Screening for Cardiac Amyloidosis 5 to 15 Years After Surgery for Bilateral Carpal Tunnel Syndrome

BACKGROUND: Bilateral carpal tunnel syndrome (CTS) is a common extracardiac manifestation of amyloidosis and usually predates overt cardiac amyloidosis (CA) by several years. Screening studies on patients undergoing CTS surgery have shown a low yield of CA (2.0%), but high prevalence of amyloid in the carpal ligament. The proportion of patients with amyloid in the carpal ligament who later develop CA is unknown.

OBJECTIVES: The authors sought to investigate the prevalence of undiagnosed CA 5 to 15 years after surgery for bilateral CTS.

METHODS: Using national registries, the authors identified subjects aged 60 to 85 years with prior CTS surgery, where the first procedure on the second wrist was performed 5 to 15 years earlier. Invitations to participate in the study were sent by mail. Per international recommendations, the initial cardiac evaluation included echocardiography, 99mtechnetium-pyrophosphate scintigraphy, and assessment of monoclonal proteins in serum and urine.

RESULTS: A total of 250 subjects (35.7% of those invited) participated in the study. The median age was 70.4 years, and 50% were female. CA was diagnosed in 12 patients (4.8%; 95% CI: 2.5%-8.2%), and all cases were wild-type transthyretin amyloidosis (ATTRwt). The prevalence of ATTRwt in men was 8.8% (95% CI: 4.5%-15.2%; n = 11), and 21.2% (95% CI: 11.1%-34.7%) in male subjects ≥70 years with a BMI <30 kg/m2. All but 2 patients diagnosed with ATTRwt were in the lowest disease severity score (Mayo score).

CONCLUSIONS: Screening for CA in patients with prior surgery for bilateral CTS finds approximately 5% with early-stage transthyretin CA. The clinical yield was higher (>1 in 5) when focusing on nonobese men ≥70 years, showing potential for systematic screening.