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Tenosynovial tissue sampling at the time of carpal tunnel surgery can help screen for early cardiac amyloidosis while it is still reversible or stoppable, researchers reported.

Of 98 patients undergoing the surgery, 10 had a positive tenosynovial biopsy for amyloid, according to Mazen Hanna, MD, of the Cleveland Clinic in Ohio, and colleagues.

"In our cohort, two of the 10 patients with biopsy-diagnosed amyloidosis were found to have AL," said Hanna and co-authors in the . "As AL is a much more rapidly progressive disease with a poor prognosis after cardiac involvement is advanced, the early recognition of this entity is even more important to initiate appropriate disease-modifying therapy."

As shown in their study, cardiac imaging subsequently led two patients to discover that they had cardiac involvement -- one in the form of light-chain amyloidosis (AL) and the other, transthyretin disease (ATTR) -- and resulted in the patients starting appropriate therapy before they developed full-blown amyloid cardiomyopathy. A third patient also started therapy because of a mutation in the TTR gene that would lead to a progressive polyneuropathy.

and are two investigational amyloidosis therapies that have received breakthrough designation from the FDA, and patisiran (Onpattro) and inotersen (Tegsedi) were recently approved for treatment of patients with polyneuropathy associated with hereditary ATTR.

'Under-recognized Etiology of HF with Preserved EF'

"We believe that the low cost of screening patients for amyloidosis at the time of carpal tunnel release surgery may avert the expense of progressive heart failure care in patients diagnosed early," Hanna and colleagues said, noting that amyloid cardiomyopathy is an "under-recognized etiology of heart failure with preserved ejection fraction."

Writing in an , Matthew Maurer, MD, of Columbia University Medical Center in New York City, and Frederick Ruberg, MD, of Boston Medical Center, said, "It remains to be determined which screening methodology will prove the best approach, but given the emerging nature of amyloidosis, a screening algorithm will likely be incorporated into everyday clinical practice in the near future."

Participants in the prospective study consisted of 98 consecutive carpal tunnel surgery recipients, and participating sites were six surgical facilities in the Cleveland Clinic health system.

Patients with ATTR showed no difference in plasma transthyretin concentration or tetramer kinetic stability, suggesting that these measures alone cannot be used to detect disease, the researchers said.

All those with confirmed amyloid deposits in tenosynovial tissue specimens went on to get cardiac imaging.

Maurer and Ruberg noted that evaluating such a limited tissue sample for amyloidosis after surgery may explain why only 10% of patients were found to have it, and it is possible that some of the patients with negative biopsies may have had the condition as well.

It's also unclear whether there is really no link between unstable circulating transthyretin and amyloid deposition, given that the study did not adjust for a transthyretin-binding protein that is lower in ATTR amyloidosis than in matched controls, the editorial also suggested.

For their part, Hanna and colleagues said they have longer follow-up planned as the next phase of the study.