort is one of the most common symptoms that often leads people to hospital emergency services. The importance of rapid differentiation between acute cardiac ischemic syndrome secondary to significant obstruction of the coronary arteries (obstructive CAD) and other conditions that also causes chest discomfort promptly is essential.

Many patients are discharged inadvertently and progress to acute events, on the other hand, others remain for several days occupying precious beds in hospital emergency rooms without the cause being cardiological.

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Editorial

Chronic Chagasic Cardiomyopathy: Influence of Physical Exercise

Gustavo Augusto Ferreira Mota et al. Mariana Gatto Vitor Loureiro da Silva Paula Felippe Martinez Marina Politi Okoshi

Chronic Chagas cardiomyopathy results from infection with Trypanosoma cruzi, transmitted by triatomine insects. The disease, endemic in Latin America, affects millions of individuals worldwide. In recent decades, the increase in migration has elevated the number of infected people in non-endemic regions from Europe and the United States. Chagas disease remains a neglected disease, characterized by difficulty in early diagnosis and poorly understood pathogenesis.

T. cruzi infects cardiomyocytes, immune cells, and fibroblasts, activating an inflammatory response that can reduce the parasite load and cause the death of infected cells. The parasite induces the production of chemokines and cytokines that increase the microbicidal capacity of macrophages and stimulate nitric oxide synthases and the production of reactive oxygen species. CD4 and CD8 T lymphocytes also participate in the inflammatory response with the production of IFN-γ and degranulation of cytotoxic T lymphocytes that lysis compromised cells.

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Original Article

Exercise Training Reduces Inflammation and Fibrosis and Preserves Myocardial Function and Perfusion in a Model of Chronic Chagas Cardiomyopathy

Thayrine R. Damasceno et al. Denise M. Tanaka Enrico F. Magnani Rafael D. B. Oliveira … Danielle A. G. Pereira Ildernandes Vieira-Alves Virginia S. Lemos Jorge M. Cabeza Camila G. Fabricio Alessandra A. Resende Dawit A. P. Gonçalves Gustavo de Oliveira Zanetti Eduardo E. Vieira de Carvalho Marcus V. Simões Luciano F. L. Oliveira

Abstract

Background:

Chronic Chagas cardiomyopathy (CCC) is caused by an inflammatory process induced by Trypanosoma cruzi, which leads to myocarditis with reactive and reparative fibrosis. CCC progresses with myocardial perfusion abnormalities and histopathological events that affect cardiorespiratory fitness (CRF).

Objectives:

We evaluated the effects of aerobic physical training (APT) on myocardial perfusion and on morphological and functional impairments related with inflammation and fibrosis in Syrian hamsters with CCC. As a secondary objective, we analyzed the cross-sectional areas of the skeletal muscle.

Methods:

Hamsters with CCC and their respective controls were divided into four groups: CCC sedentary, CCC-APT, sedentary control and APT control. Seven months after infection, the animals underwent echocardiography, myocardial perfusion scintigraphy and cardiopulmonary exercise testing. Moderate-intensity APT was performed for fifty minutes, five times a week, for eight weeks. Subsequently, the animals were reassessed. Histopathological analysis was conducted after the above-mentioned procedures. The level of significance was set at 5% in all analyses (p<0.05).

Results:

CCC sedentary animals presented worse myocardial perfusion defects (MPD) over time, reduced left ventricle ejection fraction (LVEF) and showed more inflammation and fibrosis when compared to other groups (mixed ANOVA analysis). Conversely, APT was able to mitigate the progression of MPD, ameliorate inflammation and fibrosis and improve CRF efficiency in CCC-APT animals.

Conclusions:

Our study demonstrated that APT ameliorated cardiac dysfunction, MPD, and reduced inflammation and fibrosis in CCC hamster models. Additionally, CCC-SED animals presented skeletal muscle atrophy while CCC-APT animals showed preserved skeletal muscle CSA. Understanding APT’s effects on CCC’s pathophysiological dimensions is crucial for future research and therapeutic interventions.

