Prevalence of Transthyretin Amyloid Cardiomyopathy in Heart Failure With Preserved Ejection Fraction.

Importance: Heart failure (HF) with preserved ejection fraction (HFpEF) is common, is frequently associated with ventricular wall thickening, and has no effective therapy. Transthyretin amyloid cardiomyopathy (ATTR-CM) can cause the HFpEF clinical phenotype, has highly effective therapy, and is believed to be underrecognized. Objective: To examine the prevalence of ATTR-CM without and with systematic screening in patients with HFpEF and ventricular wall thickening. Design, Setting, and Participants: This population-based cohort study assessed ATTR-CM prevalence in 1235 consecutive patients in southeastern Minnesota with HFpEF both without (prospectively identified cohort study) and with (consenting subset of cohort study, n = 286) systematic screening. Key entry criteria included validated HF diagnosis, age of 60 years or older, ejection fraction of 40% or greater, and ventricular wall thickness of 12 mm or greater. In this community cohort of 1235 patients, 884 had no known ATTR-CM, contraindication to technetium Tc 99m pyrophosphate scanning, or other barriers to participation in the screening study. Of these 884 patients, 295 consented and 286 underwent scanning between October 5, 2017, and March 9, 2020 (community screening cohort). Exposures: Medical record review or technetium Tc 99m pyrophosphate scintigraphy and reflex testing for ATTR-CM diagnosis. Main Outcomes and Measures: The ATTR-CM prevalence by strategy (clinical diagnosis or systematic screening), age, and sex. Results: A total of 1235 patients participated in the study, including a community cohort (median age, 80 years; interquartile range, 72-87 years; 630 [51%] male) and a community screening cohort (n = 286; median age, 78 years; interquartile range, 71-84 years; 149 [52%] male). In the 1235 patients in the community cohort without screening group, 16 patients (1.3%; 95% CI, 0.7%-2.1%) had clinically recognized ATTR-CM. The prevalence was 2.5% (95% CI, 1.4%-4.0%) in men and 0% (95% CI, 0.0%-0.6%) in women. In the 286 patients in the community screening cohort, 18 patients (6.3%; 95% CI, 3.8%-9.8%) had ATTR-CM. Prevalence increased with age from 0% in patients 60 to 69 years of age to 21% in patients 90 years and older (P < .001). Adjusting for age, ATTR-CM prevalence differed by sex, with 15 of 149 men (10.1%; 95% CI, 5.7%-16.1%) and 3 of 137 women (2.2%; 95% CI, 0.4%-6.3%) having ATTR-CM (P = .002). Conclusions and Relevance: In this cohort study based in a community-based setting, ATTR-CM was present in a substantial number of cases of HFpEF with ventricular wall thickening, particularly in older men. These results suggest that systematic evaluation can increase the diagnosis of ATTR-CM, thereby providing therapeutically relevant phenotyping of HFpEF.

A Proteomic Atlas of Cardiac Amyloid Plaques.

BACKGROUND: In vivo mechanisms of amyloid clearance and cardiac tissue damage in cardiac amyloidosis are not well understood. OBJECTIVES: We aimed to define and quantify the amyloid plaque proteome in cardiac transthyretin amyloidosis (ATTR) and light chain amyloidosis (AL) and identify associations with patient characteristics and outcomes. METHODS: A proteomics approach was used to identify all proteins in cardiac amyloid plaques, and to compare both normal and diseased controls. All proteins identified within amyloid plaques were defined as the expanded proteome; only proteins that were enriched in comparison to normal and disease controls were defined as the amyloid-specific proteome. RESULTS: Proteomic data from 292 patients with ATTR and 139 patients with AL cardiac amyloidosis were included; 160 and 161 unique proteins were identified in the expanded proteomes, respectively. In the amyloid-specific proteomes, we identified 28 proteins in ATTR, 19 in AL amyloidosis, with 13 proteins overlapping between ATTR and AL. ATTR was characterized by a higher abundance of complement and contractile proteins and AL by a higher abundance of keratins. We found that the proteome of kappa AL had higher levels of clusterin, a protective chaperone, and lower levels of light chains than lambda despite higher levels of circulating light chains. Hierarchical clustering identified a group of patients with worse survival in ATTR, characterized by high levels of PIK3C3, a protein with a central role in autophagy. CONCLUSIONS: Cardiac AL and ATTR have both common and distinct pathogenetic mechanisms of tissue damage. Our findings suggest that autophagy represents a pathway that may be impaired in ATTR and should be further studied.

