Cardiac amyloid deposition and the forensic autopsy - A review and analysis

Although amyloid material in the heart is not infrequently encountered at autopsy it may on occasion be difficult to determine the significance in terms of possible contributions to the terminal mechanisms of death. A review was undertaken of the literature and of autopsy cases at Forensic Science SA over a 20-year-period (2003-2022) for all cases where significant amyloid material had been encountered on microscopy of the heart. Sixteen cases were found consisting of 11 cases where cardiac amyloid was involved in the lethal episode, and five where it was considered an incidental feature. Of the 11 lethal cases, there were three where cardiac amyloidosis was the cause of death, and eight where it was a contributing factor, along with ischaemic heart disease (N = 7) and bronchopneumonia (N = 1). The age range was 47-92 years, average 78.6 years, with a male to female ratio of 10:1. The weights of the hearts ranged from 496 to 1059 g - average 648 g. Of the five cases where it was considered an incidental finding, the causes of death were blunt head trauma (N = 2), small intestinal ischaemia (N = 2) and small intestinal obstruction (N = 1). The weights of the hearts ranged from 299 to 487 g, average 369 g. The most relevant types of amyloidosis in forensic cases tend to be light chain amyloidosis, senile cardiac amyloidosis and familial amyloid cardiomyopathy. Other forms of amyloidosis that affect the heart, which include reactive amyloidosis, haemodialysis-related amyloidosis and isolated atrial amyloidosis, either have minimal or no clinical significance, or are of uncertain significance. While it may be difficult to determine the prognostic significance of amyloid material at autopsy clinicopathological correlation may provide useful supportive information.

Exploring Transthyretin Amyloid Cardiomyopathy: A Comprehensive Review of the Disease and Upcoming Treatments

Transthyretin amyloid cardiomyopathy (ATTR-CM) is a mutation-based genetic disorder due to the accumulation of unstable transthyretin protein and presents with symptoms of congestive heart failure (CHF) and numerous extracardiac symptoms like carpal tunnel syndrome and neuropathy. Two subtypes of ATTR-CM are hereditary and wild-type, both of which have different risk factors, gender prevalence and major clinical symptoms. Timely usage of imaging modalities like echocardiography, cardiac magnetic imaging resonance, and cardiac scintigraphy has made it possible to suspect ATTR-CM in patients presenting with CHF. Management of ATTR-CM includes appropriate treatment for heart failure for symptomatic relief, prevention of arrhythmias and heart transplantation for nonresponders. With the recent approval of tafamidis in the successful management of ATTR-CM, numerous potential therapeutic points have been identified to stop or delay the progression of ATTR-CM. This article aims to provide a comprehensive review of ATTR-CM and insights into its novel therapeutics and upcoming treatments.

Cardiac Amyloidosis Presenting as Isolated Severe Pulmonary Artery Hypertension

A 58-year-old woman presented with dyspnea on exertion and bilateral pedal edema for 3 months. She was found to have severe pulmonary hypertension (PH) with the right ventricular failure. The detailed evaluation did not reveal any secondary cause for PH (cardiac disease, pulmonary embolism, interstitial or other lung disease, collagen vascular disease, portal hypertension, or chronic liver disease). Meanwhile, her workup revealed multiple myeloma. Abdominal fat pad biopsy was performed because PH as an isolated manifestation of cardiac amyloidosis was previously reported. Thus, she was diagnosed to have systemic amyloidosis secondary to myeloma. PH was attributed to cardiac amyloidosis. We present a patient with PH and amyloidosis secondary to multiple myeloma. PH and primary systemic amyloidosis without cardiac or parenchymal lung involvement are extremely rare with only a few cases reported in the past.

