Cardiac transplantation for amyloid heart disease: The United Kingdom experience

Role of Autologous Stem Cell Transplantation in Systemic Light Chain Amyloidosis

Systemic light chain (AL) amyloidosis is a multisystem disorder characterized by extracellular deposition of misfolded insoluble amyloid fibrils resulting in progressive organ dysfunction. AL. amyloidosis most commonly affects the heart, kidneys, gastrointestinal tract and peripheral nerves. Early mortality is chiefly determined by the degree of cardiac involvement. The aim of therapy is to rapidly reduce amyloidogenic light chain production by targeting the underlying clonal plasma or lymphoma cell population. High dose therapy with melphalan followed by autologous peripheral blood stem cell transplant (ASCT) continues to remain a highly effective treatment and is considered a standard of care for transplant eligible patients, which offers long term disease control in patients with AL amyloidosis. In recent years, several new therapeutic options have emerged (including anti-CD38 monoclonal antibodies) which are very effective alone or in combination in eradicating clonal plasma cells. In this review, we discuss the role of ASCT in the current setting of a rapidly evolving treatment landscape for patients with AL amyloidosis and provide our practice recommendations.

Cardiac amyloidosis and aortic stenosis: a state-of-the-art review

Cardiac amyloidosis is caused by the extracellular deposition of amyloid fibrils in the heart, involving not only the myocardium but also any cardiovascular structure. Indeed, this progressive infiltrative disease also involves the cardiac valves and, specifically, shows a high prevalence with aortic stenosis. Misfolded protein infiltration in the aortic valve leads to tissue damage resulting in the onset or worsening of valve stenosis. Transthyretin cardiac amyloidosis and aortic stenosis coexist in patients > 65 years in about 4-16% of cases, especially in those undergoing transcatheter aortic valve replacement. Diagnostic workup for cardiac amyloidosis in patients with aortic stenosis is based on a multi-parametric approach considering clinical assessment, electrocardiogram, haematologic tests, basic and advanced echocardiography, cardiac magnetic resonance, and technetium labelled cardiac scintigraphy like technetium-99 m (99mTc)-pyrophosphate, 99mTc-3,3-diphosphono-1,2-propanodicarboxylic acid, and 99mTc-hydroxymethylene diphosphonate. However, a biopsy is the traditional gold standard for diagnosis. The prognosis of patients with coexisting cardiac amyloidosis and aortic stenosis is still under evaluation. The combination of these two pathologies worsens the prognosis. Regarding treatment, mortality is reduced in patients with cardiac amyloidosis and severe aortic stenosis after undergoing transcatheter aortic valve replacement. Further studies are needed to confirm these findings and to understand whether the diagnosis of cardiac amyloidosis could affect therapeutic strategies. The aim of this review is to critically expose the current state-of-art regarding the association of cardiac amyloidosis with aortic stenosis, from pathophysiology to treatment.

Coronary artery bypass grafting for triple vessel disease in cardiac amyloidosis

Cardiac amyloidosis is a rare condition with an estimated incidence of 18-55 per 100 000 person-years. It is associated with either immunoglobulin light chain (AL) or transthyretin amyloid (ATTR), both of which result in a restrictive cardiomyopathy complicated initially by diastolic dysfunction and subsequently followed by biventricular systolic heart failure. Untreated cardiac amyloidosis carries an extremely poor prognosis with an estimated median survival time of less than 1 year in AL and 4 years in ATTR amyloidosis. This is the sixth described report of coronary artery bypass grafting in patients with underlying cardiac amyloidosis.

Implications of Extra-cardiac Disease in Patient Selection for Heart Transplantation: Considerations in Cardiac Amyloidosis

Disease-modifying therapies in both light chain and transthyretin amyloidosis have improved patient functional status and survival. Conceivably, as heart failure may progress despite amyloid therapies, more patients may be considered for heart transplantation. In earlier eras, extra-cardiac amyloid deposits significantly reduced post-heart transplant patient survival and functional status compared to the non-amyloid population. In the modern era, transplant centres have reported improved outcomes in amyloidosis as patient selection has grown more stringent. Importantly, systematic candidate evaluation should assess the degree of extra-cardiac involvement, the effectiveness of disease-modifying therapies and downstream effects on patients' nutrition and frailty. This review outlines such an overall approach while also considering that organ-specific selection criteria may vary between individual transplant centres. A methodical approach to patient evaluation will promote better understanding of the prevalence and severity of extra-cardiac disease in amyloidosis patients referred for heart transplantation and of any disparities in decision outcomes in this population.

Cardiac transplantation in transthyretin amyloid cardiomyopathy: Outcomes from three decades of tertiary center experience

Aims

Transthyretin cardiac amyloidosis (ATTR-CM) is a progressive and fatal cardiomyopathy. Treatment options in patients with advanced ATTR-CM are limited to cardiac transplantation (CT). Despite case series demonstrating comparable outcomes with CT between patients with ATTR-CM and non-amyloid cardiomyopathies, ATTR-CM is considered to be a contraindication to CT in some centers, partly due to a perceived risk of amyloid recurrence in the allograft. We report long-term outcomes of CT in ATTR-CM at two tertiary centers.

