The Evolving Role of Cardiovascular Magnetic Resonance Imaging in the Evaluation of Systemic Amyloidosis

Emerging Roles for Dendritic Cells in Heart Failure

The field of cardio-immunology has emerged from discoveries that define roles for innate and adaptive immune responses associated with myocardial inflammation and heart failure. Dendritic cells (DCs) comprise an important cellular compartment that contributes to systemic immune surveillance at the junction of innate and adaptive immunity. Once described as a singular immune subset, we now appreciate that DCs consist of a heterogeneous pool of subpopulations, each with distinct effector functions that can uniquely regulate the acute and chronic inflammatory response. Nevertheless, the cardiovascular-specific context involving DCs in negotiating the biological response to myocardial injury is not well understood. Herein, we review our current understanding of the role of DCs in cardiac inflammation and heart failure, including gaps in knowledge and clinical relevance.

Diagnostic and Prognostic Value of Non-late Gadolinium Enhancement Cardiac Magnetic Resonance Parameters in Cardiac Amyloidosis

Early diagnosis is crucial for the improvement of outcomes of patients with cardiac amyloidosis (CA). Emerging non-late gadolinium enhancement (LGE) based cardiac magnetic resonance (CMR) parameters may facilitate early identification of CA. We sought to investigate the diagnostic and prognostic value of T1, T2 mapping and extracellular volume (ECV) in CA. This single-center prospective analysis included 88 patients with CA, 33 patients with aortic stenosis (AS) and left ventricular hypertrophy (LVH), and 15 healthy controls who completed 3T cardiac MRI at the time of their diagnosis and were assessed with T1, T2 (modified Look-Locker inversion recovery), and ECV mapping of the heart and spleen. Echocardiographic, and biochemical parameters and clinical characteristics and outcomes were collected and analyzed. Of the patients with CA, 71 had light-chain (AL) and 17 had transthyretin (ATTR) amyloidosis. Native T1, native T2 and ECV were significantly higher in patients with CA compared to both patients with LVH-AS (P<0.001) and healthy controls (P<0.001). Good diagnostic accuracy was also demonstrated by measuring the area under the curve (AUC) of the receiver operating characteristic (ROC) curves for native T1 in the region of interest (ROI) (AUC=0.90), native T2 ROI (AUC=0.88), and ECV (AUC=0.90). Furthermore, native T1 ROI, native T2 ROI and ECV, correlated with both NT-proBNP levels and Mayo stage of patients (with AL). Spleen ECV was significantly increased in patients with AL versus ATTR amyloidosis (38.5 vs 30.5; P=0.004) and demonstrated good diagnostic accuracy in differentiating between the two types (AUC=0.79). Native T2 ROI was prognostic of mortality in AL CAwith a HR of 1.97 per 5 ms increase (P=0.001) and remained prognostic after adjustment for age, and Mayo stage. Non-LGE based CMR techniques correlated with established markers of disease and demonstrated good diagnostic accuracy, while native T2 ROI was also prognostic of mortality, thus reinforcing their use in the diagnosis and prognosis of CA.

Quantitative single photon emission computed tomography derived standardized uptake values on 99mTc-PYP scan in patients with suspected ATTR cardiac amyloidosis

