Improving Outcomes in Ventricular Tachycardia Ablation Using Imaging to Identify Arrhythmic Substrates.

Ventricular tachycardia (VT) ablation is limited by modest acute and long-term success rates, in part due to the challenges in accurately identifying the arrhythmogenic substrate. The combination of multimodality imaging along with information from electroanatomic mapping allows for a more comprehensive assessment of the arrhythmogenic substrate which facilitates VT ablation, and the use of preprocedural imaging has been shown to improve long-term ablation outcomes. Beyond regional recognition of the arrhythmogenic substrate, advanced imaging techniques can be used to create tailored ablation strategies preprocedurally. This review will focus on how imaging can be used to guide ablation planning and execution with a focus on clinical applications aimed at improving the outcome of VT ablation procedures.

Nuclear Cardiac Imaging in the Interventional Suite.

PURPOSE OF REVIEW: This review presents the current state of imaging approaches that enable real-time molecular imaging in the interventional suite and discusses the potential future use of integrated nuclear imaging and fluoroscopy for intraprocedural guidance in the evaluation and treatment of both cardiovascular and oncological diseases. RECENT FINDINGS: Although there are no commercially available real-time hybrid nuclear imaging devices that are approved for use in the interventional suite, prototype open gantry hybrid nuclear imaging and x-ray c-arm imaging systems and theranostic catheter for location radiotracer detection are currently undergoing development and testing by multiple groups. The integration of physiological and molecular targeted nuclear imaging for real-time delivery of targeted theranostics in the interventional laboratory may enable more personalized care for a wide variety of cardiovascular procedures and improve patient outcomes.

Left ventricular mass on positron emission tomography: Validation against cardiovascular magnetic resonance.

BACKGROUND: Left ventricular hypertrophy (LVH) is an important clinical finding that is independently associated with mortality and cardiovascular events. We aimed to assess the interstudy variability of LV mass quantitation between PET and CMR. METHODS: Patients who underwent both PET and CMR within 1 year were identified from prospective institutional registries. LV mass on PET was compared against LV mass on CMR using several statistical measures of agreement. RESULTS: A total of 105 patients (mean age 60 ± 14 years, 67.6% male) were included. The median (interquartile range, IQR) duration between CMR and PET was 47 (11-154) days. The median (IQR) LV mass values were 168.0 g (126.0-202.0) on CMR and 174.0 g (150.0-212.0) with PET (absolute mean difference 29.42 ± 25.3). There was a good correlation (Spearman ρ = 0.81, P < 0.001; Intraclass Correlation Coefficient 0.78, 95% CI 0.70-0.85, P < 0.001) with moderate limits of agreement (95% limits of agreement - 63.78 to 83.7.) Results were consistent, albeit with moderate correlation, in subgroups of patients with LVH, in patients with myocardial infarction, in patients with LV ejection fraction < 50%, and those with limited image quality. LV mass on PET tended to be underestimated at high values compared to CMR. CONCLUSION: We demonstrate good correlation and reproducibility of LV mass quantitation by PET against the reference standard of CMR across a wide range of normal and diseased hearts with a tendency of PET to underestimate mass at higher mass values.

The prognostic role of cardiac positron emission tomography imaging in patients with sarcoidosis: A systematic review.

PURPOSE: Sarcoidosis is a multi-systemic inflammatory disease of unknown etiology. Cardiac sarcoidosis (CS) has been reported in as much as 25% of patients with systemic involvement. 18Fluorodeoxyglucose (FDG) positron emission tomography (PET) has a high diagnostic sensitivity/specificity in the diagnosis of CS. The aim of this review is to summarize evidence on the prognostic role of FDG PET. METHODS: Studies were identified by searching MEDLINE from inception to October 2020. Medical subject headings (MeSH) terms for sarcoidosis; cardiac and FDG PET imaging were used. Studies of any design assessing the prognostic role of FDG PET in patients with either suspected or confirmed cardiac sarcoidosis imaging done at baseline were included. Abnormal PET was defined as abnormal metabolism (presence of focal or focal-on-diffuse uptake of FDG) OR abnormal metabolism and a perfusion defect. Studies reporting any outcome measure were included. Pooled risk ratio for the composite outcome of MACE was done. RESULTS: A total of 6 studies were selected for final inclusion (515 patients, 53.4% women, 19.8% racial minorities.) Studies were institution based, retrospective in design and enrolled consecutive patients. All were observational in nature and published in English. All studies used a qualitative assessment of PET scans (abnormal FDG uptake with or without abnormal perfusion). Two studies assessed quantitative metrics (summed stress score in segments with abnormal FDG uptake, standardized uptake value and cardiac metabolic activity.) All studies reported major adverse cardiovascular events (MACE) as a composite outcome. After a mean follow up ranging from 1.4 to 4.1 years, there were a total of 105 MACE. All studies included death (either all-cause death or sudden cardiac death) and ventricular arrhythmia (ventricular tachycardia or ventricular fibrillation) as a component of MACE. Four of the six studies adjusted for several characteristics in their analysis. All four studies used left ventricular ejection fraction (LVEF). However, other adjustment variables were not consistent across studies. Five studies found a positive prognostic association with the primary outcome, two of which assessing right ventricular uptake. CONCLUSION: Although available evidence indicates FDG PET can be used in the risk stratification of patients with CS, our findings show further studies are needed to quantify the effect in this patient group.

