Extracardiac Biopsy Sensitivity in Transthyretin Amyloidosis Cardiomyopathy Patients With Positive 99 mTc-Labeled Pyrophosphate Scintigraphy Findings.

BACKGROUND: The accurate sensitivity of amyloid deposition in extracardiac tissue (subcutaneous tissue and gastrointestinal tract) has not been evaluated in transthyretin amyloidosis cardiomyopathy (ATTR-CM) patients. This study aimed to evaluate the sensitivity of amyloid deposition in obtained endomyocardial and extracardiac biopsies.Methods and Results: This study retrospectively evaluated 175 consecutive ATTR-CM patients (wild-type [ATTRwt]: 134, hereditary [ATTRv]: 41) who had positive findings on 99 mTc-labeled pyrophosphate (99 mTc-PYP) scintigraphy and underwent tissue biopsy of at least one organ (subcutaneous tissue, gastrointestinal tract, and endomyocardium). Amyloid deposition was observed in the subcutaneous tissue of 57/150 patients (38%), gastrointestinal tract of 80/131 patients (61%), and endomyocardium of 108/109 patients (99%). Compared to patients with ATTRv, ATTRwt had significantly lower sensitivity in subcutaneous tissue (73% vs. 25%, P<0.01) and tended to be lower in the gastrointestinal tract (74% vs. 57%, P=0.08) biopsies. Among 124 patients who underwent both subcutaneous tissue and gastrointestinal tract biopsies, amyloid was detected in at least 1 specimen in 91 (73%) patients. The sensitivity of the combination of extracardiac biopsies was 66% and 94% in ATTRwt-CM and ATTRv-CM, respectively. Multivariate analysis reveals that ATTRv was the only significant predictor of amyloid deposition in the subcutaneous tissue. CONCLUSIONS: Subcutaneous tissue and gastrointestinal tract biopsy sensitivity are inadequate, especially in patients with ATTRwt; however, the combination of these extracardiac biopsies contributes to increased sensitivity in patients with positive 99 mTc-PYP scintigraphy findings.

Clinical characteristics, outcome, and therapeutic effect of tafamidis in wild-type transthyretin amyloid cardiomyopathy.

AIMS: Tafamidis improves prognosis in patients with transthyretin amyloid cardiomyopathy (ATTR-CM). However, real-world data on the therapeutic effect of tafamidis are lacking. This study aimed to evaluate the clinical course, outcomes, and effectivity monitoring of the therapeutic effect of tafamidis in patients with ATTR-CM. METHODS AND RESULTS: This is a single-centre, retrospective observational study. We evaluated the clinical characteristics and outcomes in 125 consecutive patients with wild-type ATTR-CM (ATTRwt-CM) treated with tafamidis (treatment group) and 55 untreated patients (treatment-naïve group). We monitored the therapeutic effect of tafamidis for 12 months by evaluating serial cardiac biomarker and imaging findings. The treatment group had significantly more favourable outcome in all-cause mortality and hospitalization due to heart failure than the treatment-naïve group in both the entire cohort (P < 0.01) and the propensity score-matched cohort (P < 0.05). Kaplan-Meier survival curves showed that tafamidis treatment significantly reduced all-cause mortality (P = 0.03, log-rank test), with the curves diverging after approximately 18 months of treatment in the propensity score-matched cohort. On inverse probability of treatment weighting analysis, tafamidis treatment showed a reduced all-cause mortality [hazard ratio (HR), 0.31; 95% confidence interval (CI), 0.11-0.93; P = 0.04]. High-sensitivity cardiac troponin T (hs-cTnT) > 0.05 ng/mL, B-type natriuretic peptide (BNP) > 250 pg/mL, and estimated glomerular filtration rate (eGFR) < 45 mL/min/1.73 m2 scored 1 point each. Multivariate logistic regression analysis revealed that a high score (2-3 points) was a significantly poor prognostic factor of composite clinical outcomes, including all-cause death and hospitalization for heart failure (HR, 1.55; 95% CI, 1.22-1.98; P < 0.01) for patients in the treatment group. After 12 months of tafamidis treatment, hs-cTnT levels decreased significantly [0.054 (0.036-0.082) vs. 0.044 (0.033-0.076); P = 0.002], with no significant changes in BNP levels, echocardiographic parameters, native T1 value, and extracellular volume fraction on cardiac magnetic resonance imaging. CONCLUSIONS: The prognosis of patients with ATTRwt-CM treated with tafamidis was more favourable than that of untreated patients. Patient stratification combined with biomarkers (hs-cTnT, BNP, and eGFR) predicted clinical outcomes. hs-cTnT may be a useful biomarker for evaluating the therapeutic effect of tafamidis.