Technetium-99 pyrophosphate scintigraphy (99mTc-PYP) provides qualitative and semiquantitative diagnosis of ATTR cardiac amyloidosis (ATTR-CA) using the Perugini scoring system and heart/contralateral heart ratio (H/CL) on planar imaging. Standardized uptake values (SUV) with quantitative single photon emission computed tomography (xSPECT/CT) can offer superior diagnostic accuracy and quantification through precise myocardial contouring that enhances assessment of ATTR-CA burden. We examined the correlation of xSPECT/CT SUVs with Perugini score and H/CL ratio. We also assessed SUV correlation with cardiac magnetic resonance (CMR), echocardiographic, and baseline clinical characteristics. Retrospective review of 78 patients with suspected ATTR-CA that underwent 99mTc-PYP scintigraphy with xSPECT/CT. Patients were grouped off Perugini score (Grade 0-1 and Grade 2-3), H/CL ratio (≥ 1.5 and < 1.5). Two cohorts were also created: myocardium SUVmax > 1.88 and ≤ 1.88 at 1-hour based off an AUC curve with 1.88 showing the greatest sensitivity and specificity. Cardiac SUV retention index was calculated as [SUVmax myocardium/SUVmax vertebrae] × SUVmax paraspinal muscle. Primary outcome was myocardium SUVmax at 1-hour correlation with Perugini grades, H/CL ratio, CMR, and echocardiographic data. Higher Perugini Grades corresponded with higher myocardium SUVmax values, especially when comparing Perugini Grade 3 to Grade 2 and 1 (3.03 ± 2.1 vs 0.59 ± 0.97 and 0.09 ± 0.2, P < 0.001). Additionally, patients with H/CL ≥ 1.5 had significantly higher myocardium SUVmax compared to patients with H/CL ≤ 1.5 (2.92 ± 2.18 vs 0.35 ± 0.60, P < 0.01). Myocardium SUVmax at 1-hour strongly correlated with ECV (r = 0.91, P = 0.001), pre-contrast T1 map values (r = 0.66, P = 0.037), and left ventricle mass index (r = 0.80, P = 0.002) on CMR. SUVs derived from 99mTc-PYP scintigraphy with xSPECT/CT provides a discriminatory and quantitative method to diagnose and assess ATTR-CA burden. These findings strongly correlate with CMR.

Clinical recommendations to diagnose and monitor patients with transthyretin amyloid cardiomyopathy in Asia

Transthyretin amyloid cardiomyopathy (ATTR‐CM) is a debilitating and life‐threatening condition with a heterogeneous clinical presentation. Recent guidelines from the United States and Europe have been published to guide clinical practice and to facilitate management conformity by covering current diagnostic and treatment strategies for patients with ATTR‐CM. These guidelines highlight the importance of an early diagnosis to optimize therapeutic outcomes, specifying the use of tests and imaging techniques to allow accurate, noninvasive diagnosis of ATTR‐CM. However, as regional practice variations across Asia may limit access to healthcare, availability of specific tests, and expertise in assessing diagnostic images, there is an ongoing need to provide an Asian perspective on these clinical guidelines. This review article provides practical recommendations for the diagnosis and monitoring of patients with ATTR‐CM in Asia, highlighting the need for additional guidelines to support a broad and diverse population, consider differing healthcare systems and diagnostic testing availability, and provide a flexible yet robust algorithm.

T2 mapping in myocardial disease: a comprehensive review

Cardiovascular magnetic resonance (CMR) is considered the gold standard imaging modality for myocardial tissue characterization. Elevated transverse relaxation time (T2) is specific for increased myocardial water content, increased free water, and is used as an index of myocardial edema. The strengths of quantitative T2 mapping lie in the accurate characterization of myocardial edema, and the early detection of reversible myocardial disease without the use of contrast agents or ionizing radiation. Quantitative T2 mapping overcomes the limitations of T2-weighted imaging for reliable assessment of diffuse myocardial edema and can be used to diagnose, stage, and monitor myocardial injury. Strong evidence supports the clinical use of T2 mapping in acute myocardial infarction, myocarditis, heart transplant rejection, and dilated cardiomyopathy. Accumulating data support the utility of T2 mapping for the assessment of other cardiomyopathies, rheumatologic conditions with cardiac involvement, and monitoring for cancer therapy-related cardiac injury. Importantly, elevated T2 relaxation time may be the first sign of myocardial injury in many diseases and oftentimes precedes symptoms, changes in ejection fraction, and irreversible myocardial remodeling. This comprehensive review discusses the technical considerations and clinical roles of myocardial T2 mapping with an emphasis on expanding the impact of this unique, noninvasive tissue parameter.

