Microvascular dysfunction in patients with transthyretin cardiac amyloidosis evaluated by 13N-ammonia positron emission tomography–computed tomography: is it an early marker of the disease?

Q: What is the clinical evidence from this study?

Study design: Observational. Population: Hereditary transthyretin amyloidosis (ATTR) (n=40). Intervention: Cardiac amyloid involvement in pathogenic TTR mutation carriers vs. Pathogenic TTR mutation carriers without cardiac involvement. Primary outcome: Mean global coronary flow reserve (CFR) assessed by 13N-ammonia PET/CT (p=<0.001).

Aristóteles Neto; Luis Miguel da Silva; Bruno Bueno; Cristian Espinoza; Vitor Emer Rosa; Viviane Tiemi Hotta; Camila de Godoi Carneiro; Carlos E Rochitte; Vagner Madrini; Jose Soares; William Azem Chalela; Marcos Santos Lima; C. A. Buchpiguel; Edward Miller; F. Fernandes

doi:10.4274/dir.2026.263687

February 4, 2026Diagnostic and Interventional RadiologyOpen Access

Microvascular dysfunction in patients with transthyretin cardiac amyloidosis evaluated by 13N-ammonia positron emission tomography–computed tomography: is it an early marker of the disease?

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Key result

Cardiac involvement in TTR mutation carriers was associated with lower mean global coronary flow reserve on 13N-ammonia PET/CT compared to non-involvement.

Key Points

To assess coronary microvascular dysfunction using 13N-ammonia PET/CT and determine whether coronary flow reserve serves as an early marker of transthyretin cardiac amyloidosis.
Evaluated myocardial blood flow and coronary flow reserve (CFR) using 13N-ammonia PET/CT with dipyridamole stress in patients with transthyretin (TTR) gene mutations with and without cardiac involvement.
Correlated CFR measurements with biomarkers (troponin, BNP), functional status (NYHA class, 6-minute walk test), and echocardiographic indices (including LVGLS and RVGLS).
Mean global CFR was significantly lower in the cardiac involvement group (1.849 ± 0.379) than in the non-involvement group (2.952 ± 0.7; P < 0.001).
A global CFR cut-off of < 2.58 differentiated cardiac involvement with a sensitivity of 100%, specificity of 75%, and an area under the curve of 0.902 (0.80–1.0; P < 0.001).
A global CFR consistent with ischemic disease (≤ 2.5) was observed in 60% (n = 12) of patients with cardiac involvement compared to 15% (n = 3) of those without cardiac involvement.

Study Design

Type

Observational (n=40)

Multicenter

Yes

PICO

P

Population

40 adults aged ≥18 years with confirmed pathogenic TTR gene mutations (20 with cardiac involvement and 20 without), excluding wild-type TTR cardiac amyloidosis.

E

Exposure / Comparator

Cardiac amyloid involvement in pathogenic TTR mutation carriers vs Pathogenic TTR mutation carriers without cardiac involvement

O

Primary Outcome

Mean global coronary flow reserve (CFR) assessed by 13N-ammonia PET/CT, p=<0.001

Main Result

Absolute Event Rate: 1.849% vs 2.952%

p-value: p=<0.001

Limitations

Small sample size
Lack of invasive coronary artery assessment
Significant age disparity between groups
Convenience sampling which may introduce bias
Use of dipyridamole as the stress agent rather than adenosine or regadenoson

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Implication

Evaluates microvascular dysfunction as a marker of transthyretin cardiac amyloidosis, suggesting its role in diagnosis and risk assessment.

Abstract

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Cite This Study

Neto et al. (2026) conducted an observational in Hereditary transthyretin amyloidosis (ATTR) (n=40). Cardiac amyloid involvement in pathogenic TTR mutation carriers vs. Pathogenic TTR mutation carriers without cardiac involvement was evaluated on Mean global coronary flow reserve (CFR) assessed by 13N-ammonia PET/CT (p=<0.001). Cardiac involvement in TTR mutation carriers was associated with lower mean global coronary flow reserve on 13N-ammonia PET/CT compared to non-involvement.

synapsesocial.com/papers/698585bd8f7c464f23009535 https://doi.org/10.4274/dir.2026.263687

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Microvascular dysfunction in patients with transthyretin cardiac amyloidosis evaluated by 13N-ammonia positron emission tomography–computed tomography: is it an early marker of the disease?

Key Points

Study Design

PICO

Main Result

Limitations

Ask about this paper

Implication

Abstract

Discussion

Cite This Study

Microvascular dysfunction in patients with transthyretin cardiac amyloidosis evaluated by 13N-ammonia positron emission tomography–computed tomography: is it an early marker of the disease?

Key Points

Study Design

PICO

Main Result

Limitations

Ask about this paper

Implication

Abstract

Discussion

Cite This Study

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