Dynamic change of mitral regurgitation after myocardial reverse remodelling: a case report.

Background: Chronic mitral regurgitation can be primary (degenerative) or secondary (functional); each has its own aetiology, treatment approach, and prognosis. A combination of the two types of regurgitation can lead to unexpected haemodynamic changes. Case summary: A 72-year-old woman presented to our hospital with dyspnoea on exertion, moist cough, and orthopnoea. At admission, transthoracic echocardiography (TTE) findings revealed severely reduced left ventricular ejection fraction, dilation of the left ventricle and left atrium, mild mitral regurgitation with prolapse of the posterior leaflet, and bilateral leaflet tethering. She was diagnosed with idiopathic cardiomyopathy with mild mitral regurgitation. After compensation of heart failure, angiotensin-receptor blocker and beta-blocker treatment were initiated, and the dose was subsequently titrated. At 7 months after initiating medical therapy, TTE showed significant improvement of the left ventricular ejection fraction, disappearance of left ventricular dilation (reverse remodelling), and mitral valve tethering. However, posterior leaflet prolapse became apparent, and mitral regurgitation blowing became more severe. Chordal lengthening, leaflet thickening, and degeneration were observed, but there were no ruptured chordae. Successful surgical repair of the mitral and tricuspid valves was performed. Discussion: In this unusual mitral regurgitation case, the regurgitation worsened following an improvement of cardiac function due to the loss of tethering from a reduction of the left ventricular diameter and an increase in closing force by increasing the left ventricular contractile force. Eventually, mitral regurgitation prolapse became apparent. Therefore, we should consider that reverse remodelling may exacerbate mitral regurgitation.

Correlation Between Cardiac Images, Biomarkers, and Amyloid Load in Wild-Type Transthyretin Amyloid Cardiomyopathy.

Background Several imaging parameters and biomarkers provide diagnostic and prognostic information for wild-type transthyretin amyloid cardiomyopathy. However, the relevance of these parameters and their association with cardiac amyloid load requires further substantiation. We aimed to elucidate the association of imaging parameters obtained using 99mTc-labeled pyrophosphate scintigraphy, cardiovascular magnetic resonance imaging, global longitudinal strain (GLS), and cardiac biomarkers with cardiac amyloid load in patients with wild-type transthyretin amyloid cardiomyopathy. Methods and Results Eighty-eight patients with wild-type transthyretin amyloid cardiomyopathy who underwent 99mTc-labeled pyrophosphate scintigraphy and cardiovascular magnetic resonance were retrospectively evaluated. Quantitative cardiac amyloid load was obtained from 61 patients after myocardial biopsy. Correlations were assessed using Pearson's correlation coefficient applied to medical record data. The mean heart to contralateral ratio, native T1, extracellular volume, and GLS were 1.91±0.36, 1419.4±56.4 ms, 56.5±13.6%, and -9.4±2.5%, respectively. Median high-sensitivity cardiac troponin T (hs-cTnT) and BNP (B-type natriuretic peptide) levels were 0.0478 (0.0334-0.0691) ng/mL and 213.8 (125.8-392.7) pg/mL, respectively. The mean cardiac amyloid load was 22.9±15.0%. The heart to contralateral ratio correlated significantly with native T1 (r=0.397), extracellular volume (r=0.477), GLS (r=0.363), cardiac amyloid load (r=0.379), and Ln (hs-cTnT) (r=0.247). Further, cardiac amyloid load correlated significantly with native T1 (r=0.509), extracellular volume (r=0.310), GLS (r=0.446), and Ln (hs-cTnT) (r=0.354). Compared with BNP, hs-cTnT levels better correlated with several imaging parameters and cardiac amyloid load. Conclusions Increased cardiac amyloid load correlated with increased 99mTc-labeled pyrophosphate positivity, native T1, extracellular volume, and hs-cTnT levels, and an impaired GLS, suggesting that imaging parameters and cardiac biomarkers may reflect histological and functional changes attributable to amyloid deposition in the myocardium.