Materials and methods and Results

We retrospectively evaluated ATTR-CM patients across two tertiary centers who underwent transplantation between 1990 and 2020. Pre-transplantation characteristics were determined and outcomes were compared with a cohort of non-transplanted ATTR-CM patients. Fourteen (12 male, 2 female) patients with ATTR-CM underwent CT including 11 with wild-type ATTR-CM and 3 with variant ATTR-CM (ATTRv). Median age at CT was 62 years and median follow up post-CT was 66 months. One, three, and five-year survival was 100, 92, and 90%, respectively and the longest surviving patient was Censored > 19 years post CT. No patients had recurrence of amyloid in the cardiac allograft. Four patients died, including one with ATTRv-CM from complications of leptomeningeal amyloidosis. Survival among the cohort of patients who underwent CT was significantly prolonged compared to UK patients with ATTR-CM generally (p < 0.001) including those diagnosed under age 65 years (p = 0.008) or with early stage cardiomyopathy (p < 0.001).

Conclusion

CT is well-tolerated, restores functional capacity and improves prognosis in ATTR-CM. The risk of amyloid recurrence in the cardiac allograft appears to be low.

Outcomes of heart transplantation in cardiac amyloidosis: an updated systematic review

Cardiac amyloidosis is one of the most common infiltrative cardiomyopathies that is characterized by the extracellular deposition of misfolded fibrillar protein. Several studies have previously found that patients with amyloid in the past have performed poorly after heart transplantation. Recent advancements in treatments have been made that have significantly improved outcomes in these patients. The study aimed to evaluate the outcomes of heart transplantation in cardiac amyloidosis. We systematically searched EMBASE, PubMed/MEDLINE, and Cochrane Library databases on 30 December 2021 following the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. We identified 22 studies that examined 42,951 patients with cardiac amyloidosis of which only 1,329 patients underwent isolated heart transplantation. Seven studies reported individual patient data. The results of 123 patients have been pooled for analysis. There were 70 male patients, 45 female patients, and eight patients who did not report their gender. Among the types of amyloids, 63 (51%) patients were found to have light chain amyloidosis (AL) and 33 (27%) patients had transthyretin amyloidosis (ATTR). Only 41 patients (33.3%) reported a monoclonal component. There were 30 patients with AL that underwent autologous hematopoietic stem cell transplant (ASCT). The mean survival of 24 out of 30 patients was 4.33 years. In addition, the reported data include 13 patients requiring intra-aortic balloon pump (IABP), six with cardiac resynchronization therapy (CRT), and four with implantable cardioverter defibrillator (ICD). With the current advancements in treatments in combination with a multidisciplinary approach and careful patient selection, patients undergoing heart transplantation for amyloidosis may have encouraging results in the current era. Further studies will be needed to evaluate the outcomes of heart transplantation in amyloidosis patients now that several advances have been made in the field.

Trends and Outcomes of Patients with Amyloid Cardiomyopathy Listed for Heart Transplantation

BACKGROUND

Heart transplantation in patients with amyloid cardiomyopathy (ACM) has been historically underutilized due to the risk of amyloid recurrence.

METHODS

Using data from the United Network for Organ Sharing database on patients listed for single-organ heart transplant between 2010 and 2019, we evaluated trend in heart transplant, and compared waitlist mortality and graft survival between patients with ACM and dilated cardiomyopathy (DCM). Also, we evaluated for independent predictors of outcomes.

RESULTS

Over the study period, 411 ACM adult patients with ACM were added to the heart transplant waitlist. In the propensity-matched cohorts, the rates of waitlist mortality was significantly higher for ACM compared to DCM (HR=1.75, 95%CI=1.16-2.65). Over the study period, 330 ACM patients underwent heart transplant. The number of transplants increased from 22 in 2010 to 59 in 2019 (168% increase). The 5-year graft survival rate was however significantly worse for ACM (78%) compared to DCM (82%) (HR=1.46, 1.03-2.08). We identified two predictors of graft failure among ACM patients, namely, renal failure requiring dialysis (HR=5.4, 1.6-17) and prior history of malignancy (HR=1.6, 1.0-28). ACM patients with neither of the risk factor had 5-year graft survival of 82% that is comparable to DCM (HR=1.28, 0.90-1.91). On the other hand, ACM patients with either of the risk factor had worse 5-year graft survival of 62% (HR=2.44, 1.39-4.28).

CONCLUSION

Increasing number of ACM patients are undergoing heart transplant. Although ACM patients experience higher waitlist mortality and worse graft survival compared to DCM, selecting carefully screened ACM patients may result in improved outcomes following heart transplant.

State-of-the-art review on management of end-stage heart failure in amyloidosis: transplant and beyond

Cardiac involvement occurs in light-chain (AL), transthyretin wild-type (wtATTR), and hereditary (hATTR) amyloidosis; other types of amyloidosis account for < 5% of all cardiac amyloidosis (CA). CA can present subclinically on screening, insidiously with symptoms such as exertional dyspnea, or abruptly as cardiogenic shock. Initially, CA patients were thought to be poor candidates for transplant due to short long-term survival; however, there is a marked improvement in heart and multi-organ transplant outcomes over the past 10 years with newer treatments and improvements in support with temporary and durable mechanical circulatory support while awaiting transplant. Patients with AL CA were reported to have worse post-OHT outcomes than patients with ATTR CA, but this gap is quickly closing with improved patient selection, novel chemotherapeutics, and perhaps with selected use of bone marrow transplantation. Waitlist mortality and transplantation rates have markedly improved for CA after the United Network for Organ Sharing (UNOS) policy change in October 2018. In this review, we will evaluate contemporary data from the last 5 years on advances in the field of transplantation and mechanical circulatory support in this patient population.

