Radionuclide Imaging of Cardiac Amyloidosis: An Update and Future Aspects.

Cardiac amyloidosis (CA) is caused by the misfolding, accumulation and aggregation of proteins into large fibrils in the extracellular compartment of the myocardium, leading to restrictive cardiomyopathy, heart failure and death. The major forms are transthyretin (ATTR) CA and light-chain (AL) CA, based on the respective precursor protein. Each of them requires early diagnosis for a timely treatment initiation that will improve patient outcomes. For this, radionuclide imaging is essentially used as single-photon emission computed tomography (SPECT) with bone-avid radiotracers or as positron emission tomography (PET) with amyloid-binding radiotracers. Both offer unprecedented specificity for the diagnostic of CA. SPECT has even revolutionized the diagnosis of ATTR-CA by making it non-invasive. Indeed, SPECT has now entered the standard diagnostic pathway to CA and has led to earlier diagnosis of the disease. SPECT also modified the epidemiology of ATTR-CA, highlighting that the disease is much more frequent than previously believed, and showing that ATTR-CA plays a substantial role in HFpEF and aortic stenosis, particularly among elderly patients. In parallel, amyloid-binding radiotracers for PET have accumulated a substantial amount of evidence, but are not approved for clinical use in CA yet. Further studies are needed to refine acquisition protocols and validate results in broader populations. Unlike bone-avid SPECT radiotracers, PET radiotracers have been specifically created to bind to amyloid fibrils. Thus, PET is the only imaging method that is truly specific for amyloid deposits and very sensitive to any amyloid type. Indeed, PET can not only detect ATTR-CA, but also AL-CA and rare hereditary forms. For both SPECT and PET, advances in quantitation of myocardial uptake have generated more granular and reproducible findings, paving the way for progress in earlier diagnosis, risk stratification and therapeutic response monitoring. Encouraging findings have shown that SPECT and PET are sensitive to early CA when other diagnostic methods are negative. Both radionuclide imaging techniques can predict adverse outcomes, but more evidence is needed to determine how to use them in conjunction with usual prognostic staging scores. Studies on follow-up imaging after therapy suggested that SPECT and PET can capture myocardial changes in CA, but again, more data are needed to meaningfully interpret such changes. Based on all these promising results, radionuclide imaging has the potential to further impact the landscape of CA in diagnosis, prognosis and follow-up, but also to substantially contribute to the assessment of novel therapies that will improve the lives of patients with CA.

Multivariate curve resolution -alternating least squares augmented with partial least squares baseline correction applied to mid-IR laser spectra resolves protein denaturation by reducing rotational ambiguity.

High spectral power density provided by advances in external cavity quantum cascade lasers (EC-QCL) have enabled increased transmission path lengths in mid-infrared (mid-IR) spectroscopy for more sensitive measurement of proteins in aqueous solutions. These extended path lengths also facilitate flow through measurements by avoiding congestion of the flow cell by protein aggregates. Despite the advantages presented by laser-based mid-IR spectroscopy of proteins, extraction of secondary structure information from spectra, especially in the presence of complex multi-component matrices with overlapping spectral features, remains an impediment that requires fine tuning of evaluation algorithms (e.g., band fitting, interpretation of second derivative spectra etc.). In this work, the use of multivariate curve resolution alternating least squares (MCR-ALS) for the analysis of a chemical de- and renaturation experiment has been demonstrated, since this technique offers the second-order advantage of extracting spectral signatures and concentration profiles even in the presence of unknown, uncalibrated constituents. Furthermore, we exhibit a partial least squares regression (PLSR) based subtraction of matrix component spectra prior to MCR-ALS as a method to obtain secondary structure information even in the absence of reference spectra. These approaches are showcased using the online reaction monitoring of the titration of ß-lactoglobulin (ß-LG) in water against the surfactants sodium dodecyl sulfate (SDS) and octaethylene glyol monododecyl ether (C12E8), using a commercially available laser-based IR spectrometer. Results for the automated PLSR correction plus MCR-ALS approach compare favorably to an MCR-ALS standalone approach using initial estimates as well as analysis of secondary structure using data processed with a manual baseline correction. The herein described chemometric approach suggests a way to simplify the challenge of handling complex matrices in protein structure analysis by isolating the background from the protein contributions, prior to analysis via other soft-modelling techniques. Consequently, the findings of this study indicate the suitability of online reaction monitoring through mid-IR spectroscopy combined with chemometric techniques as a potential tool in downstream quality control and process automation.