Amyloidosis in surgically resected atrial appendages: a study of 345 consecutive cases with clinical implications.

Histomorphologic parameters of atrial appendages removed during the Cox-Maze procedure have been shown to correlate with recurrence of atrial fibrillation. While amyloid deposition has been noted within atrial appendages, the incidence and significance remains incompletely understood. More accurate amyloid typing methodologies and targeted pharmacotherapeutics have recently been developed, prompting pathologists to provide more detailed information about the type of amyloid identified in such samples. This study sought to fully characterize the morphologic characteristics of atrial amyloid as well as its incidence and clinical significance. Tissue archives were queried for atrial appendages removed during the cardiac surgeries (2010-2014). Patient demographics, imaging features, and salient clinical findings were recorded. Pattern and extent of amyloid deposition were recorded. Typing of the amyloid protein, when present, was performed on a subset of cases by laser capture microdissection with mass spectrometry-based proteomic analysis. A total of 383 atrial appendages from 345 consecutive patients were included in the study (mean age, 69 years; range, 26-92 years). Amyloid was present in 46% of patients. A linear relationship was observed between age and presence of atrial amyloidosis. Women were more likely to have atrial amyloidosis. Two distinct morphologies of amyloid were observed: filamentous and nonfilamentous, and correlated perfectly with amyloid type (filamentous = AANF-type amyloid; nonfilamentous = ATTR-type amyloid). Filamentous deposits were observed in 91% of those with amyloid. Amyloid was more likely to be found in the left atrial appendage than the right. Patients with atrial amyloid, irrespective of type, were more likely to have experienced stroke or TIA and more likely to have atrial arrhythmia preoperatively. Postoperatively, those with atrial amyloid are more likely to experience recurrence of arrhythmia than those who did not have atrial amyloid. Understanding the morphologic characteristics of AANF-type amyloid will allow for identification by the light microscopy and obviates the need for expensive ancillary typing techniques. The finding of nonfilamentous amyloid, should still prompt confirmation of amyloid type so that targeted therapy may be employed.

Global Pulmonary Vascular Remodeling in Pulmonary Hypertension Associated With Heart Failure and Preserved or Reduced Ejection Fraction.

BACKGROUND: We hypothesized that pulmonary venous hypertension in heart failure (HF) leads to predominate remodeling of pulmonary veins and that the severity of venous remodeling is associated with the severity of pulmonary hypertension (PH) in HF. METHODS: Patients with HF (n=108; 53 preserved and 55 reduced ejection fraction) with PH (HF-PH; pulmonary artery systolic pressure [PASP] ≥40 mm Hg) were compared to normal controls (n=12) and patients with primary pulmonary veno-occlusive disease (PVOD; n=17). In lung specimens from autopsy (control, HF-PH, and 7 PVOD) or surgery (10 PVOD), quantitative histomorphometry was performed in all analyzable arteries (n=4949), veins (n=7630), and small indeterminate vessels (IV; n=2168) to define percent medial thickness (arteries) and percent intimal thickness (%IT) (arteries, veins, and IV) relative to external diameter. RESULTS: The average arterial percent medial thickness (control, 6.9; HF-PH, 11.0; PVOD, 15.0), arterial %IT (control, 4.9; HF-PH, 14.9; PVOD, 31.1), venous %IT (control, 14.0; HF-PH, 24.9; PVOD, 43.9), and IV %IT (control, 10.6; HF-PH, 25.8; PVOD, 50.0) in HF-PH were higher than controls (P<0.0001 for all) but lower than PVOD (P≤0.005 for all). PASP (mm Hg) was lower in HF-PH (median, 59 [interquartile range, 50-70]) than in PVOD (median, 91 [interquartile range, 82-103]). PASP correlated with arterial percent medial thickness (r=0.41) and arterial %IT (r=0.35) but more strongly with venous %IT (r=0.49) and IV %IT (r=0.55) (P<0.0001 for all). Associations between PASP and venous or IV %IT remained significant after adjusting for arterial percent medial thickness and %IT and did not vary by HF type. In patients with right heart catheterization (30 HF-PH, 14 PVOD), similar associations between the transpulmonary gradient and pulmonary vascular remodeling existed, with numerically stronger associations for venous and IV %IT. Although the PASP was slightly higher in patients with HF-PH with right ventricular dysfunction, pulmonary vascular remodeling was not more severe. Pulmonary vascular remodeling severity was associated with reductions in the diffusing capacity of the lungs. CONCLUSIONS: In HF, PH is associated with global pulmonary vascular remodeling, but the severity of PH correlates most strongly with venous and small IV intimal thickening, similar to the pattern observed in PVOD. These findings expand our understanding of the pathobiology of PH in HF.

