Progression of myocardial sympathetic denervation assessed by 123I-MIBG imaging in familial amyloid polyneuropathy and the effect of liver transplantation

Diagnostic and prognostic contribution of DPD scintigraphy in transthyretin V30M cardiac amyloidosis

BACKGROUND

Early diagnosis and prognostic stratification of cardiac transthyretin amyloidosis are crucial. Although 99mTc 3,3-diphosphono-1,2-propanedicarboxylic acid (DPD) scintigraphy is the preferred method for the non-invasive diagnosis, its accuracy appears to be limited in transthyretin amyloidosis protein (ATTR) V30M mutation. Furthermore, its prognostic value in this mutation is unknown. This study investigated the diagnostic value of DPD scintigraphy to detect ATTR cardiomyopathy in V30M mutation and explored its prognostic value regarding mortality.

METHODS

A total of 288 ATTR V30M mutation carriers (median age: 46 years; 49% males) without myocardial thickening (defined as septal thickness ≥13mm) attributable to other causes and who underwent DPD scintigraphy were enrolled. ATTR cardiomyopathy was defined by septal thickness ≥13mm and at least one of the criteria: late heart-to-mediastinum (H/M) 123I-metaiodobenzylguanidine (MIBG) uptake ratio <1.60; electrical heart disease or biopsy-documented amyloidosis.

RESULTS

ATTR cardiomyopathy was identified in 41 (14.2%) patients and cardiac DPD uptake in 34 (11.8%). During a mean follow-up of 33.6 ± 1.2 months, 16 patients died (5.6%). Mortality was 14 times higher in patients with ATTR cardiomyopathy, 13 times higher in those with DPD uptake and 10 times higher in those with late H/M MIBG <1.60. The combined assessment of septal thickness and cardiac DPD uptake improved risk stratification: patients without septal thickening and without DPD retention had an excellent prognosis while those who presented either or both of them had a significantly worse prognosis, with 5-year mortality rates ranging from 39.9 to 53.3%.

CONCLUSIONS

DPD scintigraphy is useful for prognostic stratification of ATTR V30M mutation carriers. Patients without septal thickening and no DPD uptake present the best prognosis compared to those with any signs of cardiac involvement.

Expert opinion on monitoring symptomatic hereditary transthyretin-mediated amyloidosis and assessment of disease progression

BACKGROUND

Hereditary transthyretin-mediated amyloidosis, also known as ATTRv amyloidosis (v for variant), is a rare, autosomal dominant, fatal disease, in which systemic amyloid progressively impairs multiple organs, leading to disability and death. The recent approval of disease-modifying therapies offers the hope of stabilization or eventual reversal of disease progression, and yet highlights a lack of disease-management guidance. A multidisciplinary panel of expert clinicians from France and the US came to consensus on monitoring the disease and identifying progression through a clinical opinion questionnaire, a roundtable meeting, and multiple rounds of feedback.

MONITORING DISEASE AND PROGRESSION

A multidisciplinary team should monitor ATTRv amyloidosis disease course by assessing potential target organs at baseline and during follow-up for signs and symptoms of somatic and autonomic neuropathy, cardiac dysfunction and restrictive cardiomyopathy, and other manifestations. Variability in penetrance, symptoms, and course of ATTRv amyloidosis requires that all patients, regardless of variant status, undergo regular and standardized assessment in all these categories. Progression in ATTRv amyloidosis may be indicated by: worsening of several existing quantifiable symptoms or signs; the appearance of a new symptom; or the worsening of a single symptom that results in a meaningful functional impairment.

CONCLUSIONS

We suggest that a multisystem approach to monitoring the signs and symptoms of ATTRv amyloidosis best captures the course of the disease. We hope this work will help form the basis of further, consensus-based guidance for the treatment of ATTRv amyloidosis.

Multimodality Imaging in the Evaluation and Management of Cardiac Amyloidosis

Systemic amyloidosis is a heterogeneous group of disorders where misfolded proteins deposit in the various organs as nonbranching fibrils with a β-pleated-sheet structure called amyloid. Extensive extracellular deposition of these amyloid fibrils eventually leads to organ dysfunction. Involvement of the heart, termed as cardiac amyloidosis, leads to heart failure if left untreated and carries high morbidity and mortality. Current interest in cardiac amyloidosis is growing rapidly thanks to the recent development of effective targeted treatment options, driving the need for better and earlier detection of the condition, which is largely underdiagnosed and far commoner than recognized. Timely diagnosis of cardiac amyloidosis is challenging, but is poised to improve with emergence of newer noninvasive imaging techniques, potentially obviating the need for endomyocardial biopsy in some patients and providing prognostic information. With recent advances in the therapeutic options for cardiac amyloidosis, an area of immense interest is the adoption of imaging as biomarkers for longitudinal assessment of disease progression and treatment response. In this article, we provide an overview of cardiac amyloidosis, discuss the role of imaging modalities in cardiac amyloidosis, and explore future directions for imaging in cardiac amyloidosis.