Cardiac Amyloid Quantification Using 124I-Evuzamitide (124I-P5+14) Versus 18F-Florbetapir: A Pilot PET/CT Study.

BACKGROUND: Cardiac amyloid quantification could advance early diagnosis of amyloid cardiomyopathy (CMP) and treatment monitoring. However, current imaging tools are based on indirect measurements. 124I-evuzamitide is a novel pan-amyloid radiotracer binding to amyloid deposits from multiple amyloidogenic proteins. Its ability to quantify cardiac amyloid has not yet been investigated. OBJECTIVES: The objectives of this pilot study were to quantify myocardial 124I-evuzamitide uptake and to compare its diagnostic value to 18F-florbetapir in participants with amyloid CMP and control subjects. METHODS: This study included 46 participants: 12 with light-chain (AL) CMP, 12 with wild-type transthyretin (ATTRwt) CMP, 2 with hereditary amyloidosis, and 20 control subjects. All amyloidosis participants underwent positron emission tomography/computed tomography with 124I-evuzamitide and 18F-florbetapir. Control subjects underwent 124I-evuzamitide (n = 10) or 18F-florbetapir (n = 8) positron emission tomography/computed tomography. Left ventricular percent injected dose (LV% ID) was measured as mean activity concentration × myocardial volume/injected activity. High LV %ID was defined using Youden's index. RESULTS: In CMP participants, median age was 74 years and 92% were men. 124I-evuzamitide LV %ID differed across groups: median AL-CMP 1.48 (IQR: 1.12-1.89), ATTRwt-CMP 2.12 (IQR: 1.66-2.47), and control subjects 0.00 (IQR: 0.00-0.01; overall P < 0.001). High LV %ID perfectly discriminated CMP from control subjects. Discrimination performance was similar for 18F-florbetapir LV %ID. Notably, for ATTRwt-CMP, LV %ID was higher with 124I-evuzamitide than 18F-florbetapir (P = 0.002). 124I-evuzamitide LV %ID was correlated with interventricular septum thickness (Spearman's ρ = 0.78) and LV global longitudinal strain (ρ = 0.54) from echocardiography, and with LV mass index (ρ = 0.82) and extracellular volume (ρ = 0.51) from cardiac magnetic resonance. CONCLUSIONS: 124I-evuzamitide demonstrates uptake by cardiac amyloid and accurately discriminates amyloid CMP from control subjects. In AL-CMP, discrimination performance is similar to 18F-florbetapir. In ATTRwt-CMP, performance may be better with 124I-evuzamitide. Moderate-to-strong correlations of 124I-evuzamitide uptake with cardiac structural and functional metrics suggest valid amyloid quantification. Hence, 124I-evuzamitide is a promising novel radiotracer to detect and quantify cardiac amyloid.

Laser-Based Mid-Infrared Spectroscopy for Monitoring Temperature-Induced Denaturation of Bovine Serum Albumin and De-/Stabilization Effects of Sugars.