Sex-related differences in the clinical characteristics of wild-type transthyretin amyloidosis cardiomyopathy.

BACKGROUND: A significant male predominance has been reported in wild-type transthyretin amyloid cardiomyopathy (ATTRwt-CM). Hence, female cases of ATTRwt-CM are overlooked, and sex-related differences in ATTRwt-CM remain unclear. This study aimed to examine sex-related differences in clinical characteristics and diagnostic approaches in ATTRwt-CM. METHODS: We retrospectively analyzed 199 consecutive patients who were diagnosed with ATTRwt-CM and evaluated sex-related differences in clinical characteristics, imaging parameters, biomarkers, and diagnostic approaches. RESULTS: Twenty-nine patients (15%) were female. These female patients were significantly older at diagnosis (77.1 ± 6.5 years vs. 82.9 ± 4.8 years; p<0.001) and had a more advanced New York Health Association functional class (2.2 ± 0.7 vs. 2.6 ± 0.8; p = 0.006) than their male counterparts. The median B-type natriuretic peptide levels were significantly higher (236 pg/mL vs. 394 pg/mL; p = 0.017) in female patients. Echocardiography revealed that the mean interventricular septum diameter was thinner (15.7 ± 2.6 mm vs. 14.1 ± 2.5 mm; p = 0.004) and left ventricular ejection fraction (LVEF) was preserved (51.2 ± 10.2% vs. 57.2 ± 9.1%; p = 0.003) in female patients. The mean heart-to-contralateral ratio obtained using 99mTc-labeled pyrophosphate (99mTc-PYP) was significantly lower (1.89 ± 0.33 vs. 1.63 ± 0.20; p < 0.001), moderate to severe aortic stenosis was more frequently observed (5% vs. 45%; p < 0.001), and the frequency of histological diagnosis was significantly lower (77% vs. 59%; p = 0.036) in female patients. CONCLUSIONS: Female patients with ATTRwt-CM were predominantly octogenarians and less hypertrophic and had preserved LVEF and weaker cardiac uptake of the 99mTc-PYP tracer compared with male patients. These characteristics contribute to the underdiagnosis of ATTRwt-CM in female patients.

A simple staging system using biomarkers for wild-type transthyretin amyloid cardiomyopathy in Japan.

