Myocardial Amyloid Quantification with Look-Locker Magnetic Resonance Sequence in Cardiac Amyloidosis. Diagnostic Accuracy in Clinical Practice and Histological Validation

State of the Art: Quantitative Cardiac MRI in Cardiac Amyloidosis

Cardiac amyloidosis (CA) is characterized by amyloid infiltration in the myocardial extracellular space, causing heart failure. Patients with CA are currently underdiagnosed. Cardiac involvement is significantly associated with the prognosis and treatment decision-making for CA. Early identification and accurate stratification are the crucial first step in patient management. Comprehensive cardiac MRI-based evaluation of the cardiac structure, function, and myocardial tissue characterization assesses cardiac involvement by tracing disease processes. Emerging quantitative tissue characterization techniques have introduced new measures that can identify early staged CA and monitor disease progression or response after treatment. Quantitative cardiac MRI is becoming an instrumental tool in understanding CA, which leads to changes in individualized patient care. This review aimed to discuss the quantitative cardiac MRI-based assessment of CA using established and emerging techniques. EVIDENCE LEVEL: 5 TECHNICAL EFFICACY: Stage 3.

Prevalence and Clinical Outcomes of Transthyretin Amyloidosis: A Systematic Review and Meta-analysis

BACKGROUND

Systematic evidence on the prevalence and clinical outcome of transthyretin amyloidosis (ATTR) is missing. We explored: a) the prevalence of cardiac amyloidosis in various patient subgroups, b) survival estimates for ATTR subtypes and c) the effects of novel therapeutics on the natural course of disease.

METHODS

A systematic review of literature published in Medline before 31/12/2021 was performed for the prevalence of cardiac amyloidosis & all-cause mortality of ATTR patients. Extracted data included sample size, age, sex, and all-cause mortality at 1, 2 and 5-years. Subgroup analyses were performed for ATTR subtype i.e., wild type ATTR (wtATTR) vs. hereditary ATTR (htATTR), htATTR genotypes and treatment subgroups.

RESULTS

We identified a total of 62 studies (n=277,882 individuals) reporting the prevalence of cardiac amyloidosis, which was high among patients with a hypertrophic cardiomyopathy phenotype, HFpEF, and elderly with aortic stenosis. Data on ATTR mortality were extracted from 95 studies (n=18,238 ATTR patients). Patients with wtATTR were older (p=7x10^-10 ) and more frequently male (p=5x10^-20 ) vs. htATTR. The 2-year survival of ATTR was 73.3% (95%CI 71.6-76.2); for non-subtyped ATTR 70.4% (95%CI 66.9-73.9), for wtATTR (76.0%, 95%CI: 73.0-78.9) and for htATTR (77.2%, 95%CI: 74.0-80.4); in meta-regression analysis wtATTR was associated with higher survival after adjusting for confounders. There was an interaction between survival and htATTR genotypes (p=10^-15 , Val30Met having the lowest and Val122Ile/Thr60Ala the highest mortality). ATTR 2-year survival was higher on tafamidis/patisiran compared to natural disease course (79.9%, 95%CI: 74.4-85.3 vs. 72.4%, 95%CI 69.8-74.9, p<0.05).

CONCLUSIONS

We report the prevalence of ATTR in various population subgroups and provide survival estimates for the natural course of disease and the effects of novel therapeutics. Important gaps in worldwide epidemiology research in ATTR were identified. This article is protected by copyright. All rights reserved.

Advances in the diagnosis and treatment of transthyretin amyloidosis with cardiac involvement