Stability of high-concentration protein formulations is considered a major challenge in current biopharmaceutical development. In this work, we introduce laser-based mid-infrared (IR) spectroscopy as a versatile technique to study the effect of protein concentration and presence of sugars on the thermal denaturation of the model protein bovine serum albumin (BSA). Many analytical techniques struggle to characterize the complex structural transition that occurs during protein denaturation. To this end, a commercially available laser-based mid-IR spectrometer equipped with a customized flow cell was employed to record IR spectra of BSA in the temperature range of 25-85 °C. The temperature perturbation induces a conformational change from a native α-helical to an intermolecular ß-sheet secondary structure in BSA. Systematic investigation of the concentration dependence of the α-ß transition temperature between 30 and 90 mg mL-1 shows a trend of decreasing denaturation temperatures at higher BSA concentrations. In-depth chemometric analysis by a multivariate curve resolution-alternating least squares (MCR-ALS) analysis of the spectra, suggested the formation of not one but two intermediates in the denaturation of BSA. Subsequently, the impact of sugars on denaturation temperatures was investigated, revealing both stabilizing (trehalose, sucrose, and mannose) and destabilizing (sucralose) effects, illustrating the applicability of this method as an investigative tool for stabilizers. These results highlight the potential and versatility of laser-based IR spectroscopy for analysis of protein stability at high concentrations and varying conditions.

The Cardiovascular Manifestations of COVID-19.

The Coronavirus 2019 (COVID-19) pandemic, caused by the Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) virus, has resulted in unprecedented morbidity and mortality worldwide. While COVID-19 typically presents as viral pneumonia, cardiovascular manifestations such as acute coronary syndromes, arterial and venous thrombosis, acutely decompensated heart failure (HF), and arrhythmia are frequently observed. Many of these complications are associated with poorer outcomes, including death. Herein we review the relationship between cardiovascular risk factors and outcomes among patients with COVID-19, cardiovascular manifestations of COVID-19, and cardiovascular complications associated with COVID-19 vaccination.

Long-term Cardiovascular Manifestations and Complications of COVID-19: Spectrum and Approach to Diagnosis and Management.

Survivors of coronavirus disease 2019 (COVID-19) may experience persistent symptoms, abnormal diagnostic test findings, incident disease in specific organ systems, or progression of existing disease. Post-acute COVID-19 syndrome (PACS) is defined by persistent, recurrent, or new symptoms, findings, or diagnoses beyond four weeks after the initial infection. PACS has been characterized as a multi-organ syndrome, often with cardiopulmonary symptoms that include fatigue, dyspnea, chest pain, and palpitations. Cardiovascular pathologies in PACS include new-onset arrhythmia, myocarditis, unmasked coronary artery disease, and diastolic dysfunction as well as abnormal findings on electrocardiogram, troponin testing, and cardiac magnetic resonance imaging. In this review, we discuss the cardiovascular symptoms, pathophysiology, clinical investigation, and management strategies for cardiopulmonary symptoms of PACS. We offer a treatment algorithm for primary care clinicians encountering patients with cardiopulmonary PACS and discuss ongoing research on this topic.

The Cardiovascular Manifestations of COVID-19.

The Coronavirus 2019 (COVID-19) pandemic, caused by the Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) virus, has resulted in unprecedented morbidity and mortality worldwide. While COVID-19 typically presents as viral pneumonia, cardiovascular manifestations such as acute coronary syndromes, arterial and venous thrombosis, acutely decompensated heart failure (HF), and arrhythmia are frequently observed. Many of these complications are associated with poorer outcomes, including death. Herein we review the relationship between cardiovascular risk factors and outcomes among patients with COVID-19, cardiovascular manifestations of COVID-19, and cardiovascular complications associated with COVID-19 vaccination.

Barriers to guideline mandated renin-angiotensin inhibitor use: focus on hyperkalaemia.

Hyperkalaemia in patients with chronic disease states can be caused by both abnormalities of potassium homeostasis as well as extrinsic factors such as medication use and potassium intake. In patients with heart failure (HF), chronic kidney disease (CKD), diabetes mellitus (DM), and in those who use renin-angiotensin-aldosterone system inhibitors (RAASi), there is particularly increased risk of chronic or recurrent hyperkalaemia. Hyperkalaemia is often a reason for the suboptimal dosing or complete discontinuation of RAASi. This review presents current options for the management of hyperkalaemia in patients with chronic disease states. It also explores barriers to guideline-mediated RAASi prescribing patterns in these high-risk patients and highlights the unmet need for agents that adequately manage hyperkalaemia in patients with chronic diseases on concomitant RAASi therapy.

New treatments for hyperkalaemia: clinical use in cardiology.