AIMS: It has been reported that a staging system combining N-terminal pro-B-type natriuretic peptide and high-sensitivity troponin T (hs-cTnT) or estimated glomerular filtration rate (eGFR) is useful in patients with wild-type transthyretin amyloid cardiomyopathy (ATTRwt-CM). However, these studies were mainly conducted in Western countries, and their usefulness for the Japanese population is unclear. We examined and validated the staging system using hs-cTnT, eGFR, and B-type natriuretic peptide (BNP) in Japanese patients with ATTRwt-CM. METHODS AND RESULTS: We retrospectively evaluated 176 patients with ATTRwt-CM. The cut-off values of hs-cTnT and eGFR were selected as 0.05 ng/mL and 45 mL/min/1.73 m2 , respectively, based on a previous report. The optimal cut-off value of BNP was 255.6 pg/mL to predict all-cause mortality (sensitivity, 75%; specificity, 58%; area under the curve, 0.69; 95% confidence interval [CI], 0.61-0.78; P < 0.001) based on a receiver operating characteristic curve. We defined the cut-off value of BNP as 250 pg/mL. Increased hs-cTnT (>0.05 ng/mL) and BNP (>250 pg/mL) and decreased eGFR (<45 mL/min/1.73 m2 ) were significant predictors of poor prognosis (P < 0.05). We calculated the score by adding 1 point if hs-cTnT and BNP levels increased or eGFR decreased by more than the cut-off value. The hazard ratio of all-cause death adjusted by age and sex, using score 0 as a reference, was 0.44 (95% CI 0.08-2.49, P = 0.44) for score 1, 3.69 (95% CI 1.21-11.21, P = 0.02) for score 2, and 5.40 (95% CI 1.57-18.54, P = 0.007) for score 3. We divided patients into a low score group (0-1 point) and high score group (2-3 points). Kaplan-Meier analyses revealed significant differences in all-cause death and rehospitalization for heart failure (log rank test; P < 0.001), and after adjusting for sex and age, the hazard ratio of all-cause death was 6.96 (95% Cl 2.88-16.83, P < 0.001) and that for rehospitalization for heart failure was 4.27 (95% Cl 2.26-8.07, P < 0.001) in the high-risk group, compared with those in the low-risk group. The median survival period was 32.0 months in the high-risk group. CONCLUSIONS: This simple staging system, which combines hs-cTnT, BNP, and eGFR, was useful for predicting prognosis in Japanese patients with ATTRwt-CM. This system can objectively evaluate the disease progression of ATTRwt-CM and may be useful for patient selection for disease-modifying therapy.

Prognostic value of right ventricular global longitudinal strain in transthyretin amyloid cardiomyopathy.

BACKGROUND: This study was performed to investigate whether right ventricular global longitudinal strain (RV-GLS) provides prognostic information in patients with wild-type transthyretin amyloid cardiomyopathy (ATTRwt-CM). METHODS AND RESULTS: Among 129 patients who were diagnosed with ATTRwt-CM at Kumamoto University Hospital from December 2002 to December 2019, 111 patients who had enough information for two-dimensional speckle tracking imaging were retrospectively analyzed. During a median follow-up of 615 days, 26 cardiovascular deaths occurred. Compared with patients in the non-event group, those in the cardiovascular death group were significantly older (81.1 ±â€¯7.4 years vs. 78.2 ±â€¯6.2 years, p = 0.009) and had significantly higher interventricular septal thickness in diastole (16.6 ±â€¯3.1 mm vs. 15.3 ±â€¯2.4 mm, p = 0.048), lower RV-GLS (10.9 ±â€¯2.7% vs. 12.8 ±â€¯3.5%, p = 0.010), and lower right ventricular free wall longitudinal strain (RVFWLS) (13.1 ±â€¯3.3% vs. 15.5 ±â€¯3.8%, p = 0.004). In the univariate Cox proportional hazard analysis, age, left atrial volume index (LAVI), RV-GLS, and RVFWLS were significantly associated with cardiovascular death [age, hazard ratio (HR), 1.10; 95% confidence interval (CI), 1.02-1.19, p = 0.010; LAVI, HR, 1.02; 95% CI, 1.00-1.03, p = 0.009; RV-GLS, HR, 0.86; 95% CI, 0.75-0.97, p = 0.017; RVFWLS, HR 0.89; 95% CI, 0.79-1.00; p = 0.041]. Multivariable Cox proportional hazard analysis showed RV-GLS was significantly and independently associated with cardiovascular death in patients with ATTRwt-CM (HR, 0.86; 95% CI, 0.74-0.99; p = 0.038). Receiver operating characteristic analysis showed that the area under the curve of RV-GLS for cardiovascular death was 0.668 and that the best cut-off value of RV-GLS was 11.59% (sensitivity, 69.2%; specificity, 63.5%). In the Kaplan-Meier analysis, patients with ATTRwt-CM who had low RV-GLS (<11.59%) had a significantly higher probability of total cardiovascular death (p = 0.004) and heart failure-related hospitalization (p = 0.013). CONCLUSION: RV-GLS has significant prognostic value in patients with ATTRwt-CM and provides greater prognostic power than conventional echocardiographic findings.

