Wrist biopsy may aid in early detection of heart disease

Biopsies taken during surgery for carpal tunnel syndrome, a condition that affects a wrist nerve, may help with early detection of transthyretin cardiac amyloidosis (ATTR-CM), a review study found. But the researchers cautioned that biopsy results cannot, on their own, confirm the presence of heart disease.

The study, “Screening for Transthyretin Amyloidosis during Carpal Tunnel release: An opportunity for Early Diagnosis,” was published in The American Journal of Cardiology.

ATTR-CM is a heart-related form of transthyretin amyloidosis (ATTR), a group of conditions marked by the accumulation of toxic clumps of the transthyretin (TTR) protein in tissues. In people with ATTR-CM, these aggregates primarily accumulate in the heart. TTR clumps can also form in other tissues in the body, including the nerves outside the brain and spinal cord — the hallmark feature of another form of ATTR called hereditary ATTR with polyneuropathy (hATTR-PN).

Carpal tunnel syndrome, a condition in which pressure on nerves in the wrist causes tingling or numbness in the hand, often develops as an early symptom of hATTR and ATTR in general.

Standard treatment for carpal tunnel syndrome involves surgery to release pressure on nerves in the wrist. Because this symptom can be an early sign of ATTR-CM, researchers have explored whether taking a small biopsy of wrist tissue during the surgery to analyze toxic TTR clumps may aid early ATTR-CM diagnosis.

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Clumps and carpal tunnel

Two doctors in France argued that carpal tunnel biopsy can be a useful tool to help detect ATTR-CM. However, they stressed that results from these biopsies need to be interpreted appropriately.

Based on available data, the doctors noted that abnormal TTR clumps have been identified in nearly one out of every five people (19.4%) undergoing biopsy during carpal tunnel surgery.

However, about two in every 100 people (2.3%) undergoing biopsy had co-existing ATTR-CM. In other words, only a fraction of people who test positive for TTR clumps on the biopsy will actually have ATTR-CM.

Data also showed that “key predictors of biopsy positivity [for TTR clumps] include advanced age, male sex, [carpal tunnel syndrome affecting both hands], and a history of spinal stenosis or trigger finger,” the researchers wrote.

Spinal stenosis refers to the narrowing of spaces within the spine that can squeeze the spinal cord or nerves. Trigger finger is a condition in which a finger or thumb catches, pops, or locks in a bent position.

The researchers suggested that a positive biopsy test during carpal tunnel surgery may serve as a useful red flag, prompting further testing “at a stage when cardiac disease may still be absent or limited.”

“At the same time, one should not attach undue importance to a positive result from a [carpal tunnel syndrome] biopsy,” the team wrote. “While this helps to identify patients who require a structured [heart] assessment, it does not, on its own, establish a diagnosis of ATTR-CM.”

The doctors also stressed that more studies are needed to better clarify the uses of this type of biopsy in ATTR-CM. In particular, it’s still unclear whether some people who test positive on carpal tunnel biopsy but don’t have ATTR-CM at that time may be at increased risk of developing the disease later on.

“Longitudinal prospective [studies] are now needed to define the true long-term risk of progression, refine surveillance strategies, and determine the most cost-effective way to integrate biopsy-based screening into routine clinical care,” the scientists wrote.