Misconceptions and Facts About Cardiac Amyloidosis

Cardiac amyloidosis is an important clinical entity associated with significant morbidity and mortality. Although the signs and symptoms can be apparent early in the disease course, diagnoses are often made late because of inadequate recognition. A diagnosis of cardiac amyloidosis requires careful scrutiny of a patient's symptoms, an electrocardiogram, and imaging studies, including echocardiography and magnetic resonance imaging. Further evaluation is required through the measurement of serum and urine light chains and the use of bone scintigraphy imaging to differentiate transthyretin amyloidosis from light-chain cardiac amyloidosis. The available treatments have expanded tremendously in recent years and have improved outcomes in the population with this disorder. Thus, it has become increasingly important to diagnose cardiac amyloidosis and provide timely therapies. This article will clarify the various misconceptions about cardiac amyloidosis and provide a framework for primary care providers to better identify this disease in their practice.

Cardiac Transplantation and Mechanical Circulatory Support in Amyloidosis

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Cardiac transplantation for amyloidosis was once considered contraindicated owing to unacceptably high morbidity/mortality rates.

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Increased therapeutic options for AL and ATTR amyloidosis and improved pre-transplantation screening practices have led to markedly improved transplant outcomes over the past 10-15 years.

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Mechanical circulatory support options remain limited but can be considered in selected patients, particularly for those with larger ventricular cavities.

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Transplant prioritization rules may need to be reconsidered for amyloidosis patients to adequately prioritize AL amyloidosis patients, who are at increased risk of pre-transplantation mortality.

Cardiac transplantation outcomes in patients with amyloid cardiomyopathy

OBJECTIVE

Amyloid cardiomyopathy (ACM) is a progressive and life-threatening disease caused by abnormal protein deposits within cardiac tissue. The most common forms of ACM are caused by immunoglobulin derived light chains (AL) and transthyretin (TTR). Orthotopic heart transplantation (OHT) remains the definitive treatment for patients with end stage heart failure. In this study, we perform a contemporary multicenter analysis evaluating post OHT survival in patients with ACM.

METHODS

We conducted a multicenter analysis of 40,044 adult OHT recipients captured in the United Network for Organ Sharing (UNOS) registry from 1987-2018. Patients were characterized as ACM or non-ACM. Baseline characteristics were obtained, and summary characteristics were calculated. Outcomes of interest included post-transplant survival, infection, treated rejection, and the ability to return to work. Racial differences in OHT survival were also analyzed. Unadjusted associations between ACM and non-ACM survival were determined using the Kaplan-Meier estimations and confounding was addressed using multivariable Cox proportional hazards models.

RESULTS

Three hundred ninety-eight patients with a diagnosis of ACM were identified of which 313 underwent heart only OHT. ACM patients were older (61 vs 53; P < .0001) and had a higher proportion of African Americans (30.7% vs 17.6%; P < .0001). Median survival for ACM was 10.2 years vs 12.5 years in non-ACM (P = .01). After adjusting for confounding, ACM patients had a higher likelihood of death post-OHT (HR 1.39 CI: 1.14, 1.70; P = .001). African American ACM patients had a higher likelihood of survival compared to White ACM patients (HR 0.51 CI 0.31-0.85; P = .01). No difference was observed in episodes of treated rejection (OR 0.63 CI 0.23, 1.78; P = .39), hospitalizations for infections (OR 1.24 CI: 0.85, 1.81; P = .26), or likelihood of returning to work for income (OR 1.23 CI: 0.84, 1.80; P = .30).

CONCLUSIONS

In this analysis of OHT in ACM, ACM was associated with a higher likelihood of post-OHT mortality. Racial differences in post-OHT were observed with African American patients with ACM having higher likelihood of survival compared to White patients with ACM. No differences were observed in episodes of treated rejection, hospitalization for infection, or likelihood to return to work for income.

Cardiac Transthyretin Amyloidosis: A Nuclear Medicine Leading Role. Situation in a Spanish Center and "State of the Art" in Nuclear Medicine

PURPOSE

Amyloidosis is a heterogeneous group of diseases caused by abnormal extracellular deposition of insoluble proteins and can involve myocardium. One of the causes of myocardial involvement is TTR amyloidosis. Our objective has been to evaluate the situation of cardiac amyloidosis (CA) in our center and the role of nuclear medicine, and to review the state of the art of nuclear medicine in this entity.

PATIENTS AND METHODS

We have evaluated retrospectively 186 patients with clinical suspicion of CA and analyzed the clinical characteristics, free light chains and immunofixation in serum and/or urine, and the most relevant biomarkers associated with transthyretin CA (C-ATTR) of these patients and compared them with the results of the 99mTc-DPD scintigraphy.