Time-dependent change of relative apical longitudinal strain index in patients with wild-type transthyretin amyloid cardiomyopathy.

Aim: This study was conducted to investigate the meaning of left ventricular (LV) apical sparing in patients with wild-type transthyretin amyloid cardiomyopathy (ATTRwt-CM). Methods and results: 165 patients who were diagnosed with ATTRwt-CM at Kumamoto University Hospital from January 2002 to December 2020 and had sufficient data for two-dimensional speckle tracking echocardiography were enrolled. Of these, 86 patients (52 %) had LV apical sparing (relative apical longitudinal strain index (RapLSI) > 1.0). Multivariable logistic regression analysis revealed the following variables were significantly associated with LV apical sparing: interventricular septal thickness in diastole (odds ratio (OR), 1.19; 95 % confidence interval (CI), 1.01-1.41; p < 0.05); E/e' ratio (OR, 1.06; 95 % CI, 1.00-1.11; p < 0.05); and heart-to-contralateral ratio by 99mTc-labeled pyrophosphate scintigraphy (OR, 3.40; 95 % CI, 1.07-10.83; p < 0.05).Next, we compared RapLSI at the time of diagnosis with that during the follow-up period (396 days (346-458) after diagnosis) in 92 patients. RapLSI increased significantly during the follow-up period compared with RapLSI at diagnosis in the non-LV apical sparing group (0.89 ± 0.32 vs 0.74 ± 0.18, p < 0.01) but not in the LV apical sparing group (1.33 ± 0.53 vs 1.39 ± 0.45, p = 0.46). A total of 12 patients (29 %) in the non-LV apical sparing group developed LV apical sparing and 11 patients (22 %) in LV apical sparing group diminished LV apical sparing during the follow-up period. Conclusion: Approximately half of ATTRwt-CM patients did not have LV apical sparing at diagnosis. Because RapLSI in ATTRwt-CM significantly changed over time, repeated two-dimensional speckle tracking analysis is important for suspected ATTR-CM patients.

Preclinical diagnosis of wild-type transthyretin amyloid cardiomyopathy in a patient undergoing carpal tunnel release.

Wild-type transthyretin amyloid cardiomyopathy (ATTRwt-CM) has received increased attention because of its novel treatment options. Carpal tunnel syndrome (CTS) is known as early symptoms in transthyretin amyloidosis (ATTR) preceding cardiac involvement and one of the "red flags" for ATTR-CM. A 64-year-old man underwent carpal tunnel release for carpal tunnel syndrome at 62 years. He was diagnosed with wild-type ATTR due to deposition of transthyretin (TTR) amyloid in flexor tenosynovium specimens and no TTR gene mutation. Examination for detection of cardiac involvement was performed after the operation, and there were no definitive findings of ATTR-CM; however, an early stage of ATTR-CM remained a possibility. Serial image evaluation and biomarker analysis revealed positive findings for ATTR-CM, and we performed an endomyocardial biopsy, resulting in the detection of amyloid deposition. He was diagnosed with ATTRwt-CM 2 years after the operation, and even then, he had no heart failure symptoms. Early diagnosis and treatment are important for the improvement of clinical outcomes in patients with ATTRwt-CM. TTR deposition in the ligaments or tendons is often observed in patients with CTS and should be considered at high risk of future ATTR-CM. Serial follow-up of these patients may enable the diagnosis of preclinical ATTR-CM. .

Prognostic value of left atrial strain in patients with wild-type transthyretin amyloid cardiomyopathy.