Hyperkalaemia causes significant burden, and even mild hyperkalaemia has been independently associated with increased morbidity and mortality. Patients with chronic disease states, such as heart failure, hypertension, chronic kidney disease and diabetes mellitus, are increasingly susceptible to the development of hyperkalaemia. Options for management of hyperkalaemia had mainly been limited to short-term, temporizing methods with focus on rapid achievement of normokalaemia. Until recently, there was a lack of safe, efficacious and well-tolerated therapies for long-term management. Two novel potassium binders, patiromer and sodium zirconium cyclosilicate, have recently been approved by the US Food and Drug Administration for the management of hyperkalaemia. This review discusses these potassium binders with focus largely on the clinical implications of these agents in patients with chronic cardiovascular conditions.

Effects of post-exposure naps on exposure therapy for social anxiety.

Exposure therapy for social anxiety disorder (SAD) utilizes fear extinction, a memory process enhanced by sleep. We investigated whether naps following exposure sessions might improve symptoms and biomarkers in response to social stress in adults undergoing 5-week exposure-based group SAD therapy. Thirty-two participants aged 18-39 (18 females) with SAD were randomized. Before and after treatment, participants completed the Liebowitz Social Anxiety Scale (LSAS) and underwent a Trier Social Stress Test with psychophysiological monitoring (mpTSST) that included skin conductance (SCL), electromyographic (EMG) and electrocardiographic recording, and an auditory startle procedure while anticipating the social stressor. At sessions 3 and 4, exposure was followed by either a 120-min polysomnographically monitored sleep opportunity (Nap, N = 17) or wakefulness (Wake, N = 15). Primary hypotheses about SAD symptom change (LSAS) and EMG blink-startle response failed to differ with naps, despite significant symptom improvement (LSAS) with therapy. Some secondary biomarkers, however, provided preliminary support for enhanced extinction learning with naps, with trend-level Time (pre-, post-treatment) × Arm interactions and significant reduction from pre- to post treatment in the Nap arm alone for mpTSST SCL and salivary cortisol rise. Because of the small sample size and limited sleep duration, additional well-powered studies with more robust sleep interventions are indicated.

Glucose-Lowering Therapies and Heart Failure in Type 2 Diabetes Mellitus: Mechanistic Links, Clinical Data, and Future Directions.

Diabetes mellitus independently increases the risk of and mortality from heart failure in a manner that is well established but inadequately understood. Glycemic optimization does not eliminate this risk, and measures of glycemic control are insufficient markers of cardiovascular risk. In response to a regulatory guidance from the US Food and Drug Administration, glucose-lowering agents are now routinely evaluated in large cardiovascular outcome trials. These recent trial experiences of novel and established glucose-lowering therapies have shown variable risks and benefits with respect to heart failure. Cardiovascular outcome trials have increasingly included heart failure events as either a component of the primary end point or a secondary adjudicated end point. We comprehensively review each established and novel currently marketed glucose-lowering therapy, their biological targets, mechanisms of action, and relationships with heart failure. We then highlight gaps in available evidence and directions for future research regarding the ascertainment of heart failure-related data in the evaluation of emerging glucose-lowering therapies.

Multiple Avenues of Modulating the Nitric Oxide Pathway in Heart Failure Clinical Trials.

PURPOSE OF REVIEW: This review discusses the integral role of the nitric oxide (NO) pathway in the pathophysiology of heart failure (HF). We emphasize potential therapeutic targets in the NO pathway and review contemporary clinical trials evaluating these novel therapeutic options. RECENT FINDINGS: Nitrates, neprilysin inhibitors, and phosphodiesterase (PDE) inhibitors have all proven to be efficacious in HF patients with systolic dysfunction, with the former two classes of medications producing a net mortality benefit. However, neither PDE inhibitors nor nitrates have demonstrated significant clinical benefit in patients with HF with preserved ejection fraction (HFpEF), and neprilysin inhibitors have yet to be evaluated in this population. Soluble guanylate cyclase (sGC) stimulators have shown significant promise in all HF patients, leading to improvements in both quality of life scores and exercise capacity. Conversely, sGC activators have limited clinical utility in HF, owing largely to safety concerns of hypotension. Inorganic nitrates and nitrites, meanwhile, may be emerging as potential therapies for the HFpEF population. The advent of novel therapies targeting the NO pathway is beginning to create a paradigm shift in the treatment of the HF patient. These therapies offer a promising outlook for the future, with hopes of reducing HF-associated morbidity and mortality.