99m Technetium-pyrophosphate scintigraphy: a practical guide for early diagnosis of transthyretin amyloid cardiomyopathy

Transthyretin amyloid cardiomyopathy (ATTR‐CM) is caused by the cardiac deposition of insoluble amyloid fibrils formed by misfolded transthyretin proteins and is associated with various cardiac symptoms, such as progressive heart failure, conduction disturbance, and arrhythmia. The implementation of ^99mtechnetium (^99mTc)‐labelled bone radiotracer scintigraphy for diagnosing ATTR‐CM has enabled accurate diagnosis of the disease with high sensitivity and specificity and positioned this diagnostic modality as an integral part of disease diagnostic algorithms. In 2020, ^99mTc‐pyrophosphate scintigraphy received exceptional approval for Japanese national health insurance reimbursement as a diagnostic method of ATTR‐CM. Nevertheless, the utility of ^99mTc‐labelled bone radiotracer scintigraphy and the importance of an early diagnosis of suspected ATTR‐CM using this technique have yet to be internalized as common practice by general cardiologists, and guidance on daily clinical scenarios to consider this technique for a diagnosis of suspected ATTR‐CM is warranted. In this review, we discuss the utility of ^99mTc‐labelled bone radiotracer scintigraphy for the early diagnosis of ATTR‐CM based on published literature and the outcomes of an advisory board meeting. This review also discusses clinical scenarios that could support early diagnosis of suspected ATTR‐CM as well as common pitfalls, correct implementation, and future perspectives of ^99mTc‐labelled bone radiotracer scintigraphy in daily clinical practice. The clinical scenarios to consider ^99mTc‐labelled bone radiotracer scintigraphy in daily practice may include, but are not limited to, patients with a family history of the hereditary type of disease; elderly patients (aged ≥60 years) with unexplained cardiac findings (e.g. cardiac hypertrophy associated with abnormalities on an electrocardiogram, heart failure with preserved ejection fraction associated with unexplained left ventricular hypertrophy, and heart failure with reduced ejection fraction associated with atrial fibrillation and left ventricular hypertrophy); and patients with cardiac hypertrophy associated with diastolic dysfunction, right ventricular/interatrial septum/valve thickness, left ventricular sparkling, or apical sparing. Cardiac hypertrophy and persistent elevation in cardiac troponin in elderly patients are also suggestive of ATTR‐CM. ^99mTc‐labelled bone radiotracer scintigraphy is also recommended in patients with characteristic cardiac magnetic resonance findings (e.g. diffuse subendocardial late gadolinium enhancement patterns, native T1 increase, and increase in extracellular volume) or patients with cardiac hypertrophy and bilateral carpal tunnel syndrome.

Advanced cardiac imaging in athlete's heart: unravelling the grey zone between physiologic adaptation and pathology

Over the last decades, interest toward athlete’s heart has progressively increased, leading to improve the knowledge on exercise-induced heart modifications. Sport may act as a trigger for life-threatening arrhythmias in patients with structural or electrical abnormalities, hence requiring to improve the diagnostic capability to differentiate physiological from pathological remodeling. Pathological alterations are often subtle at the initial stages; therefore, the challenge is to promptly identify athletes at risk of sudden cardiac death during the pre-participation screening protocols. Advanced imaging modalities such as coronary computed tomography angiography (CCTA) and cardiac magnetic resonance (CMR) can non-invasively depict coronary vessels and provide a deep morpho-functional and structural characterization of the myocardium, in order to rule out pathological life threatening alterations, which may overlap with athletes’ heart remodeling. The purpose of the present narrative review is to provide an overview of most frequent diagnostic challenges, defining the boundaries between athlete's heart remodeling and pathological structural alteration with a focus on the role and importance of CCTA and CMR.

Imaging Techniques as an Aid in the Early Detection of Cardiac Amyloidosis

The idea that performing a proper succession of imaging tests and techniques allows an accurate and early diagnosis of cardiac amyloidosis, avoiding the need to perform the myocardial biopsy, is becoming increasingly popular. Furthermore, being imaging techniques non-invasive, it is possible to perform the follow-up of the pathology through repeated image acquisitions. In the present review, the various innovative imaging methodologies are presented, and it is discussed how they have been applied for early diagnosis of cardiac amyloidosis (CA), also to distinguish the two most frequent subtypes in CA: immunoglobulin light chain amyloidosis (AL) and transthyretin amyloidosis (ATTR); this allows to perform the therapy in a targeted and rapid manner.

