Tenosynovial and Cardiac Transthyretin Amyloidosis in Japanese Patients Undergoing Carpal Tunnel Release

Background: Wild-type transthyretin cardiac amyloidosis (ATTRwt-CA) is a life-threatening progressive disease. Recent studies have shown that the detection of transthyretin (TTR) amyloid in tenosynovial tissue may play an important role in the diagnosis of cardiac amyloidosis. The aim of this study was to determine the prevalence of TTR amyloid deposits in surgical tissue of patients undergoing carpal tunnel surgery and to clarify the clinical significance of concomitant cardiac examination with ^{99 m}Tc-labeled pyrophosphate (^{99 m}Tc-PYP) scintigraphy in those patients with TTR deposition. Methods and Results: We evaluated 79 consecutive patients undergoing carpal tunnel release surgery and biopsy of tenosynovial tissue. The mean (±SD) age of the patients at surgery was 71.6±12.5 years (range 30-95 years); 32 patients (41%) were male. TTR amyloid deposition in tenosynovial tissue was observed in 27 patients (34%). Sixteen of those 27 patients underwent ^{99 m}Tc-PYP scintigraphy. Of those 16 patients, 3 (19%) had Grade 2 uptake on ^{99 m}Tc-PYP scintigraphy. None of the 3 patients with a diagnosis of ATTRwt-CA had apparent cardiac symptoms and left ventricular wall thickness >13 mm. Conclusions: Concomitant cardiac examination with ^{99 m}Tc-PYP scintigraphy in patients who had TTR amyloid deposition in tenosynovial tissue resulted in the identification of 19% of patients with a diagnosis of ATTRwt-CA. This diagnostic approach seems to be useful for the early diagnosis of the disease.