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Original Article

Association of Income Level and Ischemic Heart Disease: Potential Role of Walkability

Rodrigo Julio Cerci et al. Miguel Morita Fernandes-Silva João Vicente Vitola Juliano Julio Cerci … Carlos Cunha Pereira Neto Margaret Masukawa Ana Paula Weller Gracia Lara Luiza Silvello Pedro Prado Murilo Guedes Adriano Akira Ferreira Hino Cristina Pellegrino Baena

Abstract

Background

Socioeconomic status has been linked to ischemic heart disease (IHD). High-income neighborhoods may expose individuals to a walking-promoting built environment for daily activities (walkability). Data from the association between income and IHD is lacking in middle-income countries. It is also uncertain whether walkability mediates this association.

Objectives

To investigate whether income is associated with IHD in a middle-income country and whether neighborhood walkability mediates the income-IHD association.

Methods

This cross-sectional study evaluated 44,589 patients referred for myocardial perfusion imaging (SPECT-MPI). Income and walkability were derived from participants’ residential census tract. Walkability quantitative score combined 4 variables: street connectivity, residential density, commercial density, and mixed land use. IHD was defined by abnormal myocardial perfusion during a SPECT-MPI study. We used adjusted mixed effects models to evaluate the association between income level and IHD, and we performed a mediation analysis to measure the percentage of the income-IHD association mediated by walkability. We considered p values below 0.01 as statistically significant.

Results

From 26,415 participants, those living in the lowest-income tertile census tract were more physically inactive (79.1% versus 75.8% versus 72.7%) when compared to higher-income tertile census tracts (p < 0.001). Income was associated with IHD (odds ratio: 0.91 [95% confidence interval: 0.87 to 0.96] for each 1,000.00 international dollars increase in income) for both men and women equally (p for interaction = 0.47). Census tracts with a higher income were associated with better walkability (p < 0.001); however, walkability did not mediate the income-IHD association (percent mediated = −0.3%).

Conclusions

Income was independently associated with higher prevalence of IHD in a middle-income country irrespective of gender. Although walkability was associated with census tract income, it did not mediate the income-IHD association.

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Original Article

Relationship between the Fibrinogen/Albumin Ratio and Microvascular Perfusion in Patients Undergoing Primary Percutaneous Coronary Intervention for ST-Elevated Myocardial Infarction: A Prospective Study

Mustafa Kaplangoray et al. Kenan Toprak Omer Faruk Cicek Edhem Deveci

Abstract

Background

Correct TIMI frame count (CTFC), myocardial blush grade (MBG), and ST-segment resolution (STR) are parameters used to evaluate reperfusion at the microvascular level in patients that have undergone primary percutaneous coronary intervention (pPCI). Fibrinogen-to-albumin ratio (FAR) has been associated with thrombotic events in patients with ST-elevation myocardial infarction (STEMI) and chronic venous insufficiency.

Objectives

To investigate the relationship of FAR with CTFC, MBG, and STR. Methods: The study included 167 consecutive patients who underwent successful pPCI for STEMI and achieved TIMI-3 flow. The cases were divided into two groups, high (>0.0765) and low FAR (≤0.0765), according to the cut-off value of this parameter in the receiver operator characteristic analysis (ROC). STR, CTFC, and MBG were used to evaluate myocardial reperfusion. P values<0.05 were considered statistically significant.

Results

CTFC value, SYNTAX score, neutrophil/lymphocyte ratio, low-density lipoprotein, glucose, and peak cTnT were significantly higher, whereas STR, MBG, and LVEF were lower in the high FAR group. Spearman’s correlation analysis revealed a significant relationship between the FAR and STR (r=-0.666, p<0.001), MBG (-0.523, p28, and STR28 with a sensitivity of 76 % and a specificity of 65.8 %.

Conclusions

FAR is an important independent predictor of microvascular perfusion in patients undergoing pPCI for STEMI.