Diagnosis of wild-type transthyretin amyloid cardiomyopathy in Japan: red-flag symptom clusters and diagnostic algorithm

Wild‐type transthyretin amyloid cardiomyopathy (ATTRwt‐CM) is caused by the deposition of wild‐type transthyretin (TTR) amyloid fibrils in the heart. The age at diagnosis of ATTRwt‐CM is reported to be approximately 70–80 years, and patients commonly present with non‐disease‐specific cardiac abnormalities, such as heart failure with preserved ejection fraction and diastolic dysfunction. The disease can be fatal if left untreated, with an approximate survival of 3–5 years from diagnosis. An oral TTR stabilizer, tafamidis, has enabled early intervention for the treatment of ATTRwt‐CM. However, awareness of ATTRwt‐CM remains low, and misdiagnosis and a delay in diagnosis are common. This review discusses the epidemiology, characteristics, treatment strategy, and red‐flag symptoms and signs of ATTRwt‐CM based on the published literature, as well as recent advances in diagnostic modalities that enable early and accurate diagnosis of the disease. We also discuss an algorithm for early and accurate diagnosis of ATTRwt‐CM in daily clinical practice. In our diagnostic algorithm, a suspected diagnosis of ATTRwt‐CM should be triggered by unexplained left ventricular hypertrophy (LVH), which is LVH that cannot be explained by an increased afterload due to hypertension or valvular disease. In addition, heart failure symptoms, laboratory test results (N‐terminal pro‐B‐type natriuretic peptide, high‐sensitivity troponin T, or high‐sensitivity troponin I), electrocardiogram and imaging (echocardiogram or cardiac magnetic resonance) data, age (≥60 years), and medical history suggestive of ATTRwt‐CM (e.g. carpal tunnel syndrome) should be examined. Detailed examinations using bone scintigraphy and monoclonal protein detection tests followed by tissue biopsy, amyloid typing, and TTR genetic testing are warranted for a definite diagnosis of ATTRwt‐CM.

Native T1 mapping and extracellular volume fraction for differentiation of myocardial diseases from normal CMR controls in routine clinical practice

Background

This study aimed to determine native T1 and extracellular volume fraction (ECV) in distinct types of myocardial disease, including amyloidosis, dilated cardiomyopathy (DCM), hypertrophic cardiomyopathy (HCM), myocarditis and coronary artery disease (CAD), compared to controls.

Methods

We retrospectively enrolled patients with distinct types of myocardial disease, CAD patients, and control group (no known heart disease and negative CMR study) who underwent 3.0 Tesla CMR with routine T1 mapping. The region of interest (ROI) was drawn in the myocardium of the mid left ventricular (LV) short axis slice and at the interventricular septum of mid LV slice. ECV was calculated by actual hematocrit (Hct) and synthetic Hct. T1 mapping and ECV was compared between myocardial disease and controls, and between CAD and controls. Diagnostic yield and cut-off values were assessed.

Results

A total of 1188 patients were enrolled. The average T1 values in the control group were 1304 ± 42 ms at septum, and 1294 ± 37 ms at mid LV slice. The average T1 values in patients with myocardial disease and CAD were significantly higher than in controls (1441 ± 72, 1349 ± 59, 1345 ± 59, 1355 ± 56, and 1328 ± 54 ms for septum of amyloidosis, DCM, HCM, myocarditis, and CAD). Native T1 of the mid LV level and ECV at septum and mid LV with actual and synthetic Hct of patients with myocardial disease or CAD were significantly higher than in controls.

Conclusions

Although native T1 and ECV of patients with cardiomyopathy and CAD were significantly higher than controls, the values overlapped. The greatest clinical utilization was found for the amyloidosis group.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12872-021-02086-3.

Utility of Cardiac Magnetic Resonance Imaging in the Diagnosis, Prognosis, and Treatment of Infiltrative Cardiomyopathies

PURPOSE OF REVIEW

Diagnosis of infiltrative cardiomyopathies can be challenging despite differences in clinical manifestations due to overlapping cardiac manifestations. We review the salient findings by cardiac magnetic resonance imaging that aids in diagnosis, as well the potential implications for prognosis and treatment.