Nuclear cardiology: state of the art.

Radionuclide imaging remains an essential component of modern cardiology. There is overlap with the information from other imaging techniques, but no technique is static and new developments have expanded its role. This review focuses on ischaemic heart disease, heart failure, infection and inflammation. Radiopharmaceutical development includes the wider availability of positron emission tomography (PET) tracers such as rubidium-82, which allows myocardial perfusion to be quantified in absolute terms. Compared with alternative techniques, myocardial perfusion scintigraphy PET and single photon emission computed tomography (SPECT) have the advantages of being widely applicable using exercise or pharmacological stress, full coverage of the myocardium and a measure of ischaemic burden, which helps to triage patients between medical therapy and revascularisation. Disadvantages include the availability of expertise in some cardiac centres and the lack of simple SPECT quantification, meaning that global abnormalities can be underestimated. In patients with heart failure, despite the findings of the STICH (Surgical Treatment for Ischemic Heart Failure) trial, there are still data to support the assessment of myocardial hibernation in predicting when abolition of ischaemia might lead to improvement in ventricular function. Imaging of sympathetic innervation is well validated, but simpler markers of prognosis mean that it has not been widely adopted. There are insufficient data to support its use in predicting the need for implanted devices, but non-randomised studies are promising. Other areas where radionuclide imaging is uniquely valuable are detection and monitoring of endocarditis, device infection, myocardial inflammation in sarcoidosis, myocarditis and so on, and reliable detection of deposition in suspected transthyretin-related amyloidosis.

Prevalence and clinical outcomes of triglyceride deposit cardiomyovasculopathy among haemodialysis patients.

OBJECTIVE: To evaluate the effect of triglyceride deposit cardiomyovasculopathy (TGCV) on the cardiovascular outcomes in haemodialysis (HD) patients with suspected coronary artery disease (CAD). METHODS: This retrospective single-centre observational study included data from the cardiac catheter database of Narita Memorial Hospital between April 2011 and March 2017. Among 654 consecutive patients on HD, the data for 83 patients with suspected CAD who underwent both [123I]-ß-methyl-iodophenyl-pentadecanoic acid scintigraphy and coronary angiography were analysed. Patients were divided into three groups: definite TGCV (17 patients), probable TGCV (22 patients) and non-TGCV control group (44 patients). The primary endpoint was a composite of cardiovascular death, non-fatal myocardial infarction and non-fatal stroke assessed for up to 5 years of follow-up. RESULTS: The prevalence of definite TGCV was approximately 20% and 2.6% among consecutive HD patients with suspected CAD and among all HD patients, respectively. At the end of the median follow-up period of 4.7 years, the primary endpoint was achieved in 52.9% of the definite TGCV patients (HR, 7.45; 95% CI: 2.28 to 24.3; p<0.001) and 27.3% of the probable TGCV patients (HR, 3.28; 95% CI: 0.93 to 11.6; p=0.066), compared with that in 9.1% of the non-TGCV control patients. Definite TGCV was significantly and independently associated with cardiovascular mortality and outcomes among HD patients in all multivariate models. CONCLUSIONS: TGCV is not uncommon in HD patients and is associated with an increased risk of cardiovascular events including cardiovascular death. Thus, TGCV might be a potential therapeutic target.

Positron emission tomography imaging in cardiovascular disease.