Amyloidosis is caused by extracellular deposition of insoluble abnormal fibrils constituted by misfolded proteins, which can modify tissue anatomy and hinder the function of multiple organs including the heart. Amyloidosis that can affect the heart includes mostly systemic amyloidosis (amyloid light chain, AL) and transthyretin amyloidosis (ATTR). The latter can be acquired in elderly patients (ATTRwt), or be inherited in younger individuals (ATTRm). The diagnosis is demanding given the high phenotypic heterogeneity of the disease. Therefore, "red flags," which are suggestive features giving support to diagnostic suspicion, are extremely valuable. However, the lack of broad awareness among clinicians represents a major obstacle for early diagnosis and treatment of ATTR. Furthermore, recent implementation of noninvasive diagnostic techniques has revisited the need for endomyocardial biopsy (EMB). In fact, unlike AL amyloidosis, which requires tissue confirmation and typing for diagnosis, ATTR can now be diagnosed noninvasively with the combination of bone scintigraphy and the absence of a monoclonal protein. Securing the correct diagnosis is pivotal for the newly available therapeutic options targeting both ATTRm and ATTRwt, and are directed to either stabilization of the abnormal protein or the reduction of the production of transthyretin. The purpose of this article is to review the contemporary aspects of diagnosis and management of transthyretin amyloidosis with cardiac involvement, summarizing also the recent therapeutic advances with tafamidis, patisiran, and inotersen.

Cardiac amyloidosis: An underdiagnosed/underappreciated disease

Cardiac amyloidosis or amyloid cardiomyopathy (ACM), commonly resulting from extracellular deposition of amyloid fibrils consisted of misfolded immunoglobulin light chain (AL) or transthyretin (TTR) protein, is an underestimated cause of heart failure and cardiac arrhythmias. Among the three types of cardiac amyloidosis (wild-type or familial TTR and light-chain), the wild-type (Wt) TTR-related amyloidosis (ATTR) is an increasingly recognized cause of heart failure with preserved ejection fraction (HFpEF), and amyloidosis should be considered in the differential diagnosis of this heart failure group of patients. Recent advances in the diagnosis and drug treatment of ACM have ushered in a new era in early disease detection and better management of these patients. Certain clues in cardiac and extracardiac manifestations of ACM may heighten clinical suspicion and guide further confirmatory testing. Newer noninvasive imaging methods (strain echocardiography, cardiac magnetic resonance and bone scintigraphy) may obviate the need for endomyocardial biopsy in ATTR patients, while newer targeted therapies may alter the adverse prognosis in these patients. Early recognition of ACM is crucial in halting the disease process before irreversible organ damage occurs. Chemotherapy and stem-cell transplantation combined with immunomodulatory therapy may also favorably affect the course and prognosis of light chain ACM. Finally, in select patients with end-stage disease, heart transplantation may render results comparable to non-ACM patients. All these issues are herein reviewed.

Regional amyloid distribution and impact on mortality in light-chain amyloidosis: a T1 mapping cardiac magnetic resonance study

BACKGROUND

T1 mapping allows quantitative assessment of "diffuse" deposition of amyloid protein in the myocardium. Early detection of cardiac involvement and potential prognostic improvement could benefit patients with AL amyloidosis.

OBJECTIVES

This study aims to evaluate the regional variation of amyloid infiltration in the left ventricle and the prognostic value of T1 mapping in patients with AL amyloidosis.

METHODS

We prospectively enrolled 77 patients with AL amyloidosis who underwent cardiac magnetic resonance on a 3.0-T scanner. Native T1 and extracellular volume (ECV) were quantitated on the basal, mid, and apical levels of the left ventricle. Late gadolinium enhancement (LGE) pattern (no or non-specific LGE, sub-endocardial LGE, and transmural LGE) was also assessed. Forty healthy subjects served as controls. The primary end point was all-cause mortality.

RESULTS

Basal ECV (26.9 ± 2.8% versus 31.1 ± 4.9%, p < .001) were lower than apical ECV in the healthy controls; however, basal ECV (60.6 ± 11.5% versus 53.0 ± 9.6%, p = .003) were significantly higher than apical ECV in patients with transmural LGE. During the follow-up period (median duration, 28 months; 25th-75th percentile, 13.5-38.0 months), 46 patients died. Basal ECV has the largest area under the curve of 0.845 (95% CI, 0.747-0.917) to predict all-cause mortality. Multivariable Cox analysis indicated that basal ECV was an independent prognostic factor and showed incremental prognostic value beyond NYHA class, Mayo stage, and LGE pattern.

CONCLUSION

We demonstrated that T1 mapping may have the potential to detect a characteristic amyloid deposition with a decreasing gradient from base to apex. Furthermore, myocardial ECV indicated that basal amyloid infiltration provided robust and incremental prognostic value in patients with AL amyloidosis.