RESULTS

We have verified the growing bibliographic evidence concerning C-ATTR. A total of 51 scintigraphies (27.4%) were positive, 2 (1.1%) indeterminate and 133 (71.5%) negative according to the Perugini score. ATTR was diagnosed in 22 (11.8%; 77.3% males; mean age, 79.4 years). Of these, 12 (75% men; 82.3 years) were ATTRwt (wild-type or age-associated) patients, 2 (50% men; 52 years) experienced ATTRv (variant or hereditary), and 8 (87.5% men; 82.3 years) were not classified because of the absence genetic test. The origin of amyloidosis could not be determined in 31 (16.7%; 80.7% males; 84.5 years). In 29 of them (93.6%), it was because there was no study of free light chains or immunofixation.

CONCLUSIONS

Nuclear medicine is playing an increasing role in the diagnosis and classification of CA. However, the monitoring of these is still patchy.

Intermediate-term outcomes of heart transplantation for cardiac amyloidosis in the current era

BACKGROUND

Cardiac amyloidosis (CA) has been historically noted with poor outcomes after heart transplant (HTx). However, strict patient selection, appropriate multi-organ transplant, and aggressive post-transplant therapy can result in favorable outcomes. We present the experience in the largest single-center cohort of CA patients post-HTx in the recent era.

METHODS

Between January 2010 and December 2018, 51 CA patients underwent HTx-13 light-chain amyloidosis (AL) and 38 transthyretin amyloidosis (ATTR), 49 were included. Endpoints included 3-year survival, freedom from cardiac allograft vasculopathy (CAV), and freedom from non-fatal major adverse cardiac events (NF-MACE).

RESULTS

Overall 3-year survival was 81.6% (69.2% for AL and 86% for ATTR) and was comparable to survival for patients transplanted for non-amyloid restrictive cardiomyopathy (RCM) in the same period (89%, p = .46). Three-year freedom from CAV (84% vs. 89%, p = .98), NF-MACE (82% vs. 83%, p = .96), and any-treated rejection (95% vs. 89%, p = .54) were also comparable in both groups. No recurrence in amyloid was noted in endomyocardial biopsies. Six patients (46%) with AL amyloidosis underwent autologous stem cell transplant 1-year post-HTx, and two patients (8%) with variant ATTR-CA underwent combined heart-liver transplant due to cardiac cirrhosis.

CONCLUSION

In the current era, both AL and ATTR cardiac amyloidosis patients have acceptable outcomes after heart transplantation.

Emerging therapy in light-chain and acquired transthyretin-related amyloidosis: an Italian single-centre experience in heart transplantation

AIMS

The prognosis for patients affected by light-chain cardiac amyloidosis and acquired transthyretin-related (TTR) amyloidosis is poor. Heart transplantation (HTx) could improve prognosis also enabling autologous stem cell transplantation (ASCT) in the first group.

METHODS AND RESULTS

A total of 36 patients affected by systemic amyloidosis have been referred to our centre from 2009 to 2019. Of these, nine had cardiac involvement: seven by light-chain amyloidosis and two by acquired TTR amyloidosis. None died while waiting for HTx. A specific internal protocol useful to select candidates and to monitor the organ involvement after HTx was developed. Median age at diagnosis was 54 years and 66% were male. The most common short-term complication after HTx was renal failure (44%), followed by acute cardiac rejection more than 2R (22%). ASCT was performed in six out of seven light-chain cardiac amyloidosis patients, with a median time of 6 months after HTx. Two patients affected by light-chain cardiac amyloidosis died due to amyloidosis relapse: one before undergoing ASCT. After a median follow-up of 31 (7-124) months, 1- and 5-year survival was 88 and 66% in the cardiac light-chain amyloidosis group. Conversely, 1- and 5-year survival was 100% in the acquired TTR amyloidosis group.

CONCLUSION

HTx may represent a valuable option in carefully selected patients. ASCT after HTx is an effective treatment that could decrease amyloidosis relapse in light-chain cardiac amyloidosis patients. A multidisciplinary approach is mandatory to select the best candidates and to obtain the most effective results with a specific surveillance follow-up protocol.

Drug Discovery and Development in Rare Diseases: Taking a Closer Look at the Tafamidis Story

Rare diseases are increasingly recognized as a global public health priority. Governments worldwide currently provide important incentives to stimulate the discovery and development of orphan drugs for the treatment of these conditions, but substantial scientific, clinical, and regulatory challenges remain. Tafamidis is a first-in-class, disease-modifying transthyretin (TTR) kinetic stabilizer that represents a major breakthrough in the treatment of transthyretin amyloidosis (ATTR amyloidosis). ATTR amyloidosis is a rare, progressive, and fatal systemic disorder caused by aggregation of misfolded TTR and extracellular deposition of amyloid fibrils in various tissues and organs, including the heart and nervous systems. In this review, we present the successful development of tafamidis spanning 3 decades, marked by meticulous laboratory research into disease mechanisms and natural history, and innovative clinical study design and implementation. These efforts established the safety and efficacy profile of tafamidis, leading to its regulatory approval, and enabled post-approval initiatives that further support patients with ATTR amyloidosis.

