Health-related quality of life among transthyretin amyloid cardiomyopathy patients

Clinical and biochemical characterization of asymptomatic carriers and symptomatic patients with hereditary transthyretin amyloidosis caused by TTR V30L mutation

BACKGROUND

Hereditary transthyretin amyloidosis (ATTR) is an autosomal dominant disease characterized by amyloid fibril deposition. The TTR c.148G > T mutation (V30L) in ATTR is rarely reported, and its biochemical properties are unknown.

METHODS

Seven patients and two asymptomatic carriers from two unrelated families diagnosed with V30L variant of ATTR were included. Data on clinical manifestations, laboratory examination, electrophysiology, ophthalmological corneal confocal microscopy (CCM), pathology and molecular biological experiments was collected and analyzed.

RESULTS

Most patients initially experienced paresthesia, with varying degrees of peripheral neuropathy, autonomic dysfunction, and cardiac involvement. Nerve conduction studies showed extensive motor and sensory nerve involvement in upper and lower limbs. CCM revealed reduced corneal nerve density and fiber length. Sural nerve biopsies indicated loss of myelinated nerve fibers, with neurogenic patterns in gastrocnemius muscle biopsies. Asymptomatic carriers had nearly normal electrophysiology but mild reductions in corneal nerve fiber density and length. Sural nerve biopsies in carriers showed mild reductions in small myelinated nerve fibers. V30L mutation impaired thermodynamic and kinetic stability of the mutant protein. Plasma TTR tetramer concentration was lower in ATTR V30L patients compared to healthy donors. Small molecule stabilizers failed to exhibit satisfactory inhibition on fibril formation of V30L mutation in vitro.

CONCLUSION

This study highlights the multisystem involvement in ATTR V30L patients, including neuropathy and cardiac issues. Both patients and carriers showed abnormalities in nerve conduction, corneal microscopy, and pathology. The V30L mutation impaired protein stability and reduced plasma TTR tetramer levels. Small molecule stabilizers were ineffective, indicating a need for alternative treatments.

Health-related quality of life is an independent predictor of mortality and hospitalisations in transthyretin amyloid cardiomyopathy: a prospective cohort study

PURPOSE

Transthyretin amyloid cardiomyopathy (ATTR-CM) is associated with severely impaired health-related quality of life (HRQL). HRQL is an independent predictor of outcome in heart failure (HF), but data on patients with ATTR-CM is scarce. This study therefore aims to evaluate the association of HRQL with outcome in ATTR-CM.

METHODS

Patients from our prospective ATTR-CM registry were assessed using the Kansas City cardiomyopathy questionnaire (KCCQ), the Minnesota living with HF questionnaire (MLHFQ), and the EuroQol five dimensions questionnaire (EQ-5D). Cox regression analysis was utilised to assess the impact of HRQL on all-cause mortality.

RESULTS

167 patients [80 years; interquartile range (IQR): 76-84; 80.8% male] were followed for a median of 27.6 (IQR: 9.7-41.8) months. The primary endpoint of all-cause mortality was met by 43 (25.7%) patients after a median period of 16.2 (IQR: 9.1-28.1) months. In a univariate Cox regression for mortality, a 10-point change in the KCCQ implied a hazard ratio (HR) of 0.815 [95%-confidence interval (CI): 0.725-0.916; p = 0.001], in the EQ-5D VAS of 0.764 (95%-CI: 0.656-0.889; p < 0.001), and 1.163 (95%-CI: 1.114-1.433; p < 0.001) in the MLHFQ. After adjustment for established biomarkers of HF, all-cause mortality was predicted independently by the EQ-5D VAS (HR: 0.8; 95%-CI: 0.649-0.986; p = 0.037; per 10 points) and the MLHFQ (HR: 1.228; 95%-CI: 1.035-1.458; p = 0.019; per 10 points).

CONCLUSION

HRQL is a predictor of outcome in ATTR-CM. The EQ-5D VAS and the MLHFQ predict survival independent of biomarkers of HF.

Exercise Hemodynamics and Mitochondrial Oxidative Capacity in Disease Stages of Wild-Type Transthyretin Amyloid Cardiomyopathy

BACKGROUND

Wild-type transthyretin amyloid (ATTRwt) cardiomyopathy is increasingly recognized in the development of heart failure. The link between cardiac performance, hemodynamics, and mitochondrial function in disease stages of ATTRwt has not previously been studied but may provide new insights into the pathophysiology and clinical performance of the patients.