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ABCIC

Original Article

Incremental Determinants of The Combined Supine-Prone Protocol for Myocardial Perfusion Scintigraphy

Tiago Oliveira Costa et al. Mário de Seixas Rocha Gilson Feitosa Soares Filho Raphael Abegão de Camargo Cristiano Ricardo Bastos de Macedo

Abstract

Background:

Myocardial perfusion scintigraphy is an important non-invasive method for diagnosing coronary artery disease, but it is not free from artifacts. Performing the combined supine-prone protocol can bring benefits to images with artifacts from the standard protocol in the supine position. The lack of unanimity in the implementation of the combined protocol may be related to the lack of objective data for the prior selection of patients.

Objective:

To evaluate which anthropometric profiles may be associated with a greater benefit in excluding artifacts for the optimized performance of the combined protocol.

Methods:

A cross-sectional and analytical study was carried out with 370 patients at the Nuclear Medicine Group Clinic between April and August 2022. The estimated level of statistical significance was 5%. Statistical analysis using binary logistic regression was used to evaluate the association between anthropometric data and the change in the initial test result after carrying out the combined protocol.

Results:

The combined protocol promoted a 19.7% increase in the normality ratio of the standard protocol. The variables weight, for both genders [OR = 1.02 (95% CI, 1.0002 – 1.04; p = 0.047)], and bust in women [OR = 1.06 (95% CI, 1. 01 – 1.11; p = 0.014)] represented incremental determinants with statistical significance. Weight greater than 76.5kg for both genders (S: 58.5%; E: 61.5%) and bust greater than 100.0 cm in women (S: 73.9%; E: 53.4%) were the best cutoff points in the receiver operating characteristic (ROC) curve.

Conclusion:

The optimized implementation of the combined protocol using the described weight and bust measurement criteria can promote greater efficiency in image acquisition.

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Case Report

Evaluation of Coronary Flow Reserve by Myocardial Scintigraphy in Left Ventricular Hypertrophy

Renata Christian Martins Felix et al. Felipe Hermely Villela Pedras Odorico de Souza Lima Neto Leonardo Medeiros Vitório

Introduction

The microvascular integrity of the myocardial bed can be assessed by coronary flow reserve (CFR), which is a calculation of the ratio between the absolute coronary blood flow under vasodilator stress and under resting conditions. This measurement is capable of estimating vasomotor dysfunction, and it reflects the hemodynamic effect of focal, diffuse, or small-vessel coronary disease.

Currently, it is possible to measure CFR invasively using the techniques of thermodilution or intracoronary Doppler and through non-invasive methods, such as echocardiography, magnetic resonance imaging, computed tomography, or nuclear medicine.

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ABCIC

Brief Communication

The Importance of the Learning Curve in the Positive Predictive Value of Magnetic Resonance Myocardial Perfusion Imaging

Glauco Franco Santana et al. Thalles Oliveira Gomes Ana Carolina Ruela Vieira Onivaldo Pereira dos Santos

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ABCIC

Review Article

Applicability of Myocardial Perfusion Scintigraphy in the Evaluation of Cardiac Synchronization

Christiane Cigagna Wiefels Reis et al. Erivelton Alessandro do Nascimento Fernanda Baptista Ribeiro Dias Mario Luiz Ribeiro … Annelise Passos Bispo Wanderley Layanara Albino Batista Thais Helena Peixoto Nunes Claudio Tinoco Mesquita

Abstract

To systematically assess the literature on the applicability of myocardial perfusion scintigraphy with phase analysis in the investigation of cardiac dyssynchrony and in the selection of patients for cardiac resynchronization therapy (CRT), manuscripts published on the PubMed database over the past five years have been reviewed. The following MeSH terms were used: heart failure, left ventricular, dyssynchrony, gated-spect, phase analysis and resynchronization therapy. Altogether, 99 manuscripts were included for discussion. Speckle-tracking echocardiography is still widely used in the evaluation of dyssynchrony, but the advent of myocardial perfusion scintigraphy with the phase analysis technique has been gaining ground, as besides being operator-independent, it can evaluate myocardial viability in the same test. Its use became more widespread in patients with left bundle branch block, with recommendation of CRT. Phase analysis also allows evaluating, in a highly reproducible way, the last ventricular segment to contract, hence allowing the best positioning of the CRT electrode. Knowing that the presence, location and extent of fibrosis in the left ventricle, associated with dyssynchrony are determinants of response to resynchronization therapy, gated-SPECT can provide this information in a single test and in a reproducible and accurate way. Phase histogram offers several parameters that provide greater sensitivity and specificity to the method. It seems that the technique is able to add value both in the selection and in the evaluation of response of patients eligible to CRT. Further studies are being conducted to demonstrate its clinical applicability.