Solid Organ Transplantation

Please add expansion for AL. Hematologic disease control combined with solid organ transplantation can result in long-term survival in selected patients with light chain (AL) amyloidosis and limited other organ involvement. Restoration of critical cardiac function with organ transplantation can render patients eligible for effective disease-directed therapies, including high-dose therapy and autologous stem cell transplantation. Access to directed-donor organs, exchange programs for renal transplantation, and extended-donor organs for cardiac transplantation improves the availability of organs for patients with AL amyloidosis. Disease recurrence in the graft and progression in other organs remain concerns but often can be managed with a variety of effective plasma cell-directed therapies.

Outcomes of Heart Transplantation in Cardiac Amyloidosis Patients: A Single Center Experience

BACKGROUND

Indications for heart transplantation are expanding to include amyloid light chain (AL) and transthyretin-related (TTR) amyloidosis. Previously, AL amyloid had been a contraindication to heart transplantation given inferior outcomes. These patients typically have biventricular failure requiring mechanical circulatory support (MCS). We report the outcomes of patients with end-stage cardiac amyloidosis who underwent cardiac transplantation, including some who were bridged to transplantation with a durable biventricular MCS METHODS: The records for patients with cardiac amyloidosis who underwent cardiac transplant between 2010 and 2018 were reviewed. Primary endpoint was post-transplant 1-year survival. Secondary endpoints included 1-year freedom from cardiac allograft vasculopathy (as defined by stenosis ≥ 30% by angiography), nonfatal major adverse cardiac events (myocardial infarction, new congestive heart failure, percutaneous coronary intervention, implantable cardioverter defibrillator/pacemaker implant, stroke), and any rejection.

RESULTS

A total of 46 patients received heart transplantation with a diagnosis of either AL or TTR amyloidosis. Of these, 7 patients were bridged to transplantation with a durable biventricular MCS device (6 AL, 1 TTR) and 39 patients were transplanted without MCS bridging. The MCS group consisted of 5 total artificial hearts and 2 biventricular assist devices. The 1-year survival was 91% for the entire cohort, 83% for those with AL amyloidosis, 94% for those with TTR amyloidosis, and 86% for those who received MCS bridging.

CONCLUSIONS

Cardiac transplantation can be safely performed in selected amyloidosis patients with reasonable short-term outcomes. Those bridged to transplantation with biventricular MCS appear to have short-term outcomes similar to those transplanted without MCS. Larger numbers and longer observation are required to confirm these findings.

Solid Organ Transplantation in Amyloidosis

Amyloidosis comprises a diverse group of diseases characterized by misfolding of precursor proteins which eventually form amyloid aggregates and preceding intermediaries, which are deposited in target tissues causing progressive organ damage. In all forms of amyloidosis, vital organs may fail; depending on the specific amyloidosis type, this may occur rapidly or progress slowly. Beyond therapies to reduce the precursor protein (chemotherapy for light chain [AL] amyloidosis, anti-inflammatory therapy in serum A amyloid-osis [AA], and antisense RNA therapy in transthyretin amyloidosis [ATTR]), organ transplantation may also be a means to reduce amyloidogenic protein, e.g., in types of amyloid-osis in which the variant precursor is produced by the liver. Heart transplantation is a life-saving approach to the treatment of patients with advanced cardiac amyloidosis; however, amyloidosis may still be considered a contraindication to the procedure despite data supporting improved outcomes, similar to patients with other indications. Kidney transplantation is associated with particularly favorable outcomes in patients with amyloidosis, especially if the precursor protein has been eliminated. Overall, outcomes of solid organ transplantation are improving, but more data are needed to refine the selection criteria and the timing for organ transplantation, which should be performed in highly experienced centers involving multidisciplinary teams with close patient follow-up to detect amyloid recurrence.

Supportive Care in AL Amyloidosis

Immunoglobulin light-chain (AL) amyloidosis is a systemic disease characterized by the production and deposition of light chain-derived amyloid fibrils in different organs. Prompt treatment directed to the underlying plasma cell clone is crucial in order to achieve a rapid, deep and durable hematologic response. The decrease in the production of the amyloidogenic light chains is a required condition to obtain the organ response, which is commonly delayed. Meanwhile, supportive treatment is aimed to maintain quality of life of these patients and preserve their involved organs' function. From simple measures, such as salt restriction or compressive stockings, to very complex interventions, such as heart transplantation in very selected patients with isolated severe cardiac involvement, this supportive care is essential and has to be necessarily included in the multidisciplinary management of this disease.

AL Amyloidosis for the Cardiologist and Oncologist: Epidemiology, Diagnosis, and Management

AL amyloidosis results from clonal production of immunoglobulin light chains, most commonly arising from a clonal plasma cell disorder. Once considered a nearly uniformly fatal disease, prognosis has improved markedly over the past 15 years, predominantly because of advances in light chain suppressive therapies. Cardiac deposition of amyloid fibrils is common, and the severity of cardiac involvement remains the primary driver of prognosis. Improvements in chemotherapy/immunotherapy have prompted a reassessment of the role of advanced cardiac therapies previously considered contraindicated in most patients, including the role of implantable cardioverter-defibrillators and cardiac transplantation. This state-of-the-art review highlights the current state of the field, including diagnosis, prognosis, and hematologic- and cardiac-specific therapies.

