Waitlist Mortality of Patients With Amyloid Cardiomyopathy who Are Listed for Heart Transplantation and Implications for Organ Allocation

Prognosis after heart transplant in patients with hypertrophic and restrictive cardiomyopathy. A nationwide registry analysis

INTRODUCTION AND OBJECTIVES

Posttransplant outcomes among recipients with a diagnosis of hypertrophic cardiomyopathy (HCM) or restrictive cardiomyopathy (RCM) remain controversial.

METHODS

Retrospective analysis of a nationwide registry of first-time recipients undergoing isolated heart transplant between 1984 and 2021. One-year and 5-year mortality in recipients with HCM and RCM were compared with those with dilated cardiomyopathy (DCM).

RESULTS

We included 3703 patients (3112 DCM; 331 HCM; 260 RCM) with a median follow-up of 5.0 [3.1-5.0] years. Compared with DCM, the adjusted 1-year mortality risk was: HCM: HR, 1.38; 95%CI, 1.07-1.78; P=.01, RCM: HR, 1.48; 95%CI, 1.14-1.93; P=.003. The adjusted 5-year mortality risk was: HCM: HR, 1.17; 95%CI, 0.93-1.47; P=.18; RCM: HR, 1.52; 95%CI, 1.22-1.89; P<.001. Over the last 20 years, the RCM group showed significant improvement in 1-year survival (adjusted R2=0.95) and 5-year survival (R2=0.88); the HCM group showed enhanced the 5-year survival (R2=0.59), but the 1-year survival remained stable (R2=0.16).

CONCLUSIONS

Both RCM and HCM were linked to a less favorable early posttransplant prognosis compared with DCM. However, at the 5-year mark, this unfavorable difference was evident only for RCM. Notably, a substantial temporal enhancement in both early and late mortality was observed for RCM, while for HCM, this improvement was mainly evident in late mortality.

Cardiac Amyloidosis: Clinical Features, Pathogenesis, Diagnosis, and Treatment

Cardiac amyloidosis is a type of amyloidosis that deserves special attention as organ involvement significantly worsens the prognosis. Cardiac amyloidosis can be grouped under three main headings: immunoglobulin light chain (AL) amyloidosis that is dependent on amyloidogenic monoclonal light chain production; hereditary Transthyretin (TTR) amyloidosis that results from accumulation of mutated TTR; and wild-type (non-hereditary) TTR amyloidosis formerly known as senile amyloidosis. Although all three types cause morbidity and mortality due to severe heart failure when untreated, they contain differences in their pathogenesis, clinical findings, and treatment. In this article, the clinical features, pathogenesis, diagnosis, and treatment methods of cardiac amyloidosis will be explained with an overview, and an awareness will be raised in the diagnosis of this disease.

A Review of Cardiac amyloidosis: Presentation, Diagnosis, and Treatment

Amyloidosis is a group of disorders that can affect almost any organ due to the misfolding of proteins with their subsequent deposition in various tissues, leading to various disease manifestations based on the location. When the heart is involved, amyloidosis can manifest with a multitude of presentations such as heart failure, arrhythmias, orthostatic hypotension, syncope, and pre-syncope. Diagnosis of cardiac amyloidosis can be difficult due to the non-specific nature of symptoms and the relative rarity of the disease. Amyloidosis can remain undiagnosed for years, leading to its high morbidity and mortality due to this delay in diagnosis. Newer imaging modalities, such as cardiac magnetic resonance imaging, advanced echocardiography, and biomarkers, make a timely cardiac amyloidosis diagnosis more feasible. Many treatment options are available, which have provided new hope for this patient population. This manuscript will review the pathology, diagnosis, and treatment options available for cardiac amyloidosis and provide a comprehensive overview of this complicated disease process.

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 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.

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.

Changes in heart transplant waitlist and posttransplant outcomes in patients with restrictive and hypertrophic cardiomyopathy with the new heart transplant allocation system

Historically, patients with restrictive (RCM) and hypertrophic cardiomyopathy (HCM) experienced longer wait-times for heart transplant (HT) and increased waitlist mortality. Recently, a new HT allocation system was implemented in the United States. We sought to determine the impact of the new HT system on RCM/HCM patients. Adult patients with RCM/HCM listed for HT between November 2015 and September 2019 were identified from the UNOS database. Patients were stratified into two groups: old system and new system. We identified 872 patients who met inclusion criteria. Of these, 608 and 264 were classified in the old and new system groups, respectively. The time in the waitlist was shorter (25 vs. 54 days, P < .001), with an increased frequency of HT in the new system (74% vs. 68%, P = .024). Patients who were transplanted in the new system had a longer ischemic time, increased use of temporary mechanical circulatory support and mechanical ventilation. There was no difference in posttransplant survival at 9 months (91.1% vs. 88.9%) (p = .4). We conclude that patients with RCM/HCM have benefited from the new HT allocation system, with increased access to HT without affecting short-term posttransplant survival.