Diagnosing Cardiac Amyloidosis: From Heart Failure to Electrical Storm

Cardiac amyloidosis is a condition when amyloid fibers are deposited in the extracellular space of the heart causing tachyarrhythmias, heart failure, or sudden cardiac death. We present a 71-year-old woman presenting with dyspnea on admission. Echocardiogram revealed diastolic heart failure and left ventricular hypertrophy with strain pattern concerning for an infiltrative process. She was discharged with diuretic therapy and scheduled for a cardiac magnetic resonance imaging. One week after discharge, she was readmitted with progressive shortness of breath and syncope. She was found to be in shock and had multiple episodes of cardiac arrest with both ventricular tachycardia and pulseless electrical activity. She developed electrical storm and eventually passed within 24 hours. Autopsy revealed gross cardiomegaly and left ventricular hypertrophy with Congo red staining revealing amyloid fibrils with apple-green birefringence. This case demonstrates the rapid progression of cardiac amyloidosis from acute-onset diastolic heart failure to uncontrollable ventricular tachycardia, and eventually death. We review the literature regarding multiple diagnostic modalities that facilitate the confirmation of cardiac amyloidosis.

Cardiac scintigraphy with 99mTc-diphosphonates in cardiac amyloidosis

Transthyretin cardiac amyloidosis (ATTR) has traditionally been considered a rare, difficult-to-diagnose and untreatable disease. However, its prevalence is known to be greater than what was previously thought, non-invasive diagnostic methods are available, and that effective treatments are emerging. In this context, cardiac scintigraphy (CS) with ^99mTc-labelled diphosphonates has aroused a noticeable surge in interest by demonstrating high sensitivity and specificity for the reliable, non-invasive diagnosis of ATTR. By way of a guide, this article aims to identify the critical components in the performance of CS that are useful in everyday clinical practice and, thus, help specialists use optimal radiopharmaceuticals, obtain the most appropriate images, interpret the results thereof, and acquaint themselves with those clinical scenarios in which it is convenient to perform CS.

Crystal structure of 6aJL2-R24G light chain variable domain: Does crystal packing explain amyloid fibril formation?

Light chain amyloidosis is one of the most common systemic amyloidosis, characterized by the deposition of immunoglobulin light variable domain as insoluble amyloid fibrils in vital organs, leading to the death of patients. Germline λ6a is closely related with this disease and has been reported that 25% of proteins encoded by this germline have a change at position 24 where an Arg is replaced by a Gly (R24G). This germline variant reduces protein stability and increases the propensity to form amyloid fibrils. In this work, the crystal structure of 6aJL2-R24G has been determined to 2.0 Å resolution by molecular replacement. Crystal belongs to space group I2₁2₁2₁ (PDB ID 5JPJ) and there are two molecules in the asymmetric unit. This 6aJL2-R24G structure as several related in PDB (PDB entries: 5C9K, 2W0K, 5IR3 and 1PW3) presents by crystal packing the formation of an octameric assembly in a helicoidal arrangement, which has been proposed as an important early stage in amyloid fibril aggregation. However, other structures of other protein variants in PDB (PDB entries: 3B5G, 3BDX, 2W0L, 1CD0 and 2CD0) do not make the octameric assembly, regardless their capacity to form fibers in vitro or in vivo. The analysis presented here shows that the ability to form the octameric assembly in a helicoidal arrangement in crystallized light chain immunoglobulin proteins is not required for amyloid fibril formation in vitro. In addition, the fundamental role of partially folded states in the amyloid fibril formation in vitro, is not described in any crystallographic structure published or analyzed here, being those structures, in any case examples of proteins in their native states. Those partially folded states have been recently described by cryo-EM studies, showing the necessity of structural changes in the variants before the amyloid fiber formation process starts.

Cerebral embolism secondary to cardiac amyloidosis: A case report and literature review

Cardiac amyloidosis (CA) describes a group of heterogeneous diseases that are characterized by the extracellular fibril deposition of amyloid protein in the myocardium. The abnormal protein is usually derived from light-chain amyloidosis, mutant transthyretin amyloidosis and wild-type transthyretin. Patients with ischemic strokes and amyloidosis have been sporadically reported, however, they are not well summarized. In the present study, a case of cerebral ischemic stroke, secondary to CA was described. This patient presented with dyspnea on exertion, without any evidence of atrial fibrillation. A biopsy revealed deposition of amyloid in the myocardium and Congo Red staining was positive. He suffered from acute infarction of left basal ganglia, resulting from occlusion of the left middle cerebral arterial 6 months prior to admission. However, re-examination of cerebral magnetic resonance imaging in the present hospital revealed an old infarction in the region of the left basal ganglia with a normal appearance of the left middle cerebral artery. Transesophageal echocardiography (TEE) and cardiac magnetic resonance (CMR) both discovered intra-cardiac thrombi, confirming the diagnosis of cardiogenic cerebral embolism. The present study indicates that patients with CA may additionally present with cardiogenic cerebral embolism, and TEE and CMR imaging may help to avoid missing the presence of intra-cardiac thrombi.