Outcomes After Cardiac Transplant for Wild Type Transthyretin Amyloidosis

BACKGROUND

The true prevalence of heart failure due to wild type transthyretin amyloidosis (ATTRwt) is likely underestimated. There is a paucity of data with regard to the management of ATTRwt-related advanced heart failure and the natural history of extracardiac ATTRwt.

METHODS

We conducted a retrospective cohort study of patients undergoing cardiac transplant (HTx) for ATTRwt at a single institution. Comprehensive clinical data, including baseline hemodynamic and echocardiographic characteristics, and posttransplant outcomes, were obtained.

RESULTS

Seven patients with ATTRwt underwent HTx between 2007 and 2015. All patients were male with a mean age of 66 ± 9. Patients had a reduced ejection fraction (mean, 37 ± 14%) and elevated filling pressures pre-HTx (mean pulmonary capillary wedge pressure 22 ± 7 mm Hg) before HTx. Three-year survival was 100%; 1 patient died of pancreatic cancer 45 months post-HTx (1 death per 30.8 patient-years). Oxygen consumption (Δ +6.8 ± 4.9 mL·kg·min) and 6-minute walk distances (Δ +189 ± 60 m) improved. Symptomatic gastrointestinal involvement (n = 2) and peripheral nerve involvement (n = 4) by ATTRwt developed late.

CONCLUSIONS

This is the first report of a series of ATTRwt patients receiving HTx in which excellent outcomes are demonstrated. Although cardiac death is averted, systemic manifestations of ATTRwt may develop posttransplantation.

Heart transplantation in cardiac amyloidosis

"Cardiac amyloidosis" is the term commonly used to reflect the deposition of abnormal protein amyloid in the heart. This process can result from several different forms, most commonly from light-chain (AL) amyloidosis and transthyretin (ATTR) amyloidosis, which in turn can represent wild-type (ATTRwt) or genetic form. Regardless of the origin, cardiac involvement is usually associated with poor prognosis, especially in AL amyloidosis. Although several treatment options, including chemotherapy, exist for different forms of the disease, cardiac transplantation is increasingly considered. However, high mortality on the transplantation list, typical for patients with amyloidosis, and suboptimal post-transplant outcomes are major issues. We are reviewing the literature and summarizing pros and cons of listing patients with amyloidosis for cardiac or combine organ transplant, appropriate work-up, and intermediate and long-term outcomes. Both AL and ATTR amyloidosis are included in this review.

Newer Therapies for Amyloid Cardiomyopathy

The heart and the kidneys are the most commonly involved organs in systemic amyloidosis. Cardiac involvement is associated with an increased morbidity, treatment intolerance, and poorer overall survival. The most common types of amyloidosis that are associated with cardiac involvement include light chain (AL) amyloidosis and transthyretin (TTR) amyloidosis (both mutant and wild type). The traditional first-line treatment for AL amyloidosis includes alkylator-based chemotherapy or high-dose melphalan followed by autologous stem cell transplantation (ASCT). Novel agents, including proteasome inhibitors, immunomodulators, and monoclonal antibodies, have shown promising activity in both frontline and relapsed settings. Orthotopic heart transplantation (OHT) followed by ASCT has led to superior outcomes compared to OHT alone. Orthotopic liver transplantation (OLT) is the first-line treatment for TTR amyloidosis. However, progression of cardiac amyloidosis after OLT is often noted due to deposition of wild TTR. Combined OLT and OHT also has a role in treatment and leads to superior outcomes in carefully selected candidates. Pharmacologic agents, including diflunisal, tafamidis, small interfering ribonucleic acid, and doxycycline, have shown promising activity in stabilizing TTR from misfolding into fibrils and are being actively investigated. Best supportive care and management of heart failure symptoms with diuretics are a mainstay of treatment in all cardiac amyloidosis subtypes. Robust data on the benefit of angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, or beta blockers in amyloid cardiomyopathy is lacking.

Stem cell transplantation for immunoglobulin light chain amyloidosis

Systemic chemotherapy aimed at eradicating transformed plasma cells is the mainstay of treatment for immunoglobulin light chain amyloidosis (AL). Autologous stem cell transplantation (SCT) is a highly effective treatment for AL and can lead to long term survival in excess of 10 years in patients who achieve complete remission. Since AL is a unique disease characterized by multiple organ dysfunction, SCT poses unique challenges in this disease. Morbidity and mortality of SCT has remarkably improved over time primarily due to careful selection of patients and evolution of predictive and prognostic models based on serum immunoglobulin light chains and cardiac biomarkers. In this review we focus on the historical evolution of SCT as a treatment for AL and unique challenges it poses in the management of this rare disease and provide guidelines for managing these challenges.

Emerging Advances in the Management of Cardiac Amyloidosis

Amyloidosis is a disease in which proteins misfold, aggregate into fibrils, and deposit extracellularly disrupting organ architecture and function. There are two main types which affect the heart: light chain (AL) amyloidosis and transthyretin cardiac amyloidosis (ATTR). There is a misconception that cardiac amyloidosis has no effective treatment options. However, over the past decade, there has been extensive research and drug development. Outcomes are improving in AL amyloidosis with evolving chemotherapeutic regimens and novel monoclonal antibodies. In ATTR, therapies that decrease protein production, prevent dissociation, and promote clearance have the potential to slow or even halt a disease which is uniformly fatal. Selected patients may be candidates for heart and/or stem cell transplant and should be promptly referred to an experienced amyloid program. Herein, we discuss the emerging advances for the treatment of cardiac amyloidosis.