Positron emission tomography (PET) imaging is useful in cardiovascular disease across several areas, from assessment of myocardial perfusion and viability, to highlighting atherosclerotic plaque activity and measuring the extent of cardiac innervation in heart failure. Other important roles of PET have emerged in prosthetic valve endocarditis, implanted device infection, infiltrative cardiomyopathies, aortic stenosis and cardio-oncology. Advances in scanner technology, including hybrid PET/MRI and total body PET imaging, as well as the development of novel PET tracers and cardiac-specific postprocessing techniques using artificial intelligence will undoubtedly continue to progress the field.

Applications of artificial intelligence in multimodality cardiovascular imaging: A state-of-the-art review.

There has been a tidal wave of recent interest in artificial intelligence (AI), machine learning and deep learning approaches in cardiovascular (CV) medicine. In the era of modern medicine, AI and electronic health records hold the promise to improve the understanding of disease conditions and bring a personalized approach to CV care. The field of CV imaging (CVI), incorporating echocardiography, cardiac computed tomography, cardiac magnetic resonance imaging and nuclear imaging, with sophisticated imaging techniques and high volumes of imaging data, is primed to be at the forefront of the revolution in precision cardiology. This review provides a contemporary overview of the CVI imaging applications of AI, including a critique of the strengths and potential limitations of deep learning approaches.

Non-cardiac uptake of technetium-99m pyrophosphate in transthyretin cardiac amyloidosis.

BACKGROUND: Technetium-based bone scintigraphy is rapidly becoming the most common non-invasive imaging tool in the diagnosis of Transthyretin cardiac amyloidosis (ATTR). Skeletal muscle uptake has been described with technetium-99m-3,3-diphosphono-1,2-propanodicarboxylic acid (TcDPD), and may account for masking of bony uptake. We sought to investigate skeletal muscle uptake of technetium-99m-pyrophosphate (TcPYP) in patients with ATTR. METHODS AND RESULTS: This was a retrospective analysis of 57 patients diagnosed with ATTR who underwent TcPYP scintigraphy. Cardiac uptake was assessed on whole-body planar imaging using a semiquantitative scale (grades 0 to 3) and on single-photon emission computed tomography (SPECT) with CT attenuation correction using total myocardial counts per voxel after a 3-hour incubation. Skeletal muscle (psoas and biceps), vertebral body, LV myocardium, and blood pool mean counts were calculated. In the cohort (age 78 ± 9 years, 77% male, and 30% hereditary ATTR), there was no visualized tracer uptake in skeletal muscle or soft tissue on qualitative SPECT assessment. Total and blood pool-corrected uptake in the muscle groups were significantly less than myocardium and bone (P < 0.001). Blood pool-corrected muscle uptake was not associated with semiquantitative grade 3 vs 2 uptake (psoas P = 0.66, biceps P = 0.13) or presence of hereditary ATTR (psoas P = 0.43, biceps P = 0.69). As bony uptake decreased, there was no corresponding increase in skeletal muscle uptake. CONCLUSIONS: In patients with ATTR cardiac amyloidosis, skeletal muscle uptake of TcPYP is minimal when assessed by qualitative and quantitative metrics, and is not significantly different in patients with grade 2 vs 3 semiquantitative uptake. The properties of this tracer may be different than TcDPD with respect to non-cardiac uptake.

Cardiovascular imaging in cardio-oncology.

Cancer therapy may lead to cardiovascular complications and can promote each aspect of cardiac disease manifestation, such as vascular disease including coronary heart disease, myocardial diseases including heart failure, structural heart diseases including valvular heart diseases, and rhythm disorders. All potential complications of cancer therapy onto the cardiovascular system require imaging for diagnostic workup as well as monitoring of therapy. Transthoracic echocardiography (TTE) is the most frequently used tool for assessment of cardiac function during or after cancer therapy in daily clinical routine. With modern techniques like strain analysis, echocardiography allows to detect a variety of cardiac diseases as caused by cancer therapy even at subclinical stages. For further workup, specific imaging techniques including nuclear imaging are needed in a multimodality imaging approach to in detail characterize the underlying pathophysiology and to improve the management of the patients. Therefore, the field of imaging in cardio-oncology is rapidly growing. This review article will give an overview about existing literature regarding the role of imaging in the diagnostic evaluation and management of therapy in patient with prior or ongoing cancer therapy.

Regional Variation in Technetium Pyrophosphate Uptake in Transthyretin Cardiac Amyloidosis and Impact on Mortality.