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IJCS

Original Article

Comparison between Bruce and Ramp Protocols for Exercise Testing in the Diagnosis of Myocardial Ischemia

Thiago Teixeira da Silveira Fagundes et al. Carolina Christianini Mizzaci Susimeire Buglia Fabricio da Costa Wohnrath … Flavia Medina João França Rica Dodo Delmar Buchler Luiz Eduardo Mastrocola Romeu Sérgio Meneghelo

Abstract

Background:

Exercise tests are an important tool in the investigation of myocardial ischemia. The ramp protocol has gained increasing importance in clinical practice because of the possibility of individualizing its exercise intensity.

Objective:

To assess and compare the sensitivity, specificity, and accuracy of Bruce and ramp protocols for exercise testing in the diagnosis of myocardial ischemia considering myocardial perfusion scintigraphy as the reference standard. Secondary objectives included the assessment of hemodynamic profiles, functional capacity, and the incidence of arrhythmias in each of the protocols.

Methods:

Participants underwent exercise testing using the ramp and Bruce protocols, and the tests’ diagnostic power was assessed. For testing the difference between data provided by both protocols, we used a paired Student’s t-test or Wilcoxon test, depending on the assumption of data normality. The level of significance adopted for all tests was 5%.

Results:

The ramp protocol showed sensitivity, specificity, and accuracy values of 55.6%, 82.4%, and 76.7%, respectively, whereas the Bruce protocol had results of 77.8%, 64.7%, and 67.4%, respectively. The maximum heart rate and double product at peak exercise were significantly higher in the Bruce protocol (p = 0.043 and p = 0.040, respectively). No differences were observed between the incidence of arrhythmias in both protocols.

Conclusion:

The Bruce protocol presented higher sensitivity for detecting ischemia on the exercise test, while the ramp protocol presented higher specificity and accuracy.

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Original Article

Does Tight Glucose Control During the First 24 hours of Hospitalization Reduce Scintigraphic Infarct Size in STEMI Patients?

Kamil Gulsen et al. Burak Ayca Murat Baskurt Baris Okcun Murat Kazim Ersanli

Abstract

Background

Hyperglycemia at the time of admission is related to increased mortality and poor prognosis in patients diagnosed with ST-segment elevation myocardial infarction (STEMI).

Objective

We aimed to investigate whether tight glucose control during the first 24 hours of STEMI decreases the scintigraphic infarct size.

Methods

The study population consisted of 56 out of 134 consecutive patients hospitalized with STEMI in a coronary care unit. Twenty-eight patients were treated with continuous insulin infusion during the first 24 hours of hospitalization, while the other 28 patients were treated with subcutaneous insulin on an as-needed basis. The final infarct size was evaluated with single-photon emission computed tomography (SPECT) in all patients on days 4 to 10 of hospitalization. The groups were compared and then predictors of final infarct size were analyzed with univariate and multivariate linear regression analysis. A p-value < 0.05 was considered statistically significant.

Results

The mean glucose level in the first 24 hours was 130 ± 20 mg/dL in the infusion group and 152 ± 31 mg/dL in the standard care group (p = 0.002), while the mean final infarct size was 20 ± 12% and 27 ± 15% (p = 0.06), respectively. The multivariate linear regression analysis demonstrated that the mean 24-hour glucose level was an independent predictor of the final infarct size (beta 0.29, p = 0.026).