Natural history and therapy of AL cardiac amyloidosis

The natural history of immunoglobulin light chain associated amyloidosis (AL) is determined by the extent of cardiac involvement. Patients with cardiac AL and symptomatic heart failure have a median survival of approximately six months without successful treatment of the underlying plasma cell disorder The outcome in cardiac AL is determined by both the severity of cardiac involvement and the response to treatment. Staging systems using cardiac biomarkers, including NT- proBNP and troponin, have been found to be powerful predictors of prognosis and are used to guide treatment. Arrhythmias are common in cardiac AL and may lead to acute hemodynamic compromise. Sudden cardiac death, often due to pulseless electrical activity, is an important cause of early mortality. Supportive therapy for heart failure is usually limited to diuretics. Beta-blockers, ACE-inhibitors, and angiotensin receptor blockers are poorly tolerated in cardiac AL and should be avoided. Cardiac transplantation is controversial and reserved for highly selected patients with limited extracardiac involvement. The primary target of treatment in cardiac AL is obliteration of the plasma cell clone, using chemotherapy alone or combined with autologous stem cell transplantation. Despite the risk of early mortality, overall survival has improved with advances in disease modifying therapy. Earlier diagnosis and treatment of cardiac AL is crucial to improving survival.

Evolving landscape in the management of transthyretin amyloidosis

Transthyretin (TTR) amyloidosis (ATTR amyloidosis) is a multisystemic, multigenotypic disease resulting from deposition of insoluble ATTR amyloid fibrils in various organs and tissues. Although considered rare, the prevalence of this serious disease is likely underestimated because symptoms can be non-specific and diagnosis largely relies on amyloid detection in tissue biopsies. Treatment is guided by which tissues/organs are involved, although therapeutic options are limited for patients with late-stage disease. Indeed, enthusiasm for liver transplantation for familial ATTR amyloidosis with polyneuropathy was dampened by poor outcomes among patients with significant neurological deficits or cardiac involvement. Hence, there remains an unmet medical need for new therapies. The TTR stabilizers tafamidis and diflunisal slow disease progression in some patients with ATTR amyloidosis with polyneuropathy, and the postulated synergistic effect of doxycycline and tauroursodeoxycholic acid on dissolution of amyloid is under investigation. Another therapeutic approach is to reduce production of the amyloidogenic protein, TTR. Plasma TTR concentration can be significantly reduced with ISIS-TTR(Rx), an investigational antisense oligonucleotide-based drug, or with patisiran and revusiran, which are investigational RNA interference-based therapeutics that target the liver. The evolving treatment landscape for ATTR amyloidosis brings hope for further improvements in clinical outcomes for patients with this debilitating disease.

Novel strategies for the diagnosis and treatment of cardiac amyloidosis

Systemic amyloidoses are rare, complex diseases caused by misfolding of autologous protein. The presence of heart involvement is the most important prognostic determinant. The diagnosis of amyloid cardiac involvement relies on echocardiography and magnetic resonance imaging, while scintigraphy with bone tracers is helpful in differentiating light chain amyloidosis from other types of amyloidosis involving the heart. Although these diseases are fatal, effective treatments exist that can alter their natural history, provided that they are started before irreversible cardiac damage has occurred. Refined diagnostic techniques, accurate patients' stratification based on biomarkers of cardiac dysfunction, the availability of novel, more powerful drugs, and ultimately, the unveiling of the cellular mechanisms of cardiac damage created a favorable environment for a dramatic improvement in the treatment of this disease that we expect in the next few years.

Cardiac Amyloidosis Presenting With Cardiogenic Shock

Cardiac amyloidosis is an infiltrative disorder of the myocardium. It is the result of one of 4 types of amyloidosis: primary systemic (immunoglobulin light chain), secondary, familial (hereditary), or senile. Cardiac amyloidosis ultimately causes congestive heart failure due to irreversible restrictive cardiomyopathy. Because of the rapid progression of the disease, early recognition and determination of underlying etiology are important for tailored therapy. Current interventions range from conservative heart failure management to autologous stem cell and heart transplantation. We present a case of cardiac amyloidosis accompanying undiagnosed multiple myeloma to illustrate the rapid progression of the disease and the complexities of diagnosing and treating this disorder.

The transthyretin amyloidoses: advances in therapy

There are two forms of transthyretin (TTR) amyloidosis: non-hereditary and hereditary. The non-hereditary form (ATTRwt) is caused by native or wild-type TTR and was previously referred to as senile systemic amyloidosis. The hereditary form (ATTRm) is caused by variant TTR which results from a genetic mutation of TTR. The predominant effect of ATTRwt amyloidosis is on the heart, with patients having a greater left ventricular wall thickness at presentation than the devastating form which is light chain (AL) amyloidosis. ATTRm amyloidosis is broadly split into two categories: a type that predominantly affects the nervous system (often called familial amyloid polyneuropathy (FAP)) and one with a predilection for the heart (often called familial amyloid cardiomyopathy (FAC)). Approximately half of all TTR mutations known to express a clinical phenotype cause a cardiomyopathy. Since the introduction of orthotopic liver transplantation for ATTRm amyloidosis in 1991, several additional therapies have been developed. These therapies aim to provide a reduction or elimination of TTR from the plasma (through genetic approaches), stabilisation of the TTR molecule (to prevent deposition) and dissolution of the amyloid matrix. We describe the latest developments in these approaches to management, many of which are also applicable to wild-type amyloidosis.