Heart transplantation candidacy

PURPOSE OF REVIEW

Timely referral of eligible candidates for consideration of advanced therapies, such as a heart transplantation or mechanical circulatory support is essential. The characteristics of heart transplantation candidates have changed significantly over the years, leading to a more complex evaluation process. The present review summarizes recent advances in the evaluation process for heart transplantation eligibility.

RECENT FINDINGS

The heart transplantation allocation policy was recently reviewed in the USA in an effort to reduce waitlist mortality and to ensure fair geographic allocation of organs to the sickest patients. Moreover, patients with chronic infectious diseases, as well as malignancies, are being currently considered acceptable candidates for transplantation. Listing practices for heart transplantation vary between programmes, with a greater willingness to consider high-risk candidates at higher-volume centres.

SUMMARY

The ultimate decision to place high-risk candidates on the heart transplantation waitlist should be based on a combination of quantitative and qualitative data analysis informed by clinical judgement, and the chronic shortage of organ donors makes this process an important ethical concern for any society. Future guidelines should discuss approaches to achieve fair organ allocation while preserving improved outcomes after transplantation.

Durable Mechanical Circulatory Support in Patients With Amyloid Cardiomyopathy

Background:

Many patients with amyloid cardiomyopathy (ACM) develop advanced heart failure, and durable mechanical circulatory support (MCS) may be a consideration. However, data describing clinical outcomes after MCS in this population are limited.

Methods:

Adult patients in the Interagency Registry for Mechanically Assisted Circulatory Support with dilated cardiomyopathy (DCM, n=19 921), nonamyloid restrictive cardiomyopathy (RCM, n=248), or ACM (n=46) between 2005 and 2017 were included. Patient and device characteristics were compared between cardiomyopathy groups. The primary end point was the cumulative incidence of death with heart transplantation as a competing risk.

Results:

Patients with ACM (n=46) were older (61 years [interquartile range, 55–69 years] versus 58 years [interquartile range, 49–66 years] for DCM and 55 years [interquartile range, 46–62 years] for nonamyloid RCM, P <0.001) and were more commonly Interagency Registry for Mechanically Assisted Circulatory Support profile 1 (30.4% versus 17.9% for DCM and 21.0% for nonamyloid RCM, P =0.04) at device implantation. Use of biventricular support (biventricular assist device or total artificial heart) was the highest for patients with ACM (41.3% versus 6.7% and 19.4% for patients with DCM and nonamyloid RCM, respectively, P =0.014). The cumulative incidence of death was highest for patients with ACM relative to those with DCM or nonamyloid RCM ( P <0.001) but did not differ significantly between groups for those who required biventricular MCS.

Conclusions:

Compared with patients with DCM or nonamyloid RCM who received durable MCS, those with ACM experienced the highest use of biventricular support and the worst survival. These data highlight concerns with the use of durable MCS for patients with ACM.

Comparing outcomes for infiltrative and restrictive cardiomyopathies under the new heart transplant allocation system

The new heart transplantation (HT) allocation policy was introduced on 10/18/2018. Using the UNOS registry, we examined early outcomes following HT for restrictive cardiomyopathy, hypertrophic cardiomyopathy, cardiac sarcoidosis, or cardiac amyloidosis compared to the old system. Those listed who had an event (transplant, death, or waitlist removal) prior to 10/17/2018 were in Era 1, and those listed on or after 10/18/2018 were in Era 2. The primary endpoint was death on the waitlist or delisting due to clinical deterioration. A total of 1232 HT candidates were included, 855 (69.4%) in Era 1 and 377 (30.6%) in Era 2. In Era 2, there was a significant increase in the use of temporary mechanical circulatory support and a reduction in the primary endpoint, (20.9 events per 100 PY (Era 1) vs. 18.6 events per 100 PY (Era 2), OR 1.98, p = .005). Median waitlist time decreased (91 vs. 58 days, p < .001), and transplantation rate increased (119.0 to 204.7 transplants/100 PY for Era 1 vs Era 2). Under the new policy, there has been a decrease in waitlist time and waitlist mortality/delisting due to clinical deterioration, and an increase in transplantation rates for patients with infiltrative, hypertrophic, and restrictive cardiomyopathies without any effect on post-transplant 6-month survival.