RECENT FINDINGS

Cardiac magnetic resonance imaging has added substantially to our understanding of various infiltrative cardiomyopathies, and the addition of late gadolinium enhancement imaging and parametric mapping has yielded additional insights regarding potential diagnoses, prognosis, and therapy. Cardiac magnetic resonance imaging should be employed in the setting of suspected hypertrophic or infiltrative cardiomyopathies to aid in diagnosis. In the setting of cardiac amyloidosis and Fabry disease, there is data to suggest that cardiac magnetic resonance imaging is useful for risk stratification as well as for monitoring response to therapy.

Regional Amyloid Burden Differences Evaluated Using Quantitative Cardiac MRI in Patients with Cardiac Amyloidosis

Objective

This study aimed to investigate the regional amyloid burden and myocardial deformation using T1 mapping and strain values in patients with cardiac amyloidosis (CA) according to late gadolinium enhancement (LGE) patterns.

Materials and Methods

Forty patients with CA were divided into 2 groups per LGE pattern, and 15 healthy subjects were enrolled. Global and regional native T1 and T2 mapping, extracellular volume (ECV), and cardiac magnetic resonance (CMR)-feature tracking strain values were compared in an intergroup and interregional manner.

Results

Of the patients with CA, 32 had diffuse global LGE (group 2), and 8 had focal patchy or no LGE (group 1). Global native T1, T2, and ECV were significantly higher in groups 1 and 2 than in the control group (native T1: 1384.4 ms vs. 1466.8 ms vs. 1230.5 ms; T2: 53.8 ms vs. 54.2 ms vs. 48.9 ms; and ECV: 36.9% vs. 51.4% vs. 26.0%, respectively; all, p < 0.001). Basal ECV (53.7%) was significantly higher than the mid and apical ECVs (50.1% and 50.0%, respectively; p < 0.001) in group 2. Basal and mid peak radial strains (PRSs) and peak circumferential strains (PCSs) were significantly lower than the apical PRS and PCS, respectively (PRS, 15.6% vs. 16.7% vs. 26.9%; and PCS, −9.7% vs. −10.9% vs. −15.0%; all, p < 0.001). Basal ECV and basal strain (2-dimensional PRS) in group 2 showed a significant negative correlation (r = −0.623, p < 0.001). Group 1 showed no regional ECV differences (basal, 37.0%; mid, 35.9%; and apical, 38.3%; p = 0.184).

Conclusion

Quantitative T1 mapping parameters such as native T1 and ECV may help diagnose early CA. ECV, in particular, can reflect regional differences in the amyloid deposition in patients with advanced CA, and increased basal ECV is related to decreased basal strain. Therefore, quantitative CMR parameters may help diagnose CA and determine its severity in patients with or without LGE.

The Role of Multi-modality Imaging in the Diagnosis of Cardiac Amyloidosis: A Focused Update

Cardiac amyloidosis (CA) is a unique disease entity involving an infiltrative process, typically resulting in a restrictive cardiomyopathy with diastolic heart failure that ultimately progresses to systolic heart failure. The two most common subtypes are light-chain and transthyretin amyloidosis. Early diagnosis of this disease entity, especially light-chain CA subtype, is crucial, as it portends a poorer prognosis. This review focuses on the clinical utility of the various imaging modalities in the diagnosis and differentiation of CA subtypes. This review also aims to highlight the key advances in each of the imaging modalities in the diagnosis and prognostication of CA.