Orthostatic hypotension in hereditary transthyretin amyloidosis: epidemiology, diagnosis and management

Purpose

Neurogenic orthostatic hypotension is a prominent and disabling manifestation of autonomic dysfunction in patients with hereditary transthyretin (TTR) amyloidosis affecting an estimated 40–60% of patients, and reducing their quality of life. We reviewed the epidemiology and pathophysiology of neurogenic orthostatic hypotension in patients with hereditary TTR amyloidosis, summarize non-pharmacologic and pharmacological treatment strategies and discuss the impact of novel disease-modifying treatments such as transthyretin stabilizers (diflunisal, tafamidis) and RNA interference agents (patisiran, inotersen).

Methods

Literature review.

Results

Orthostatic hypotension in patients with hereditary transthyretin amyloidosis can be a consequence of heart failure due to amyloid cardiomyopathy or volume depletion due to diarrhea or drug effects. When none of these circumstances are apparent, orthostatic hypotension is usually neurogenic, i.e., caused by impaired norepinephrine release from sympathetic postganglionic neurons, because of neuronal amyloid fibril deposition.

Conclusions

When recognized, neurogenic orthostatic hypotension can be treated. Discontinuation of potentially aggravating medications, patient education and non-pharmacologic approaches should be applied first. Droxidopa (Northera^®), a synthetic norepinephrine precursor, has shown efficacy in controlled trials of neurogenic orthostatic hypotension in patients with hereditary TTR amyloidosis and is now approved in the US and Asia. Although they may be useful to ameliorate autonomic dysfunction in hereditary TTR amyloidosis, the impact of disease-modifying treatments on neurogenic orthostatic hypotension is still uninvestigated.

Pacemaker implantation in familial amyloid polyneuropathy: when and for whom?

BACKGROUND

Despite the important role of cardiac pacing in preventing syncope and sudden cardiac death in familial amyloid polyneuropathy (FAP), we lack clear guidelines as to the ideal timing and indications for permanent pacemaker implantation.

PURPOSE

The purpose of this study was to evaluate the ideal timing for pacemaker implantation in FAP patients submitted to liver transplantation.

METHODS

Retrospective study of 258 FAP patients submitted to liver transplantation between 1992 and 2012. Comparison of three groups: (A) patients without pacemaker (N = 122); (B) patients submitted to pacemaker implantation after liver transplantation, with documented conduction disorders (N = 73); and (C) patients submitted to "prophylactic" pacemaker implantation before transplantation, (N = 73). Patients were followed up for 12.2 ± 6.7 years.

RESULTS

The majority of patients (57%) were referred for pacemaker implantation, which occurred before liver transplantation in 50% of cases. Patients who required pacemaker after transplantation presented significantly higher Machado-Joseph Score during pre-transplant evaluation than those who did not require pacemaker (24 ± 10 vs 20 ± 10, p = .025), and also exhibited higher levels of hepatic cytolysis enzymes and hyperbilirubinemia. The most common indication for permanent pacemaker was first degree atrioventricular block, with a mean time between transplantation and pacemaker implantation of 8.7 ± 4.2 years. During long-term follow-up, all-cause mortality was 27% and was lowest in the group submitted to pacemaker implantation only after liver transplantation (p = 0.002).

CONCLUSION

The majority of FAP patients submitted to liver transplantation will need a pacemaker at some time of follow-up. However, it seems that there is no benefit in "prophylactic" cardiac pacing before liver transplantation.

Imaging cardiac innervation in amyloidosis

Cardiac amyloidosis is a form of restrictive cardiomyopathy resulting in heart failure and potential risk on arrhythmia, due to amyloid infiltration of the nerve conduction system and the myocardial tissue. The prognosis in this progressive disease is poor, probably due the development of cardiac arrhythmias. Early detection of cardiac sympathetic innervation disturbances has become of major clinical interest, because its occurrence and severity limits the choice of treatment. The use of iodine-123 labelled metaiodobenzylguanidine ([I-123]MIBG), a chemical modified analogue of norepinephrine, is well established in patients with heart failure and plays an important role in evaluation of sympathetic innervation in cardiac amyloidosis. [I-123]MIBG is stored in vesicles in the sympathetic nerve terminals and is not catabolized like norepinephrine. Decreased heart-to-mediastinum ratios on late planar images and increased wash-out rates indicate cardiac sympathetic denervation and are associated with poor prognosis. Single photon emission computed tomography provides additional information and has advantages for evaluating abnormalities in regional distribution in the myocardium. [I-123]MIBG is mainly useful in patients with hereditary and wild-type ATTR cardiac amyloidosis, not in AA and AL amyloidosis. The potential role of positron emission tomography for cardiac sympathetic innervation in amyloidosis has not yet been identified.