Don't judge a book by its cover: a case report of apolipoprotein A-IV cardiac amyloidosis

Mohammed Basel Allaw, Arjun Sinha, Kambiz Ghafourian, Ryan Avery, Richard L. Weinberg, Jon W. Lomasney, Sanjiv J. Shah, Ravi B. Patel*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Background: To date, at least 20 different amyloidogenic proteins have been documented. Growing evidence suggests that despite being part of the universal amyloid proteome, apolipoprotein A-IV can be amyloidogenic, accounting for less than 1% of cases. Case summary: A 75-year-old woman was admitted for paroxysmal nocturnal dyspnoea and intermittent exertional shortness of breath and was found to be in acute heart failure. The patient underwent intravenous diuretic therapy and was discharged after decongestion. She then underwent a battery of outpatient tests to determine aetiology of her heart failure. Cardiac magnetic resonance imaging showed severe concentric left ventricular hypertrophy and diffuse late gadolinium enhancement, concerning for amyloidosis, but serologic evaluation for amyloidogenic light chain (AL) amyloidosis was negative. Tc 99m pyrophosphate (PYP) scan showed Grade 2 uptake at 1 h that was only moderately suggestive of transthyretin (TTR) amyloidosis. She ultimately received a right heart catheterization and endomyocardial biopsy, which showed apolipoprotein A-IV amyloid deposition within Congo red-positive areas of the endomyocardial specimen. The patient continues to report dyspnoea on exertion but has avoided additional heart failure admissions with intensification of her diuretic regimen. Discussion: In this case, nuclear PYP scan to evaluate for TTR amyloidosis demonstrated focal PYP uptake, but endomyocardial biopsy demonstrated apolipoprotein A-IV deposition without evidence of TTR amyloidosis. Our case increases knowledge of this rare form of amyloidosis, suggests that it may result in false positive nuclear PYP results, and highlights the importance of its evaluation, particularly in circumstances in which investigations do not reveal definitive evidence of AL or TTR amyloidosis.

Original languageEnglish (US)
Article numberytad341
JournalEuropean Heart Journal - Case Reports
Volume7
Issue number8
DOIs
StatePublished - Aug 1 2023

Funding

Funding: This work was supported by grant KL2TR001424 from the National Institutes of Health/National Center for Advancing Translational Sciences.

Keywords

  • Apolipoprotein A-IV amyloidosis
  • Cardiac amyloidosis
  • Case report
  • Restrictive cardiomyopathy

ASJC Scopus subject areas

  • Cardiology and Cardiovascular Medicine

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