Deep phenotyping of p.(V142I)-associated variant transthyretin amyloid cardiomyopathy: Distinct from wild-type transthyretin amyloidosis?

AIMS

Transthyretin amyloid cardiomyopathy (ATTR-CM) is an increasingly recognized cause of heart failure. A total of 3-4% of individuals of African descent carry a TTR gene mutation encoding the p.(V142I) variant, a powerful risk factor for development of variant ATTR-CM (ATTRv-CM); this equates to 1.6 million carriers in the United States. We undertook deep phenotyping of p.(V142I)-ATTRv-CM and comparison with wild-type ATTR-CM (ATTRwt-CM).

METHODS AND RESULTS

A retrospective study of 413 patients with p.(V142I) ATTRv-CM who attended the UK National Amyloidosis Centre (NAC) was conducted. Patients underwent evaluation at time of diagnosis, including clinical, echocardiography, and biomarker analysis; a subgroup had cardiac magnetic resonance (CMR) imaging. A total of 413 patients with ATTRwt-CM, matched for independent predictors of prognosis (age, NAC Stage, decade of first presentation), were used as a comparator group. At time of diagnosis, patients with ATTRv-CM had significant functional impairment by New York Heart Association classification (NHYA class ≥ III; 38%) and 6-min walk test distance (median 276 m). Median 5-year survival in ATTRv-CM patients was 31 versus 59 months in matched patients with ATTRwt-CM (p < 0.001). Patients with ATTRv-CM had significant impairment of functional parameters by echocardiography including biventricular impairment, high burden of regurgitant valvular disease and low cardiac output. Multivariable analysis revealed the prognostic importance of right ventricular dysfunction. CMR and histological analysis revealed myocyte atrophy and widespread myocardial infiltration in ATTRv-CM.

CONCLUSION

p.(V142I)-ATTRv-CM has an aggressive phenotype characterized by myocyte loss and widespread myocardial infiltration which may account for frequent biventricular failure and poor prognosis in this ATTR-CM genotypic subgroup.

172 CLINICAL AND PROGNOSTIC IMPLICATIONS OF RV UPTAKE WITH RADIONUCLIDE SCINTIGRAPHY IN TRANSTHYRETIN CARDIAC AMYLOIDOSIS

Aims

The prognostic role of bone tracer uptake in transthyretin cardiac amyloidosis (ATTR-CA) is controversial. The study investigated the potential prognostic significance of biventricular (BiV) uptake in ATTR-CA.

Methods

Consecutive ATTR-CA patients who had cardiac scintigraphy with acquisition of planar and single-photon emission computed tomography (SPECT) images from the National Amyloidosis Centre (NAC) and four Italian centres were included. Planar BiV uptake was defined in presence of right ventricle (RV) uptake and graded in combination with SPECT imaging. The primary outcome was all-cause mortality.

Results

Among 1422 patients with ATTR-CA, BiV uptake was found in 85% of cases on planar scintigraphy and in 100% of cases on SPECT images. During a median follow-up of 39 months, BiV uptake at planar scintigraphy was associated with a higher all-cause mortality compared to isolated LV uptake (40.5% vs 10.7%, p&lt;0.001), whereas the Perugini scale was not (p=0.27 in grade 2 vs 3). At multivariable analysis, RV uptake at planar scintigraphy leading to BiV uptake (HR 2.80, p=0.001), together with higher age at diagnosis (HR 1.03, p=0.001), V122I TTR variant (HR 1.60, p=0.001), NAC ATTR Stage (HR 1.29, p=0.003), E/e’ (HR 1.02, p=0.044), right atrium area index (HR 1.04, p=0.018) and GLS (HR 1.05, p=0.003) were independently associated with all-cause death. At time-dependent ROC curve analysis, the addition of planar BiV uptake to the NAC stage resulted in improved accuracy of the model for prediction of all-cause death (from AUC 0.74 to 0.79; p&lt;0.001).

Conclusions

Planar RV uptake leading to BiV uptake identified ATTR-CA patients with worse outcome, potentially serving as a novel prognostic marker.