FOXO3a regulates BNIP3 and modulates mitochondrial calcium, dynamics, and function in cardiac stress.

The forkhead box O3a (FOXO3a) transcription factor has been shown to regulate glucose metabolism, muscle atrophy, and cell death in postmitotic cells. Its role in regulation of mitochondrial and myocardial function is not well studied. Based on previous work, we hypothesized that FOXO3a, through BCL2/adenovirus E1B 19-kDa protein-interacting protein 3 (BNIP3), modulates mitochondrial morphology and function in heart failure (HF). We modulated the FOXO3a-BNIP3 pathway in normal and phenylephrine (PE)-stressed adult cardiomyocytes (ACM) in vitro and developed a cardiotropic adeno-associated virus serotype 9 encoding dominant-negative FOXO3a (AAV9.dn-FX3a) for gene delivery in a rat model of HF with preserved ejection fraction (HFpEF). We found that FOXO3a upregulates BNIP3 expression in normal and PE-stressed ACM, with subsequent increases in mitochondrial Ca2+, leading to decreased mitochondrial membrane potential, mitochondrial fragmentation, and apoptosis. Whereas dn-FX3a attenuated the increase in BNIP3 expression and its consequences in PE-stressed ACM, AAV9.dn-FX3a delivery in an experimental model of HFpEF decreased BNIP3 expression, reversed adverse left ventricular remodeling, and improved left ventricular systolic and, particularly, diastolic function, with improvements in mitochondrial structure and function. Moreover, AAV9.dn-FX3a restored phospholamban phosphorylation at S16 and enhanced dynamin-related protein 1 phosphorylation at S637. Furthermore, FOXO3a upregulates maladaptive genes involved in mitochondrial apoptosis, autophagy, and cardiac atrophy. We conclude that FOXO3a activation in cardiac stress is maladaptive, in that it modulates Ca2+ cycling, Ca2+ homeostasis, and mitochondrial dynamics and function. Our results suggest an important role of FOXO3a in HF, making it an attractive potential therapeutic target.

Correlation of histomorphological pattern of cardiac amyloid deposition with amyloid type: a histological and proteomic analysis of 108 cases.

AIMS: Prognostication and treatment selection for cardiac amyloidosis requires accurate amyloid typing. The aim of this study was to investigate the utility of histomorphology for predicting type. METHODS AND RESULTS: Autopsy cases with cardiac amyloidosis (1998-2010) were typed by the use of mass spectrometry-based proteomics. Deposition patterns were correlated with amyloid type. Among 108 decedents (mean age 75 years; 69% men), 107 had a single type, including transthyretin (ATTR) (60 cases), amyloid light chain (AL) (32 λ; 12 κ), amyloid A (AA) (two), and apolipoprotein AIV (AApoAIV) (one). Interstitial deposition was more extensive in AL amyloidosis cases than in ATTR cases [odds ratio (OR) 6.8, P = 0.0004]. Histomorphological patterns of interstitial deposition were mixed in 61% of AL amyloidosis cases and in 61% of ATTR cases, but diffuse pericellular deposits favoured AL amyloidosis (OR 10.7, P = 0.0001), nodular deposits favoured ATTR (OR 3.1, P = 0.0229), and discrete pericellular deposits tended to partially favour ATTR (OR 1.7, P = 0.1970). Arterial and venous deposits each favoured AL amyloidosis (OR ranging from 9.3 to 192.0, P-value ranging from 0.0022 to <0.0001), and were severe in AL amyloidosis. Endocardial deposits favoured AL amyloidosis (OR 46.3, P < 0.0001) and were also more severe in AL amyloidosis. CONCLUSIONS: The extent and distribution of cardiac amyloidosis strongly correlate with amyloid type, suggesting fundamental differences in the pathobiology of deposition. The tendency for mixed patterns to occur limits the practicality and accuracy of using histopathology for amyloid typing.