Conclusion

Tight glucose control with continuous insulin infusion was not associated with smaller infarct size when compared to standard care in STEMI patients. (Int J Cardiovasc Sci. 2020; [online].ahead print, PP.0-0)

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Editorial

Myocardial Computed Tomography Perfusion: One More Piece on The Board

Gabriel Blacher Grossman

The most appropriate way to evaluate patients with stable coronary artery disease (CAD) and the subsequent definition of the therapeutic approach has been the subject of debate in recent years. For several years the anatomical evaluation was considered sufficient to indicate myocardial revascularization. The emergence of several methods of non-invasive functional evaluation in clinical practice as well as data from observational studies demonstrating that there is a level of ischemia above which a revascularization strategy might result in benefit regarding cardiovascular events raised doubts whether an strategy based in coronary anatomic findings was the best option.^, This questioning changed the paradigm of CAD evaluation. Although randomized clinical trials have failed to demonstrate that the extent of ischemia can determine which patients would benefit from a revascularization strategy,^– the fact that the presence of moderate to severe ischemia is undeniably a marker of cardiovascular risk has lead functional evaluation to become a fundamental part in the management of patients with stable CAD.

In this context, Ker et al. in this edition of the Arquivos Brasileiros de Cardiologia evaluated 35 patients undergoing a simultaneous pharmacologic stress protocol of myocardial perfusion evaluation by computed tomography angiography (angio-CT) and single-photon emission computed tomography (SPECT) and compared the sensitivity of the methods using the presence of obstructive lesion evidenced by angio-CT greater than 50% as the gold standard for the presence of significant CAD.

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Original Article

Myocardial Perfusion by Coronary Computed Tomography in the Evaluation of Myocardial Ischemia: Simultaneous Stress Protocol with SPECT

Wilter dos Santos Ker et al. Daniel Gama das Neves Tiago Augusto Magalhães Alair Augusto Sarmet M. D. dos Santos … Claudio Tinoco Mesquita Marcelo Souto Nacif

Abstract

Background:

Functional assessment to rule out myocardial ischemia using coronary computed tomography angiography (CCTA) is extremely important and data on the Brazilian population are still limited.

Objective:

To assess the diagnostic performance of myocardial perfusion by CCTA in the detection of severe obstructive coronary artery disease (CAD) compared with single-photon emission computerized tomography (SPECT). To analyze the importance of anatomical knowledge to understand the presence of myocardial perfusion defects on SPECT imaging that is not identified on computed tomography (CT) scan.

Method:

A total of 35 patients were evaluated by a simultaneous pharmacologic stress protocol. Fisher’s exact test was used to compare proportions. The patients were grouped according to the presence or absence of significant CAD. The area under the ROC curve was used to identify the diagnostic performance of CCTA and SPECT in perfusion assessment. P < 0.05 values were considered statistically significant.

Results:

For detection of obstructive CAD, CT myocardial perfusion analysis yielded an area under the ROC curve of 0.84 [a 95% confidence interval (CI95%): 0.67-0.94, p < 0.001]. SPECT myocardial perfusion imaging, on the other hand, showed an AUC of 0.58 (95% CI 0.40 – 0.74, p < 0.001). In this study, false-positive results with SPECT are described.

Conclusion:

Myocardial perfusion analysis by CTA displays satisfactory results compared to SPECT in the detection of obstructive CAD. CCTA can rule out false-positive results of SPECT.

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Letter to the Editor

Comment on Myocardial Perfusion Study in Obese Patients without Known Cardiac Ischemia