AIMS: This study was performed to investigate whether left atrial (LA) strain by echocardiography provides prognostic information in patients with wild-type transthyretin amyloid cardiomyopathy (ATTRwt-CM). METHODS AND RESULTS: Among 129 patients who were diagnosed with ATTRwt-CM at Kumamoto University Hospital from December 2002 to December 2019, 113 patients who had enough information for two-dimensional speckle tracking echocardiography were enrolled in this study. During a median follow-up of 668 days, 28 cardiovascular deaths occurred. Compared with patients in the non-event group, those in the cardiovascular death group were significantly older (81.5 ± 7.4 vs. 78.1 ± 6.1 years, P < 0.01), had a lower incidence of carpal tunnel syndrome (21% vs. 47%, P < 0.05), and had a higher high-sensitivity cardiac troponin T [0.085 (0.063-0.105) vs. 0.049 (0.036-0.079) ng/mL, P < 0.01] and B-type natriuretic peptide concentrations [419 (239-541) vs. 271 (155-462) pg/mL, P < 0.01] and lower estimated glomerular filtration rate (41.8 ± 15.4 vs. 53.4 ± 14.6 mL/min/1.73 m2 , P < 0.01). Electrocardiography showed higher rate of a V1-V3 QS pattern (52% vs. 24%, P < 0.01) and complete left bundle branch block (27% vs. 6%, P < 0.01), and echocardiography showed a significantly lower peak LA strain rate during the contraction phase (0.16 ± 0.13 vs. 0.28 ± 0.27 S-1 , P < 0.05), LA strain during the reservoir phase (LASr) (5.84 ± 2.41 vs. 8.22 ± 4.05%, P < 0.01), and peak LA strain rate during the reservoir phase (0.26 ± 0.09 vs. 0.33 ± 0.15 S-1 , P < 0.05) in the cardiovascular death group than in non-event group. By contrast, conventional echocardiographic findings were not significantly different between these two groups. After adjusting for conventional predictive factors of ATTRwt-CM (age, high-sensitivity cardiac troponin T and B-type natriuretic peptide concentrations, and estimated glomerular filtration rate), multivariable Cox proportional hazard analyses showed that LASr was significantly and independently associated with cardiovascular death in patients with ATTRwt-CM (odds ratio, 0.84; 95% confidence interval, 0.72-0.98; P < 0.05). After adjusting for age and echocardiographic findings associated with cardiovascular death (LA volume index and peak LA strain rate during the contraction phase), LASr was significantly and independently associated with cardiovascular death in patients with ATTRwt-CM (odds ratio, 0.83; 95% confidence interval, 0.70-0.98; P < 0.05). Receiver operating characteristic curve analysis showed that the area under the curve of LASr for cardiovascular death was 0.686 and that the best cut-off value of LASr was 6.69% (sensitivity, 62.4%; specificity, 64.3%). In the Kaplan-Meier analysis, patients with low LASr (<6.69%) had a significantly higher probability of total cardiovascular death (P < 0.05) and heart failure-related hospitalization (P < 0.05). CONCLUSIONS: Left atrial strain during the reservoir phase provides significant prognostic value in patients with ATTRwt-CM even after adjusting for conventional predictive factors.

Detection of acquired von Willebrand syndrome after ventricular assist device by total thrombus-formation analysis system.