Right Ventricle Outflow Obstruction in Biventricular Hypertrophic Cardiomyopathy in Amyloidosis

Light-chain (AL) amyloidosis is the most common type of amyloidosis; cardiac involvement is rare but has a poor prognosis. Biventricular hypertrophic cardiomyopathy is an exceptional finding in amyloidosis and its association with obstructive right ventricular gradient is even rarer. We report the case of a male patient with biventricular hypertrophy suggesting amyloidosis, with an obstructive gradient in the right ventricle.

Diagnostic approach to cardiac amyloidosis: A case report

The authors present a case of systemic amyloidosis with cardiac involvement. We discuss the need for a high level of suspicion to establish a diagnosis, diagnostic techniques and treatment options. Our patient was a 78-year-old man with chronic renal disease and atrial fibrillation admitted with acute decompensated heart failure of unknown cause. The transthoracic echocardiogram revealed severely impaired left ventricular function with phenotypic overlap between hypertrophic and restrictive cardiomyopathy. After an extensive diagnostic workup, which included an abdominal fat pad biopsy, the final diagnosis was amyloidosis.

Usefulness of (99m)Tc-HMDP scintigraphy for the etiologic diagnosis and prognosis of cardiac amyloidosis

BACKGROUND

Amyloidosis is characterized by extracellular deposits of insoluble proteins that cause tissue damage. The three main types are monoclonal light chain (AL), wild-type transthyretin (wt-TTR) and mutated transthyretin (m-TTR) amyloidosis. Cardiac amyloidosis (CA) raises diagnostic challenges.

OBJECTIVE

To assess the diagnostic accuracy of (99m)Tc-HMDP-scintigraphy for typing CA, differentiating CA from non-amyloid left ventricle hypertrophy (LVH), and predicting outcomes.

METHODS

121 patients with suspected CA underwent (99m)Tc-HMDP-scintigraphy in addition to standard investigations.

RESULTS

CA was diagnosed in all AL (n = 14) and wt-TTR (n = 21). Among m-TTR (n = 34), 26 had CA, 4 neuropathy without CA and 4 were asymptomatic carriers. Of the 52 patients with non-amyloid heart disease, 37 had LVH and served as controls. (99m)Tc-HMDP cardiac uptake occurred in all wt-TTR, in m-TTR with CA except two and in one AL. A visual score ≥ 2 was 100% specific for diagnosing TTR-CA. Among TTR-CA, heart-to-skull retention (HR/SR) correlated with CA severity (LVEF and NT-proBNP). Median follow-up was 111 days (50;343). In a multivariate Cox model including clinical, echocardiographic and scintigraphic variables, NYHA III-IV and HR/SR > 1.94 predicted acute heart failure and/or death.

CONCLUSIONS

This preliminary study suggests that (99m)Tc-HMDP-scintigraphy may aid differentiation between transthyretin and AL-CA as well as CA from other LVHs. (99m)Tc-HMDP-scintigraphy appears to provide prognostic information in CA.

Pathophysiology and treatment of cardiac amyloidosis

Amyloid cardiomyopathy should be suspected in any patient who presents with heart failure and preserved ejection fraction. In patients with echocardiographic evidence of ventricular thickening and without a clear history of hypertension, infiltrative cardiomyopathy should be considered. If imaging suggests the presence of amyloid deposits, confirmation by biopsy is required, although endomyocardial biopsy is generally not necessary. Assessment of aspirated subcutaneous fat and bone-marrow biopsy samples verifies the diagnosis in 40-80% of patients, dependent on the type of amyloidosis. Mass spectroscopy can be used to determine the protein subunit and classify the disease as immunoglobulin light-chain amyloidosis or transthyretin-related amyloidosis associated with mutant or wild-type TTR (formerly known as familial amyloid cardiomyopathy and senile cardiac amyloidosis, respectively). In this Review, we discuss the characteristics of cardiac amyloidosis, and present a structured approach to both the assessment of patients and treatment with emerging therapies and organ transplantation.