Claudio Tinoco Mesquita et al. Gustavo Gavina da Cruz

We congratulate Dippe et al. for their work that addressed the role of myocardial scintigraphy in the diagnosis of myocardial ischemia in obese patients. Despite limitations, body mass index (BMI) has been the most used anthropometric tool for assessing nutritional status in adults. Epidemiologic studies have identified high BMI as a risk factor for an expanding set of chronic diseases, including cardiovascular disease and diabetes mellitus. The Global Burden of Disease (GBD) Obesity Collaborators found that excess body weight accounted for about 4 million deaths in 2015. Nearly 70% of these deaths were due to cardiovascular disease, and more than 60% of them occurred among obese persons (BMI ≥ 30 Kg/m²). The use of a database of consecutive patients provides a sample of obese patients from the real-world scenario and portrays the current clinical practice in which the cardiologist faces major diagnostic challenges in obese patients. All diagnostic methods have significant challenges in obese patients such as the limitation of the acoustic window in the echocardiogram, higher incidence of photon attenuation on computed tomography and myocardial scintigraphy and bore size limitations to cardiac resonance imaging. Radiation-sparing techniques are more difficult to use in heavier patients. The finding that clinical data such as the presence of diabetes mellitus, older age and typical symptoms of angina highlights the need of careful clinical evaluation in order to adequate request ischemic screening tests in patients with suspected coronary artery disease, especially in the obese. Another important finding of their study was the absence of association between obesity alone, especially in the group with BMI greater than 40, with the presence of ischemia. A technical aspect that was not clear in the article and whether the authors used the prone acquisition when there was doubt about the presence of breast attenuation and also the technique used to quantify the visual or automatic ischemia.

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IJCS

Case Report

Left Ventricular Dyssynchrony in a Patient with Normal Perfusion and Stress-Induced Left Bundle Branch Block

Maria Gazzilli et al. Rexhep Durmo Claudio Tinoco Mesquita Raffaele Giubbini

Introduction

Left bundle branch block (LBBB) is an electrocardiographic abnormality that occurs in approximately 0.5-1.1% of all patients who undergo exercise testing. The diagnosis of complete LBBB is made with the 12-lead electrocardiogram (ECG) if all the following criteria are met: conduction originating above the atrioventricular node; a QRS duration of 120 milliseconds or more; predominantly upright complexes with broad-slurred R waves in leads I, V5, and V6; and a QS or RS pattern in V1 with a normal intrinsicoid deflection of 35 milliseconds.

The precise mechanism and the prognostic significance of Exercise Induced-LBBB (EI-LBBB) remains unclear. EI-LBBB can be associated with coronary artery disease (CAD). However, in a group of patients, coronary arteries are normal. Several authors have attributed EI-LBBB to functional alterations of the conduction system mediated by autonomic influences in non-ischemic cases. We report a case of a 72-year-old female patient who developed LBBB during exercise stress testing and showed reversible abnormalities in cardiac contraction.

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Case Report

Quantification of Coronary Flow Reserve with CZT Gamma Camera in the Evaluation of Multivessel Coronary Disease

Ana Carolina do Amaral Henrique de Souza et al. Bernardo Kremer Diniz Gonçalves Angelo Tedeschi Ronaldo de Souza Leão Lima

Introduction

Evaluating patients with multivessel coronary disease using myocardial perfusion scintigraphy (MPS) remains a challenge as the extent and severity of the disease can be underestimated. This phenomenon occurs in part due to balanced ischemia and inaccuracy of traditional devices to identify small changes in coronary flow in the stress phase.^, New gamma cameras with cadmium and zinc telluride (CZT) detectors that are already commercially available have shown higher temporal and spatial resolution,^– theoretically enabling dynamic acquisition of images and calculation of myocardial blood flow (MBF) and coronary flow reserve (CFR) in an absolute way.^, This tool, whose use with positron emission tomography (PET) is already well established,^– may be promising to non invasively access three-vessel obstructive coronary artery disease (CAD) using scintigraphy and its conventional radiotracers. The objective of this case report is to describe the quantification of CFR upon diagnosis of a patient with multivessel disease whose myocardial perfusion image showed a defect not compatible with coronary angiography.

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Original Article

Current Practices in Myocardial Perfusion Scintigraphy in Brazil and Adherence to the IAEA Recommendations: Results of a Cross-Sectional Study

Carlos Vitor Braga Rodrigues et al. Anderson Oliveira Christiane Cigagna Wiefels Maurício de Souza Leão Cláudio Tinoco Mesquita

Abstract

Background:

Data on the current situation of nuclear medicine practices in cardiology in Brazil are scarce. The International Atomic Energy Agency (IAEA) has recommended eight “good practices” to minimize patients’ ionizing radiation exposure during myocardial perfusion scintigraphy (MPS).