Ventricular Arrhythmias in Cardiac Amyloidosis: A Review of Current Literature

Cardiac Amyloidosis is an infiltrative cardiomyopathy which occurs secondary to deposition of mis-folded protein in the myocardium, with the two most common subtypes being AL amyloidosis and TTR amyloidosis. The pathogenesis of the disease is multifaceted and involves a variety of mechanisms including an inflammatory response cascade, oxidative stress and subsequent separation of myocyte fibrils. Cardiac Amyloidosis frequently results in congestive cardiac failure and arrhythmias, from a disruption in cardiac substrate with subsequent electro-mechanical remodelling. Disease progression is usually demonstrated by development of progressive pump failure, which may be seen with a high arrhythmic burden, usually portending a poor prognosis. There is a paucity of literature on the clinical implications of ventricular arrhythmias in the context of cardiac amyloidosis. The important diagnostic investigations for these patients include transthoracic echocardiography, cardiac magnetic resonance imaging and an electrophysiology study. Whilst there are no robust management guidelines, studies have indicated benefits from contemporary pharmacological therapy and case-by-case catheter ablation. There are novel directed therapies available for TTR amyloidosis that have shown to improve overall survival. The role of ICD therapy in cardiac amyloidosis is controversial, with benefits seen predominantly in early phases of the disease process. The only definitive surgical therapy includes heart transplantation, but is largely indicated for progressive decompensated heart failure (Figure 1). Further large-scale studies are required to better outline management paradigms for treating ventricular arrhythmias in cardiac amyloidosis.

Amyloidosis in Heart Failure

PURPOSE

Amyloidosis represents an increasingly recognized but still frequently missed cause of heart failure. In the light of many effective therapies for light chain (AL) amyloidosis and promising new treatment options for transthyretin (ATTR) amyloidosis, awareness among caregivers needs to be raised to screen for amyloidosis as an important and potentially treatable differential diagnosis. This review outlines the diversity of cardiac amyloidosis, its relation to heart failure, the diagnostic algorithm, and therapeutic considerations that should be applied depending on the underlying type of amyloidosis.

RECENT FINDINGS

Non-biopsy diagnosis is feasible in ATTR amyloidosis in the absence of a monoclonal component resulting in higher detection rates of cardiac ATTR amyloidosis. Biomarker-guided staging systems have been updated to facilitate risk stratification according to currently available biomarkers independent of regional differences, but have not yet prospectively been tested. Novel therapies for hereditary and wild-type ATTR amyloidosis are increasingly available. The complex treatment options for AL amyloidosis are improving continuously, resulting in better survival and quality of life. Mortality in advanced cardiac amyloidosis remains high, underlining the importance of early diagnosis and treatment initiation. Cardiac amyloidosis is characterized by etiologic and clinical heterogeneity resulting in a frequently delayed diagnosis and an inappropriately high mortality risk. New treatment options for this hitherto partially untreatable condition have become and will become available, but raise challenges regarding their implementation. Referral to specialized centers providing access to extensive and targeted diagnostic investigations and treatment initiation may help to face these challenges.

Sudden death in lambda light chain AL cardiac amyloidosis: a review of literature and update for clinicians and pathologists

Light chain (AL) amyloidosis is the most common type of systemic amyloidosis, affecting around 10 people per million per year. In Europe, approximately 5000 new diagnosis per year are reported. Deposition of amyloid fibrils derived from antibody light chains are key pathogenic agents in AL amyloidosis. They can be deposited in multiple organs but cardiac involvement carries a major risk of mortality. The prognosis is poor in cases associated with multiple myeloma. The average survival is around 1 year. Up to half of all patients with cardiac amyloidosis die suddenly; 75% ofthose deaths are due to heart failure. Ventricular arrhythmia is also associated with cardiac amyloidosis and unexpected death. It is crucial to make a diagnosis and start treatment at an early stage. Recent data suggest that cardiac amyloidosis has become a treatable and curable condition with a combination of agents targeting multiple steps of the amyloid cascade. ICD implantation may not be as effective for the therapy of light chain (AL) cardiac amyloidosis as supposed earlier. In cases of unexpected and sudden death, autopsy may show unknown conditions and is valuable to assess existing risks for family members. Even after careful autopsy, a proportion of sudden deaths, ranging from 2 to 54%, remain unexplained and this broad range of values is likely due to the heterogeneity of autopsy protocols. Post mortem diagnosis of cardiac amyloidosis still represents a challenge for forensic pathologists. Detailed morphologic study of the heart and a complete histopathologic study are mandatory. Immunohistochemistry is essential for amyloid subclassification. A review of existing literature is performed by the authors and a methodological approach in post mortem diagnosis of light chain AL cardiac amyloidosis is proposed. Both macroscopic and microscopic findings are discussed.