Outcomes after heart transplantation for amyloid cardiomyopathy in the modern era

We conducted a review of patients undergoing heart transplantation (HT) at our institution for amyloid cardiomyopathy (ACM) between 2008 and 2013. Complete follow-up was available for all patients. Nineteen patients with ACM underwent HT during the study period, accounting for 9.4% of all HT performed at our institution during this period. Amyloid subtype was light chain (AL) in 9 patients and transthyretin (ATTR) in 10 (2 wild-type, 7 familial, 1 unknown). Eight of nine patients with AL amyloidosis began chemotherapy prior to HT, six have resumed chemotherapy since HT, and five have undergone autologous stem cell transplantation. Most recent free light chain levels in AL patients decreased by a median of 85% from peak values. Only one patient developed recurrent graft amyloidosis, occurring at 3.5 years post-HT and asymptomatic. After a median follow-up of 380 days, 17 (89.5%) patients are alive. To our knowledge, this is the largest single-center series reported of ACM patients undergoing HT in the modern era. Our results suggest that acceptable outcomes following HT can be achieved in the short-to-intermediate term and that this is a feasible option for end-stage ACM with careful patient selection and aggressive control of amyloidogenic light chains in AL patients.

Morphologic features of the recipient heart in patients having cardiac transplantation and analysis of the congruence or incongruence between the clinical and morphologic diagnoses

Cardiac transplantation (CT) has been one of the great medical advances of the last nearly 50 years. We studied the explanted hearts of 314 patients having CT at Baylor University Medical Center Dallas from 1993 to 2012, and compared the morphologic diagnoses to the clinical diagnoses before CT. Among the 314 patients the morphologic and clinical diagnoses were congruent in 272 (87%) and incongruent in 42 (13%). Most of the incongruity occurred among the 166 patients with non-ischemic cardiomyopathy (non-IC) (36/166 [22%]), and of that group the major incongruity occurred among the patients with hypertrophic cardiomyopathy (7/17 [41%]), non-compaction left ventricular cardiomyopathy (NCLVC) (3/3 [100%]), mononuclear myocarditis (3/3 [100%]), arrhythmogenic right ventricular cardiomyopathy (ARVC) (4/4 [100%]), and cardiac sarcoidosis (8/8 [100%]). The phrase "non-IC" is a general term that includes several subsets of cardiac diseases and simply means "insignificant narrowing of 1 or more of the epicardial coronary arteries," but it does not specify the specific cause of the heart failure leading to CT. A number of cardiac illustrations are provided to demonstrate the morphologic variability occurring among the patients with IC and non-IC.

Isolated heart transplantation for familial transthyretin (TTR) V122I cardiac amyloidosis

Transthyretin (TTR) cardiac amyloidosis is characterized by deposition of either mutant or wild type TTR amyloid protein in the myocardium ultimately leading to progressive cardiomyopathy and heart failure. The most common TTR gene mutation that leads to TTR cardiac amyloidosis is the valine-to-isoleucine substitution at position 122 (V122I or Ile122). Currently, the only definitive treatment suggested for mutant TTR cardiac amyloidosis is the combined or sequential liver-heart transplantation in eligible patients, since liver is the source of TTR production. Here, we report a case of heterozygous Val122L mutated TTR-related cardiac amyloidosis treated with isolated heart transplantation with no recurrence of amyloid in the cardiac allograft and no systemic abnormalities 5 years after heart transplantation. Abbreviations MMF mycophenolate mofetil NYHA New York Heart Association TTR transthyretin VE minute ventilation.

Update on treatment of light chain amyloidosis

Light chain amyloidosis is the most common type of amyloidosis as a consequence of protein misfolding of aggregates composed of amyloid fibrils. The clinical features are dependent on the organs involved, typically cardiac, renal, hepatic, peripheral and autonomic neuropathy and soft tissue. A tissue biopsy or fat aspirate is needed to confirm the presence/type of amyloid and prognostic tools are important in a risk stratified approach to treatment. Autologous stem cell transplant eligibility should be assessed at baseline, weighing the reversible or non-reversible contraindications, toxicity of treatment and chemotherapy alternatives available. Chemotherapy options include melphalan, thalidomide, bortezomib, lenalidomide, bendamustine in combination with dexamethasone. Many studies have explored these treatment modalities, with ongoing debate about the optimal first line and sequential treatment thereafter. Attaining a very good partial response or better is the treatment goal coupled with early assessment central to optimizing treatment. One major challenge remains increasing the awareness of this disease, frequently diagnosed late as the presenting symptoms mimic many other medical conditions. This review focuses on the treatments for light chain amyloidosis, how these treatments have evolved over the years, improved patient risk stratification, toxicities encountered and future directions.