Objectives:

To assess the adoption of the eight good practices in MPS in Brazil.

Methods:

Cross-sectional study with data obtained by use of a questionnaire. All hypothesis tests performed considered a significance level of 5%.

Results:

We observed that 100% of the nuclear medicine services (NMS) assessed do not use thallium-201 as the preferred protocol. Regarding the use of technetium-99m, 57% of the NMS administer activities above the threshold recommended by the IAEA (36 mCi) or achieve an effective dose greater than 15 millisievert (mSv). The abbreviated stress-only myocardial perfusion imaging is not employed by 94% of the NMS; thus, only 19% count on strategies to reduce the radioactive doses. Approximately 52% of the NMS reported always performing dose adjustment for patient’s weight, while 35% administer poorly calculated doses in the one-day protocol.

Conclusion:

A considerable number of NMS in Brazil have not adopted at least six practices recommended by the IAEA. Despite the difficulties found in nuclear practice in some Brazilian regions, almost all obstacles observed can be overcome with no cost increase, emphasizing the importance of developing strategies for adopting “good practices” when performing MPS.

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Case Report

Case Report: Multivessel Coronary Disease Assessment with SPECT 99mTc-Sestamibi and Rubidium-82 PET/CT

Bruno Gomes Padilha et al. Daniela Sabino Maria Clementina Giorgi José Soares Jr. … Marisa Izaki José Claudio Meneghetti

Introduction

Coronary angiography (CAG) is the standard diagnostic method for detection of coronary artery disease (CAD). However, it is often necessary to evaluate the expression of a coronary obstruction in relation to myocardial perfusion, before defining the best patient management.

Myocardial perfusion scintigraphy with technetium-99m-Sestamibi (^99mTc-sestamibi) allows early detection and evaluation of disease extension and cardiovascular risk in patients with suspected or established CAD, helping in decision-making regarding the start and type of therapy to be implemented. This method has been widely used, but shows difficulties in some situations such as balanced multivessel disease, in which the proportional flow distribution in the myocardial regions can hinder ischemia detection. In such cases, additional assessment data, such as evaluation of contractility, decrease in left ventricular ejection fraction (LVEF) under stress, electrocardiographic alterations or symptoms during stress, dilation of the left ventricle (LV) cavity under stress can provide evidence of ischemia, indicating further diagnostic investigation.

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Original Article

Dipyridamole stress myocardial perfusion by computed tomography in patients with left bundle branch block

Estêvan Vieira Cabeda et al. Andréa Maria Gomes Falcão José Soares Jr. Carlos Eduardo Rochitte … César Higa Nomura Luiz Francisco Rodrigues Ávila José Rodrigues Parga

Abstract

Background:

Functional tests have limited accuracy for identifying myocardial ischemia in patients with left bundle branch block (LBBB).

Objective:

To assess the diagnostic accuracy of dipyridamole-stress myocardial computed tomography perfusion (CTP) by 320-detector CT in patients with LBBB using invasive quantitative coronary angiography (QCA) (stenosis ≥ 70%) as reference; to investigate the advantage of adding CTP to coronary computed tomography angiography (CTA) and compare the results with those of single photon emission computed tomography (SPECT) myocardial perfusion scintigraphy.

Methods:

Thirty patients with LBBB who had undergone SPECT for the investigation of coronary artery disease were referred for stress tomography. Independent examiners performed per-patient and per-coronary territory assessments. All patients gave written informed consent to participate in the study that was approved by the institution’s ethics committee.

Results:

The patients’ mean age was 62 ± 10 years. The mean dose of radiation for the tomography protocol was 9.3 ± 4.6 mSv. With regard to CTP, the per-patient values for sensitivity, specificity, positive and negative predictive values, and accuracy were 86%, 81%, 80%, 87%, and 83%, respectively (p = 0.001). The per-territory values were 63%, 86%, 65%, 84%, and 79%, respectively (p < 0.001). In both analyses, the addition of CTP to CTA achieved higher diagnostic accuracy for detecting myocardial ischemia than SPECT (p < 0.001).