Exploring heart failure events in contemporary cardiovascular outcomes trials in type 2 diabetes mellitus.

INTRODUCTION: Type 2 diabetes mellitus (DM) and heart failure (HF) are closely related, with the onset of one serving as an independent risk factor for the development or progression of the other. The true impact of their relationship is poorly understood. Since various classes of glucose-lowering therapies have been shown to have differing impact on cardiovascular outcomes, cardiovascular effects of such therapies have been increasingly formally evaluated. Areas covered: With the increasing prevalence of concomitant HF and type 2 DM, HF outcomes serve as important endpoints in trials of glucose-lowering therapies. A thorough literature search of recent cardiovascular outcome trials of glucose-lowering therapies was performed. The authors focus on the availability and extent of ascertainment of data related to HF outcomes in these contemporary clinical trial experiences. Expert commentary: Although early cardiovascular outcome trials did not focus on HF events, these outcomes have been increasingly recognized as meaningful end points in cardiovascular outcome trials. The ascertainment of HF end point data needs to become routine and standardized.

Primary gynecological non-Hodgkin's lymphoma: A differential diagnosis of a pelvic mass.

Primary Non-Hodgkin's lymphoma (NHL) can mimic gynecological malignancy, presenting as a pelvic mass in any organ of the female genital tract. Patients can present with elevated CA-125 and may lack the classical symptoms associated with lymphoma, such as fatigue, fever, night sweats and weight loss. We describe five patients that presented with primary NHL of the genital tract. Patients 1, 2, and 3 were not diagnosed pre-operatively, and underwent unnecessary cytoreductive surgery, while patients 4 and 5 were diagnosed by pre-operative biopsy. The diagnosis of primary pelvic lymphoma should be in the differential diagnosis of gynecological malignancies. Awareness of the disease and pre-operative diagnosis can be beneficial, as the patient may be able to avoid unnecessary staging operations and disease cytoreduction.

Extinction of conditioned fear is better learned and recalled in the morning than in the evening.

Sleep helps emotional memories consolidate and may promote generalization of fear extinction memory. We examined whether extinction learning and memory might differ in the morning and evening due, potentially, to circadian and/or sleep-homeostatic factors. Healthy men (N = 109) in 6 groups completed a 2-session protocol. In Session 1, fear conditioning was followed by extinction learning. Partial reinforcement with mild electric shock produced conditioned skin conductance responses (SCRs) to 2 differently colored lamps (CS+), but not a third color (CS-), within the computer image of a room (conditioning context). One CS+ (CS + E) but not the other (CS + U) was immediately extinguished by un-reinforced presentations in a different room (extinction context). Delay durations of 3 h (within AM or PM), 12 h (morning-to-evening or evening-to-morning) or 24 h (morning-to-morning or evening-to-evening) followed. In Session 2, extinction recall and contextual fear renewal were tested. We observed no significant effects of the delay interval on extinction memory but did observe an effect of time-of-day. Fear extinction was significantly better if learned in the morning (p = .002). Collapsing across CS + type, there was smaller morning differential SCR at both extinction recall (p = .003) and fear renewal (p = .005). Morning extinction recall showed better generalization from the CS + E to CS + U with the response to the CS + U significantly larger than to the CS + E only in the evening (p = .028). Thus, extinction is learned faster and its memory is better generalized in the morning. Cortisol and testosterone showed the expected greater salivary levels in the morning when higher testosterone/cortisol ratio also predicted better extinction learning. Circadian factors may promote morning extinction. Alternatively, evening homeostatic sleep pressure may impede extinction and favor recall of conditioned fear.