99mTc-DPD scintigraphy in immunoglobulin light chain (AL) cardiac amyloidosis

Aims

Technetium-99m-labelled 3,3-diphosphono-1,2-propanodicarboxylic acid (^99mTc-DPD scintigraphy) is recognized as highly accurate for the non-invasive diagnosis of transthyretin (ATTR) cardiac amyloidosis (CA). A proportion of patients with immunoglobulin light chain (AL) CA have also been reported to show cardiac ^99mTc-DPD uptake. Herein, we assessed the frequency and degree of cardiac ^99mTc-DPD uptake and its clinical significance among patients with AL CA.

Methods and results

Between 2010 and 2017, 292 consecutive patients with AL CA underwent ^99mTc-DPD scintigraphy and were included in this study: 114 (39%) had cardiac ^99mTc-DPD uptake: grade 1 in 75%, grade 2 in 17%, and grade 3 in 8% of cases. Patients with cardiac ^99mTc-DPD uptake had poorer cardiac systolic function and higher N-terminal pro-brain natriuretic peptide. No differences were noted in cardiac magnetic resonance parameters between patients with and without cardiac ^99mTc-DPD uptake (N = 19 and 42, respectively). Patients with cardiac ^99mTc-DPD uptake showed a trend to worse survival than those with no uptake (log-rank P = 0.056). Among 22 patients who underwent serial ^99mTc-DPD scintigraphy, 5 (23%) showed reduction in the grade of cardiac uptake.

Conclusions

In this large cohort of patients with AL CA, ^99mTc-DPD scintigraphy ∼40% of cases showed cardiac uptake, including grade 2–3 in 10% of all patients (25% of those with cardiac ^99mTc-DPD uptake). Cardiac ^99mTc-DPD uptake was associated with poorer cardiac function and outcomes. These data highlight the critical importance of ruling out AL amyloidosis in all patients with cardiac ^99mTc-DPD uptake to ensure such patients are not assumed to have ATTR CA.

Regression of cardiac amyloid deposits with novel therapeutics: reaching new frontiers in cardiac ATTR amyloidosis

Background

Cardiac involvement is the main driver of outcome in ATTR amyloidosis. Advances in therapeutics hold potential in transforming the course of the disease but the impact on cardiac amyloid load is unknown. The aim of this study was to evaluate the impact of patisiran, a new double stranded RNA based gene silencing therapy and a stabilizer, diflunisal, on cardiac amyloid load as measured by CMR and T1 mapping, in patients with ATTR amyloidosis.

Methods and results

Thirty-two patients with hereditary cardiac amyloidosis were studied. Sixteen patients received treatment with patisiran, and sixteen control subjects did not receive any disease modifying treatment. Patients were assessed with echocardiogram, CMR, NT-proBNP and six-minute walk time measurements at baseline and at 1 year (Mean interval 11.45±3.08 months in treatment group, mean interval 12.82±5.06 months in the control group). CMR analysis comprised LV volumes, T1 mapping to measure the extracellular volume (ECV) occupied by amyloid, T2 mapping and late gadolinium enhancement imaging. At 1-year follow-up, there was a substantial reduction in cardiac amyloid burden, in keeping with cardiac amyloid regression in 45% of patients on treatment. Overall the treatment group showed a reduction in ECV at 1 year follow up compared to an increase in ECV at 1 year in the control group (−1.37%, 95% CI: −3.43 to 0.68% versus 5.02%, 95% CI: 2.86% to 7.18% respectively, p&lt;0.001). The treatment group also showed an improvement in change in 6MWT at 1 year follow up compared to 6MWT at 1 year in the control group (−8.12 meters, 95% CI: −50.8 to 34.6 meters in the treatment group versus −132.27 meters, 95% CI: −216 to −48.6 meters in the control group, p=0.002). The treatment group showed a reduction in BNP at 1 year follow up compared to an increase in the control group (−567.87, 95% CI: −1288.90 to 153.15 in the treatment group versus 2004, 95% CI: 12.82 to 3995.45 in the control group, p&lt;0.001). There was no significant difference from baseline and 1-year data between the control and treatment groups for the difference in echocardiographic parameters, native T1, T2. There was a significant reduction in the percentage of injected dose by 99Tc-DPD scintigraphy in treated patients at 1 year compared to baseline.

