Author + information
- Avinainder Singha,b,
- Hallie Gellera,b,
- Carolyn Glassa,b,
- Tara Mirtoa,b,
- Robert Paderaa,b,
- Richard Mitchella,b and
- Rodney Falka,b
Background: Light chain (AL) & transthyretin (TTR) are the most common types of cardiac amyloidosis. AL is caused by a monoclonal gammopathy, but monoclonal gammopathy of unknown significance (MGUS) can also be seen in TTR amyloidosis & may confuse the clinical picture. It is essential to correctly determine the amyloid type as therapy is entirely different. Immunohistochemistry (IHC) of endomyocardial biopsy specimens is widely used for typing amyloid deposits, but mass spectrometry (though not widely available) is deemed the gold standard. We therefore sought to evaluate the implications of circulating paraproteins & free light chains (FLC) on IHC results among patients with a clinical picture of TTR amyloidosis.
Methods: Pts. in whom both IHC and mass spectrometry had been performed were identified by record review. Most cases had equivocal IHC or a clinical picture discrepant with IHC findings
Results: 9 pts. were identified with IHC suggestive of AL amyloidosis but a clinical picture of TTR. All patients had elevated circulating FLC & the IHC results corresponded with the elevated FLC. 67% pts. also had MGUS or known plasma cell dyscrasia. 1 patient had received chemotherapy for suspected AL, prior to our evaluation.
Conclusions: IHC may show inaccurate results, especially in the setting of MGUS/elevated FLC, most likely due to interference of unrelated light chain with amyloid IHC. Mass spectrometry should be used for definitive diagnosis in cases with discordant IHC & clinical picture, or equivocal IHC.
Poster Hall, Hall C
Saturday, March 18, 2017, 9:45 a.m.-10:30 a.m.
Session Title: Advances in HCM, PPCM and Other Cardiomyopathies
Abstract Category: 13. Heart Failure and Cardiomyopathies: Clinical
Presentation Number: 1201-265
- 2017 American College of Cardiology Foundation