AIMS: Bleeding is a serious complication in patients with continuous-flow left ventricular assist device (CF-LVAD). Acquired von Willebrand syndrome (AVWS; type 2A) develops because of high shear stress inside the pumps and is a cause of bleeding complication. Although von Willebrand factor (vWF) multimer analysis is useful for diagnosing AVWS, it is only performed in specialized research institutes. A novel microchip flow chamber system, the total thrombus-formation analysis system (T-TAS), is a point-of-care system to evaluate the thrombus-formation process and useful for monitoring platelet thrombus-formation capacity in patients receiving antiplatelet therapy and the diagnosis and evaluation of the clinical severity of von Willebrand disease type 1. However, little is known about the association between AVWS and platelet thrombus-formation capacity evaluated by T-TAS in patients with CF-LVAD. We aimed to evaluate the utility of T-TAS for easy detection of AVWS in patients with CF-LVAD. METHODS AND RESULTS: We simultaneously evaluated the vWF large multimers and T-TAS parameters in four consecutive patients with axial-type CF-LVAD and eight control patients treated with aspirin and warfarin. vWF large multimer index was defined as the proportion of large multimers in total vWF derived from a normal control plasma. T-TAS analyses different thrombus-formation processes using two microchips with different thrombogenic surfaces. PL24 -AUC10 levels in the platelet (PL) chip are highly sensitive for platelet functions, while AR10 -AUC30 levels in the atheroma (AR) chip allow the assessment of the overall haemostatic ability. vWF large multimer index and T-TAS parameters were decreased in all patients with CF-LVAD. The mean PL24 -AUC10 level (5.4 ± 2.9 vs. 219 ± 67; P < 0.01), AR10 -AUC30 level (338 ± 460 vs. 1604 ± 160; P < 0.01) and vWF large multimer index (49 ± 11% vs. 112 ± 27%; P < 0.01) were significantly lower in the patients with CF-LVAD than in control patients. One patient showed changes in T-TAS levels before and after implantation of CF-LVAD. PL24 -AUC10 and AR10 -AUC30 levels decreased from 438.1 to 5.0 and from 1667.9 to 1134.3, respectively. CONCLUSIONS: In patients with CF-LVAD, the platelet thrombus-formation capacity was extremely impaired because of AVWS, and T-TAS parameters could detect the presence of AVWS. T-TAS can be used for easy detection of AVWS as a point-of-care testing. Further studies with a large sample size are needed to validate our results in several LVAD models and evaluate the prognostic value of bleeding complications and thromboembolism in patients with LVAD.

Clinical characteristics and natural history of wild-type transthyretin amyloid cardiomyopathy in Japan.

AIMS: The focus on wild-type transthyretin amyloid cardiomyopathy (ATTRwt-CM) is increasing because of novel treatment options. There is currently no report on a large number of Japanese patients with ATTRwt-CM. The study aimed to examine the characteristics and prognosis of ATTRwt-CM in Japan. METHODS AND RESULTS: Consecutive patients (78.5 ± 6.4 years old at diagnosis) with ATTRwt-CM diagnosed at Kumamoto University Hospital between December 2002 and December 2019 were retrospectively reviewed. Data, including demographic characteristics, co-morbidities, clinical manifestations at diagnosis, laboratory results, electrocardiographic and echocardiographic data, imaging and pathological findings, and treatment were obtained. Of 129 patients included in this study, 110 patients (85%) were male. The median period from initial symptom onset to diagnosis was 15.5 (2-75) months. Heart failure was the most common clinical manifestation leading to diagnosis (61%) and initial manifestations (49%). Of 106 patients, carpal tunnel syndrome was observed in 57 patients (54%), and the median period from initial symptom onset to diagnosis was 96 (48-120) months. Histopathological confirmation of transthyretin amyloid was achieved in 94 patients (73%), including 66 (51%) and 28 cases (22%) with endomyocardial and extracardiac biopsies. During the observation period (median 15.0 [inter-quartile range, 5.4-33.2] months after diagnosis), 34 patients (26%) died. Of these, 27 patients (79%) had cardiovascular deaths (heart failure, 25; sudden death, two). The median survival duration was 58.9 months and the 5 years' survival rate was 48%. According to a multivariate Cox hazard analysis, age [hazard ratio (HR), 1.14; 95% confidence interval (CI), 1.05-1.23, P = 0.002] and low serum sodium levels (HR, 0.89; 95% CI, 0.79-0.996; P = 0.04) contributed to all-cause mortality, and low serum sodium levels contributed to hospitalization for heart failure (HR, 0.86; 95% CI, 0.77-0.96; P = 0.005). CONCLUSIONS: Clinical characteristics and prognosis of ATTRwt-CM patients in Japan were examined. Carpal tunnel syndrome can be considered an indication for diagnosis of ATTRwt-CM. Age and low serum sodium level were significant predictive factors of all survival outcomes. The clinical features of ATTRwt-CM should be recognized to provide appropriate treatment.