Conclusions

These findings provide the first compelling evidence of substantial cardiac amyloid regression in ATTR amyloidosis, as well as the potential for CMR to be used to track response in treated patients with ATTR cardiac amyloidosis. Combination therapy with transthyretin knock down and stabilizing agents may well be synergistic given enhanced stoichiometry of stabilizers in the face of much reduced plasma transthyretin concentration.

Funding Acknowledgement

Type of funding source: None

Echocardiographic phenotype and prognosis in transthyretin cardiac amyloidosis

Aims

Transthyretin amyloidosis cardiomyopathy (ATTR-CM) is an increasingly recognized cause of heart failure. We sought to characterize the structural and functional echocardiographic phenotype across the spectrum of wild-type (wtATTR-CM) and hereditary (hATTR-CM) transthyretin cardiomyopathy and the echocardiographic features predicting prognosis.

Methods and results

We studied 1240 patients with ATTR-CM who underwent prospective protocolized evaluations comprising full echocardiographic assessment and survival between 2000 and 2019, comprising 766 with wtATTR-CM and 474 with hATTR-CM, of whom 314 had the V122I variant and 127 the T60A variant. At diagnosis, patients with V122I-hATTR-CM had the most severe degree of systolic and diastolic dysfunction across all echocardiographic parameters and patients with T60AhATTR-CM the least; patients with wtATTR-CM had intermediate features. Stroke volume index, right atrial area index, longitudinal strain, and E/e’ were all independently associated with mortality (P &lt; 0.05 for all). Severe aortic stenosis (AS) was also independently associated with prognosis, conferring a significantly shorter survival (median survival 22 vs. 53 months, P = 0.001).

Conclusion

The three distinct genotypes present with varying degrees of severity. Echocardiography indicates a complex pathophysiology in which both systolic and diastolic function are independently associated with mortality. The presence of severe AS was independently associated with significantly reduced patient survival.

Transthyretin V122I amyloidosis with clinical and histological evidence of amyloid neuropathy and myopathy

Hereditary transthyretin amyloidosis (ATTR) is a genetically and clinically heterogeneous disease manifesting with predominant peripheral and autonomic neuropathy; cardiomyopathy, or both. ATTR V122I is the most common variant associated with non-neuropathic familial amyloid cardiomyopathy. We present an unusual case of V122I amyloidosis with features of amyloid neuropathy and myopathy, supported by histological confirmation in both sites and diffuse tracer uptake on (99m)Tc-3,3-Diphosphono-1,2-Propanodicarboxylic acid (DPD) scintigraphy throughout skeletal and cardiac muscle. A 64 year old Jamaican man presented with cardiac failure. Cardiac MR revealed infiltrative cardiomyopathy; abdominal fat aspirate confirmed the presence of amyloid, and he was homozygous for the V122I variant of transthyretin. He also described general weakness and EMG demonstrated myopathic features. Sural nerve and vastus lateralis biopsy showed TTR amyloid. The patient is being treated with diflunisal, an oral TTR stabilising agent. Symptomatic myopathy and neuropathy with confirmation of tissue amyloid deposition has not previously been described. Extracardiac amyloidosis has implications for diagnosis and treatment.

Asthma experience in an occupational and environmental medicine clinic. Low-dose reactive airways dysfunction syndrome

The etiology of adult-onset asthma is incompletely understood. High-intensity exposure to irritants is one accepted risk factor and such cases are termed Reactive Airways Dysfunction Syndrome. The contribution to asthma of less intense and less acute exposure to irritants remains to be clarified. We report on 10 cases of nonsensitization adult-onset asthma in settings of exposure to noticeable but distinctly "tolerable" levels of inhalation irritants. This series of 10 cases represent 31% of verified asthma cases seen in our environmental and occupational medicine referral clinic over a 5-year period. We believe further exploration of this phenomenon of low dose Reactive Airways Dysfunction Syndrome is warranted.