Conclusion:

The use of the stress tomography protocol is feasible and has good diagnostic accuracy for assessing myocardial ischemia in patients with LBBB.

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Original Article

BNP was Associated with Ischemic Myocardial Scintigraphy and Death in Patients at Chest Pain Unit

Jader Cunha de Azevedo et al. Bruno Cezario Costa Reis Nathalia Monerat P.B. Barreto Diogenes S. F. Junior … Lais S. Prezotti Victor Rebelo Procaci Vivian Werneck Octaviano Andre Volschan Evandro Tinoco Mesquita Claudio Tinoco Mesquita

Background:

Recent studies have suggested that B-type Natriuretic Peptide (BNP) is an important predictor of ischemia and death in patients with suspected acute coronary syndrome. Increased levels of BNP are seen after episodes of myocardial ischemia and may be related to future adverse events.

Objectives:

To determine the prognostic value of BNP for major cardiac events and to evaluate its association with ischemic myocardial perfusion scintigraphy (MPS).

Methods:

This study included retrospectively 125 patients admitted to the chest pain unit between 2002 and 2006, who had their BNP levels measured on admission and underwent CPM for risk stratification. BNP values were compared with the results of the MPS. The chi-square test was used for qualitative variables and the Student t test, for quantitative variables. Survival curves were adjusted using the Kaplan-Meier method and analyzed by using Cox regression. The significance level was 5%.

Results:

The mean age was 63.9 ± 13.8 years, and the male sex represented 51.2% of the sample. Ischemia was found in 44% of the MPS. The mean BNP level was higher in patients with ischemia compared to patients with non-ischemic MPS (188.3 ± 208.7 versus 131.8 ± 88.6; p = 0.003). A BNP level greater than 80 pg/mL was the strongest predictor of ischemia on MPS (sensitivity = 60%, specificity = 70%, accuracy = 66%, PPV = 61%, NPV = 70%), and could predict medium-term mortality (RR = 7.29, 95% CI: 0.90-58.6; p = 0.045) independently of the presence of ischemia.

Conclusions:

BNP levels are associated with ischemic MPS findings and adverse prognosis in patients presenting with acute chest pain to the emergency room, thus, providing important prognostic information for an unfavorable clinical outcome.

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Original Article

Applicability of the Appropriate use Criteria for Myocardial Perfusion Scintigraphy

Anderson de Oliveira et al. Maria Fernanda Rezende Renato Corrêa Rodrigo Mousinho … Jader Cunha Azevedo Sandra Marina Miranda Aline Ribeiro Oliveira Ricardo Fraga Gutterres Evandro Tinoco Mesquita Cláudio Tinoco Mesquita

Background:

Appropriateness Criteria for nuclear imaging exams were created by American College of Cardiology (ACC) e American Society of Nuclear Cardiology (ASNC) to allow the rational use of tests. Little is known whether these criteria have been followed in clinical practice.

Objective:

To evaluate whether the medical applications of myocardial perfusion scintigraphy (MPS) in a private nuclear medicine service of a tertiary cardiology hospital were suitable to the criteria of indications proposed by the American medical societies in 2005 and 2009 and compare the level of indication of both.

Methods:

We included records of 383 patients that underwent MPS, November 2008 up to February 2009. Demographic characteristics, patient’s origin, coronary risk factors, time of medical graduation and appropriateness criteria of medical applications were studied. The criteria were evaluated by two independent physicians and, in doubtful cases, defined by a medical expert in MPS.

Results:

Mean age was 65 ± 12 years. Of the 367 records reviewed, 236 (64.3%) studies were performed in men and 75 (20.4%) were internee. To ACC 2005, 255 (69.5%) were considered appropriate indication and 13 (3.5%) inappropriate. With ACC 2009, 249 (67.8%) were considered appropriate indications and 13 (5.2%) inappropriate.

Conclusions:

We observed a high rate of adequacy of medical indications for MPS. Compared to the 2005 version, 2009 did not change the results.

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