Diagnosis of cardiac amyloidosis: a systematic review on the role of imaging and biomarkers

BACKGROUND

Cardiac Amyloidosis (CA) pertains to the cardiac involvement of a group of diseases, in which misfolded proteins deposit in tissues and cause progressive organ damage. The vast majority of CA cases are caused by light chain amyloidosis (AL) and transthyretin amyloidosis (ATTR). The increased awareness of these diseases has led to an increment of newly diagnosed cases each year.

METHODS

We performed multiple searches on MEDLINE, EMBASE and the Cochrane Database of Systematic Reviews. Several search terms were used, such as "cardiac amyloidosis", "diagnostic modalities cardiac amyloidosis" and "staging cardiac amyloidosis". Emphasis was given on original articles describing novel diagnostic and staging approaches to the disease.

RESULTS

Imaging techniques are indispensable to diagnosing CA. Novel ultrasonographic techniques boast high sensitivity and specificity for the disease. Nuclear imaging has repeatedly proved its worth in the diagnostic procedure, with efforts now focusing on standardization and quantification of amyloid load. Because the latter would be invaluable for any staging system, those spearheading research in magnetic resonance imaging of the disease are also trying to come up with accurate tools to quantify amyloid burden. Staging tools are currently being developed and validated for ATTR CA, in the spirit of the acclaimed Mayo Staging System for AL.

CONCLUSION

Cardiac involvement confers significant morbidity and mortality in all types of amyloidosis. Great effort is made to reduce the time to diagnosis, as treatment in the initial stages of the disease is tied to better prognosis. The results of these efforts are highly sensitive and specific diagnostic modalities that are also reasonably cost effective.

The Role of Cardiovascular Magnetic Resonance for Surveillance of Cardiac Performance upon Receipt of Potentially Cardiotoxic Cancer Therapeutics

PURPOSE OF REVIEW

Advancements in cancer treatment have resulted in improved cancer-related survival and consequently an increase in the number of cancer survivors. Unfortunately, associated with this increase in cancer-related survivorship, cardiac events have occurred with increasing frequency in cancer survivors. Recognition that cancer survivors are at increased risk for cardiovascular (CV) morbidity has generated interest to develop cardiac imaging techniques that identify subclinical CV disease during receipt of potentially cardiotoxic cancer treatment. Since subclinical cardiovascular disease precedes future cardiac events, early recognition of subclinical CV disease during receipt of potentially cardiotoxic cancer treatment offers the opportunity to initiate strategies that prevent further evolution of subclinical CV disease as well as cardiac events.

RECENT FINDINGS

Cardiovascular magnetic resonance imaging (CMR) is an advanced imaging technique that identifies imaging markers of subclinical cardiovascular disease in patients receiving potentially cardiotoxic cancer treatment regimens. In this article, we review the use of CMR for identifying subclinical cardiac disease in patients receiving potentially cardiotoxic cancer treatment regimens. The ability of contemporary CMR to accurately define cardiac anatomy, function, and tissue characteristics may represent a critical tool to assess patients with cancer.

The Role of Cardiovascular Magnetic Resonance in the Management of Patients with Cancer

PURPOSE OF REVIEW

This article reviews the utility of cardiovascular magnetic resonance imaging (CMR) to detect abnormalities of the cardiovascular system that may result from cancer or its treatment.

RECENT FINDINGS

With CMR, one may assess cardiac anatomy, function, myocardial perfusion, tissue composition, and blood flow. For those with cancer, these capabilities allow one to differentiate myocardial masses that may relate to the presence of cancer and evaluate diseases of the pericardium. These features facilitate measurement of left ventricular (LV) volumes, ejection fraction, mass, strain, T1 and T2 relaxation properties, and the extracellular volume fraction all of which may be useful for detecting subclinical cardiovascular injury that results from the receipt of potentially cardiotoxic cancer treatment. CMR can provide an effective and efficient means to identify clinical abnormalities resulting from the diagnosis of cancer or subclinical cardiac injury that may be related to receipt of the therapy for cancer.