Guidelines for the prevention of stroke in patients with stroke and transient ischemic attack: a guideline for healthcare professionals from the American Heart Association/American Stroke Association

The aim of this updated guideline is to provide comprehensive and timely evidence-based recommendations on the prevention of future stroke among survivors of ischemic stroke or transient ischemic attack. The guideline is addressed to all clinicians who manage secondary prevention for these patients. Evidence-based recommendations are provided for control of risk factors, intervention for vascular obstruction, antithrombotic therapy for cardioembolism, and antiplatelet therapy for noncardioembolic stroke. Recommendations are also provided for the prevention of recurrent stroke in a variety of specific circumstances, including aortic arch atherosclerosis, arterial dissection, patent foramen ovale, hyperhomocysteinemia, hypercoagulable states, antiphospholipid antibody syndrome, sickle cell disease, cerebral venous sinus thrombosis, and pregnancy. Special sections address use of antithrombotic and anticoagulation therapy after an intracranial hemorrhage and implementation of guidelines.

An unexpected mortality following cardiac surgery: a post-mortem diagnosis of cardiac amyloidosis

Amyloidosis is a rare systemic disease that is notoriously difficult to diagnose early. Cardiac involvement is associated with a poor prognosis. We present the case of a 72-year-old gentleman who underwent elective coronary artery bypass grafting and mitral valve repair. While initially making a good post-operative recovery, a sudden deterioration on post-operative day 3 led to an unexpected mortality. Post-mortem examination demonstrated previously undiagnosed severe systemic amyloidosis, which particularly affected his heart, due to underlying multiple myeloma. It is important to emphasise that due to the absence of the typical findings on routine pre-operative investigations suggestive of cardiac amyloidosis in this patient, cardiac surgeons should be aware that symptoms inconsistent with angiography findings should prompt consideration of amyloidosis. Diagnostic tools including cardiac MRI and ultimately endomyocardial biopsy could then facilitate earlier recognition of this enigmatic disease process.

How to manage primary amyloidosis

Immunoglobulin light chain amyloidosis is a protein deposition disorder where the precursor protein represents a monoclonal immunoglobulin light or heavy chain. Deposition in viscera results in restrictive cardiomyopathy, nephrotic range proteinuria, demyelinating peripheral neuropathy, hepatomegaly and malabsorption syndrome. Diagnosis requires biopsy with Congo red staining. Invasive biopsies are not required generally. It is essential that after a histologic diagnosis is obtained, the tissue is validated to have an immunoglobulin light chain composition so patients are spared unnecessary chemotherapy. The disease prognosis and patient monitoring are linked to serialized measurement of cardiac biomarkers and immunoglobulin-free light chains. Most patients require cytotoxic chemotherapy. For some patients, this therapy involves stem cell collection and myeloablative chemotherapy; for others, chemotherapy includes an alkylator and a corticosteroid; and for some, it involves addition of a novel agent in the form of an immunomodulatory drug or a proteasome inhibitor. Delays in diagnosis continue to be an obstacle to initiating effective therapy. Early mortality rates remain high. Effective chemotherapy can result in reversal of organ dysfunction and recovery. Reductions in light chain production translate to improved survival.

Autoinflammatory diseases and cardiovascular manifestations

Abstract A host of clinical scenarios can be depicted in hereditary autoinflammatory diseases, and the cardiovascular system can also be involved especially in familial Mediterranean fever (FMF), caused by mutations in the MEFV gene, and tumour necrosis factor receptor-associated periodic syndrome (TRAPS), caused by mutations in the TNFRSF1A gene. Pericardial diseases are the most represented cardiovascular abnormalities, though the role of MEFV and TNFRSF1A in the initiation of heart involvement has not been demonstrated formally and will be discussed herein.