OBJECTIVES: This study sought to investigate the regional uptake of technetium 99m-pyrophosphate (TcPYP) in transthyretin cardiac amyloidosis (ATTR) and its association with mortality. BACKGROUND: TcPYP nuclear scintigraphy is a diagnostic and prognostic tool in ATTR. Echocardiography has identified a pattern of regional variation in longitudinal strain (LS) with a gradient of improved strain from base to apex in ATTR. METHODS: Consecutive patients with ATTR were evaluated who underwent TcPYP nuclear scintigraphy with planar and attenuation corrected single-photon emission computed tomography (SPECT). Heart-to-contralateral lung (H/CL) ratio was calculated on planar images, and left ventricular (LV) uptake was determined in each of the 17 segments using SPECT. A measure of apical-sparing of myocardial TcPYP uptake, termed the apical-sparing ratio (ASR), was calculated as basal + mid / apical counts. RESULTS: Overall, 54 patients with ATTR (age 78 ± 9 years, 76% male, 31% hereditary ATTR) were analyzed. There was increased TcPYP uptake in basal and mid relative to apical LV segments, and an apical-sparing LS pattern on echocardiography. The right ventricle similarly showed greater uptake in basal segments. There were 26 deaths over 1.8 years median follow-up. The ASR of TcPYP uptake was associated with age-adjusted all-cause mortality (p = 0.013) with worse prognosis seen at levels <2.75. Global LS was also prognostic (p = 0.01), whereas H/CL ratio and total LV uptake indexed to blood pool were not (p = 0.772 and p = 0.850, respectively). The prognostic utility of the ASR persisted in multivariable modeling (p = 0.003), whereas global LS did not. CONCLUSIONS: There is decreased TcPYP uptake in apical as compared to mid and basal segments in the LV, mimicking apical-sparing LS seen on echocardiography. Regional distribution of LV TcPYP uptake is associated with mortality, whereas overall amount of uptake as measured by H/CL ratio and indexed LV SPECT uptake is not.

Role of cardiovascular magnetic resonance in the management of patients with stable coronary artery disease.

Cardiovascular magnetic resonance (CMR) assesses cardiac function, ischaemia, viability and tissue characterisation, all within a single scan. Many studies regarding the role of CMR in stable coronary artery disease (CAD) have been published over the last decade providing important technical advances, large-scale clinical validation and prognostic data. As a result, CMR has emerged as a highly accurate technique for diagnosis and risk stratification in stable CAD and has been incorporated into national and international guidelines. Furthermore, clinical pathways utilising CMR have been shown to be the most cost-effective in several healthcare systems. In this review, we summarise the key roles and guideline recommendations for CMR in stable CAD supported by contemporary clinical evidence.

In vivo quantification of amyloid burden in TTR-related cardiac amyloidosis.

Cardiac transthyretin-related (ATTR) amyloidosis is a severe cardiomyopathy for which therapeutic approaches are currently under development. Because non-invasive imaging techniques such as cardiac magnetic resonance imaging and echocardiography are non-specific, the diagnosis of ATTR amyloidosis is still based on myocardial biopsy. Thus, diagnosis of ATTR amyloidosis is difficult in patients refusing myocardial biopsy. Furthermore, myocardial biopsy does not allow 3D-mapping and quantification of myocardial ATTR amyloid. In this report we describe a 99mTc-DPD-based molecular imaging technique for non-invasive single-step diagnosis, three-dimensional mapping and semiquantification of cardiac ATTR amyloidosis in a patient with suspected amyloid heart disease who initially rejected myocardial biopsy. This report underlines the clinical value of SPECT-based nuclear medicine imaging to enable non-invasive diagnosis of cardiac ATTR amyloidosis, particularly in patients rejecting biopsy.

Nuclear cardiology in China: 2017.

This paper provides the current state of nuclear cardiology in China and contrasts it with the state of nuclear cardiology in the United States (US). The West China Hospital and New York-Presbyterian Hospital (NYPH) were used as representative hospitals to contrast nuclear cardiology in China and the US, respectively. In 2015, there were 101 medical cyclotrons, 774 SPECT or SPECT/CT, 240 PET/CT, and 6 PET/MR cameras in China. Most (~90%) of the nuclear cardiology studies are gated SPECT myocardial perfusion imaging (MPI), and ~10% are other types of studies including MUGA, PET/CT MPI, and viability studies. There are differences in nuclear cardiology between the West China Hospital and NYPH and these include those in cardiac stress tests, SPECT/CT acquisition protocols, PET/CT blood flow and viability studies, reimbursement, and fellowship training. In this paper, we aim to present status of nuclear cardiology in China and provide potential solutions.