Abstract
Abstract Background In the recent past, transthyretin cardiac amyloidosis (TTR-CA) is recognized as an important cause of heart failure with preserved ejection fraction, and diagnostic utility of 99mTc-pyrophosphate (99mTc-PYP) scintigraphy in TTR-CA has been established. However, pathological evaluation is still the basis to confirm diagnosis. Subcutaneous tissue and gastrointestinal tract biopsy are useful examinations alternative to endomyocardial biopsy. Nevertheless, the positive ratio of amyloid deposition in these organs is not fully evaluated based on recent non-invasive diagnostic criteria. Purpose Our aim was to evaluate the diagnostic sensitivity of tissue biopsy in TTR-CA patients diagnosed by 99mTc-PYP scintigraphy. Methods We retrospectively evaluated 124 consecutive TTR-CA patients [wild-type (ATTRwt): 90, hereditary (hATTR): 34] who were diagnosed by positive findings of 99mTc-PYP scintigraphy (visual score 2 or 3) between June 2002 and January 2019 at our institute. Results A total of 114 patients underwent tissue biopsy at least one organ. Amyloid was detected on Congo red staining of subcutaneous tissue (43/97: 44%), gastrointestinal tract (52/78: 67%) and heart (78/79: 99%), respectively. Among 70 patients who underwent both subcutaneous tissue and gastrointestinal tract biopsy, amyloid was detected at least one specimen in 57/70 (81%). Compared to hATTR CA patients, ATTRwt CA patients had lower positive ratio of subcutaneous tissue (81% vs. 27%) and gastrointestinal tract (73% vs. 63%) biopsy. Conclusion Non-invasive diagnostic criteria of TTR-CA had excellent sensitivity of amyloid deposition in heart. The diagnostic sensitivity of subcutaneous tissue and gastrointestinal tract biopsy was lower in ATTRwt CA compared to hATTR CA. Combination of subcutaneous tissue and gastrointestinal tract biopsy was useful for pathological confirmation of amyloid deposition without endomyocardial biopsy.
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