Carpal Tunnel Syndrome (CTS) is a common condition affecting the wrist and hand, characterized by numbness, tingling, and pain. Heart failure (HF) is a serious cardiovascular condition where the heart cannot pump blood efficiently enough to meet the body’s needs. While these two conditions appear entirely separate—one neurological and orthopedic, the other cardiovascular—a growing body of medical evidence reveals a surprising connection. A shared underlying systemic disease can cause both localized wrist symptoms and a progressive decline in heart function. This link means that a seemingly routine hand problem can sometimes serve as an important early warning sign for a serious condition affecting the cardiovascular system.
The Common Culprit: Amyloid Deposits
The systemic condition responsible for linking the wrist and the heart is Transthyretin Amyloidosis (ATTR amyloidosis). This disease involves a specific protein called transthyretin, which is produced primarily by the liver and transports thyroid hormone and Vitamin A. In ATTR amyloidosis, this protein becomes unstable and misfolds into insoluble fibers called amyloid fibrils. These misfolded proteins clump together and deposit in various organs and tissues, disrupting their normal function.
There are two main types of ATTR amyloidosis. The most common form linking CTS and heart failure is wild-type ATTR (wtATTR), which is related to aging and does not involve a gene mutation. This form typically affects men over the age of 60 to 65. The other type is hereditary ATTR (hATTR), caused by a mutation in the transthyretin gene, which can present earlier in life.
Amyloid in the Heart
When ATTR amyloid deposits affect the heart, the condition is specifically called Transthyretin Amyloid Cardiomyopathy (ATTR-CM), which leads to heart failure. The amyloid fibrils infiltrate the walls of the heart muscle, causing the tissue to become abnormally thick and stiff. This stiffening primarily affects the lower pumping chambers, the ventricles, preventing them from relaxing properly between heartbeats.
The inability of the heart to relax and fill efficiently is known as restrictive cardiomyopathy, which impairs the flow of blood into the heart. Because the heart cannot take in the expected amount of blood, it struggles to pump sufficient oxygenated blood to the rest of the body. This progressive decline in function leads to the signs of heart failure, such as shortness of breath, fatigue, and swelling in the legs and abdomen. The deposits can also interfere with the heart’s electrical system, increasing the risk of arrhythmias, such as atrial fibrillation, and conduction problems.
Amyloid in the Wrist
The same misfolded transthyretin proteins that infiltrate the heart can also build up in the confined spaces of the wrist, leading to Carpal Tunnel Syndrome. The amyloid deposits accumulate in the tendons and ligaments that pass through the carpal tunnel, a narrow passageway on the palm side of the wrist. This buildup causes the tissues, including the transverse carpal ligament, to thicken and swell.
The resulting increase in pressure within the tunnel compresses the median nerve, which provides sensation to much of the hand. This nerve compression causes the symptoms characteristic of CTS, including tingling, numbness, and pain in the thumb, index, middle, and ring fingers. A specific sign pointing toward ATTR amyloidosis is the development of carpal tunnel syndrome in both wrists, known as bilateral CTS.
Diagnostic Significance of the Connection
Recognizing the connection between carpal tunnel syndrome and ATTR-CM is significant for early diagnosis and treatment of the heart condition. Studies have shown that CTS caused by ATTR amyloidosis frequently appears five to ten years before the onset of cardiac symptoms. This time lag provides a crucial window for intervention, as the systemic nature of the disease means that the amyloid is already accumulating in the heart muscle.
For patients, especially men over 60, who present with bilateral carpal tunnel syndrome or have had surgery for CTS, this is considered a medical red flag for potential ATTR-CM. During carpal tunnel release surgery, orthopedic surgeons can take a tissue sample from the affected ligament or tendon sheath to test for amyloid deposits. If amyloid is detected, the patient can be referred for further evaluation, such as specialized cardiac imaging or bone scintigraphy. Identifying ATTR-CM in its early stages is important because modern treatments can stabilize the misfolded transthyretin protein, slowing the progression of heart disease and improving prognosis.