How Imaging Scans and BNP Levels Correlate in Transthyretin Cardiac Amyloidosis

What the researchers found

Positive 99mTc-PYP grading was significantly associated with increased left ventricular mass (β=111.21, p=0.009) and greater interventricular septal thickness (β=0.48, p=0.003) in hereditary ATTR patients. Nuclear scan positivity also correlated with log-transformed BNP (β=1.99, p=0.002) in hereditary patients and log-transformed troponin (β=1.68, p=0.007) in wild-type ATTR patients.

The quantitative heart-to-contralateral lung ratio from nuclear imaging did not correlate with BNP or troponin but was significantly associated with LV mass (β=134.52, p=0.001) and septal thickness (β=0.46, p=0.002) in hereditary patients. These genotype-dependent differences support a stratified diagnostic approach.

Why it matters

Transthyretin amyloidosis is increasingly recognized as an underdiagnosed cause of heart failure, especially in elderly men. Understanding how different diagnostic tools relate to each other helps clinicians interpret results more accurately, monitor disease progression, and potentially guide treatment decisions — particularly with emerging therapies like tafamidis that can stabilize transthyretin.

How the study worked

Single-center retrospective cohort study of 183 patients aged 18+ diagnosed with transthyretin cardiac amyloidosis at Toronto General Hospital between October 2012 and December 2022. Linear regression and multivariate proportional hazard models examined associations between 99mTc-PYP scintigraphy findings, echocardiographic parameters, and cardiac biomarkers (troponin I and BNP).

What this study cannot tell us

This is a single-center retrospective study, which may limit generalizability. The sample size of 183, while reasonable for this rare condition, limits the power of subgroup analyses by genotype. The study period (2012-2022) spans a time of evolving diagnostic criteria and awareness, which could introduce bias. Longitudinal associations and prognostic value of the identified correlations were not the primary focus.

How to read the evidence

This is a single-center retrospective cohort study with 183 patients and multivariate regression analysis. While it provides useful clinical correlations, the retrospective design and single-center setting limit the evidence strength.

When this study was published

Published in 2025 using data from 2012-2022, this study reflects a decade of clinical experience at a major cardiac center during a period of rapidly evolving understanding of transthyretin amyloidosis.

The bigger picture

As transthyretin amyloidosis gains recognition and new treatments emerge, understanding the relationships between diagnostic modalities becomes essential for clinical decision-making. This study supports a move toward genotype-stratified diagnosis, where hereditary and wild-type ATTR patients may be monitored differently. The BNP findings are particularly relevant as BNP is widely used for heart failure monitoring.

Questions still open

• Could serial BNP or troponin measurements track treatment response in patients receiving tafamidis or other ATTR therapies?
• Why do the biomarker correlations differ between hereditary and wild-type ATTR — does the amyloid composition differ?
• Would adding cardiac MRI to the diagnostic approach provide additional prognostic information beyond nuclear imaging and biomarkers?

Common questions

Read the original research

Elucidating associations between technetium pyrophosphate scintigraphy, echocardiography and cardiac biomarkers in transthyretin cardiac amyloidosis.

Open heart, 12(2)

Citation

Di Giovanni, Bennett; Gustafson, Dakota; Arivalagan, Priya; Adamson, Mitchell B; Vishram-Nielsen, Julie; Delgado, Diego. (2025). Elucidating associations between technetium pyrophosphate scintigraphy, echocardiography and cardiac biomarkers in transthyretin cardiac amyloidosis.. Open heart, 12(2). https://doi.org/10.1136/openhrt-2024-002686