METHODS AND RESULTS

The study investigated 47 patients diagnosed with ATTRwt at Aarhus University Hospital, Denmark. Patients were stratified according to the disease stages of the National Amyloidosis Centre (NAC) as NAC I with low levels of NT-proBNP (N-terminal pro-B-type natriuretic peptide) (NAC I-L, n=14), NAC I with high levels NT-proBNP (NAC I-H, n=20), and NAC II-III (n=13). Exercise testing with simultaneous right heart catheterization was performed in all patients. Endomyocardial biopsies were collected from the patients and the mitochondrial oxidative phosphorylation capacity was assessed. All NAC disease groups, even in the NAC I-L group, a significant abnormal increase in biventricular filling pressures were noted during exercise while the filling pressures was normal or near normal at rest. The inotropic response to exercise was reduced with diminished increase in cardiac output which was significantly more pronounced in the NAC I-H (Diff. -2.4, 95% CI (-4.2: -0.7), P=0.00) and the NAC II-III group (Diff: -3.1 L/min, 95% CI (-5.2: -1.1), P=0.00) compared with the NAC I-L group. The pulmonary artery wedge pressure to cardiac output ratio at peak exercise was significantly different between NAC I-L and NAC II-III (Diff: 1.6 mm Hg*min/L, 95% CI (0.01:3.3, P=0.04)). Patients with ATTRwt had a reduced oxidative phosphorylation capacity which correlated to left ventricular mass but not to cardiac output capacity.

CONCLUSIONS

An abnormal restrictive left ventricle and right ventricle response to exercise was demonstrated, even present in patients with early-stage ATTRwt. In more advanced disease stages a progressive impairment of the pressure-flow relationship was noted. The myocyte energetics is deranged but not associated to the contractile reserve or restrictive filling characteristics in ATTRwt.

Determinants of health status in older patients with transthyretin cardiac amyloidosis: a prospective cohort study

BACKGROUND

Whether, and to what extent, frailty and other geriatric domains are linked to health status in patients with transthyretin cardiac amyloidosis (ATTR-CA) is unknown.

AIMS

To determine the association of frailty with health status [defined by the Kansas City Cardiomyopathy Questionnaire (KCCQ)] in patients with ATTR-CA.

METHODS

Consecutive ATTR-CA patients undergoing cardiovascular assessment at a tertiary care clinic from September 2021 to September 2023 were invited to participate. KCCQ, frailty and social environment were recorded. Frailty was assessed using the modified Frailty Index (mFI), mapping 11 variables from the Canadian Study of Health and Aging (frailty ≥0.36).

RESULTS

Of 168 screened ATTR-CA patients, 138 [83% men, median age of 79 (75-84) years] were enrolled in the study. Median KCCQ was 66 (50-75). wtATTR-CA was the most prevalent form (N = 113, 81.9%). The most frequent cardiac variant was Ile68Leu (17/25 individuals with vATTR-CA). Twenty (14.5%) patients were considered frail, and prevalence of overt disability was 6.5%. At multivariable linear regression analysis, factors associated with worsening KCCQ were age at evaluation, the mFI, NYHA Class, and NAC Score. Gender, ATTR-CA type, phenotype, and LVEF were not associated with health status.

DISCUSSION

In older patients diagnosed with ATTR-CA, frailty, symptoms, and disease severity were associated with KCCQ.

CONCLUSIONS

Functional status is a determinant of quality of life and health status in older individuals with a main diagnosis of ATTR-CA. Future research may provide more in-depth knowledge on the association of frailty in patients with ATTR-CA with respect to quality of life and prognosis.

Health care resource use, diagnostic delay and disease burden in transthyretin amyloid cardiomyopathy in Sweden

AIMS

To estimate healthcare resource use and direct healthcare costs of Transthyretin Amyloid Cardiomyopathy (ATTR-CM) in Sweden over 12 months across severity stages as defined by the New York Heart Association (NYHA). Secondary to investigate the current diagnostic trajectory for patients with ATTR-CM in Sweden.

METHODS

A stratified inclusion of patients with a confirmed diagnosis of ATTR-CM in different NYHA classes. Data was extracted from medical records in two cardiology clinics in Sweden. Healthcare resource use data were retrospectively collected for 12 months.

RESULTS

38 patients were included, of whom 7 were in NYHA class II, 20 in class III and 4 in class IV. The total cost of health care per patient increased from SEK 69,000 (€6800) in NYHA stage II, SEK 219,000 (€21,500) in NYHA stage III, to SEK 638,000 (€62,900) in stage IV, mainly due to an increase in inpatient stays. Mean time (standard deviation, SD) from any cardiac related diagnosis prior to ATTR-CM diagnosis was 3.5 (3.1) years.

CONCLUSIONS

Advanced ATTR-CM stages are associated with significant healthcare costs, as patients more often require resource-intensive inpatient care. The current diagnostic trajectory of ATTR-CM in this study was characterized by a diagnostic delay of several years.

Burden of untreated transthyretin amyloid cardiomyopathy on patients and their caregivers by disease severity: results from a multicenter, non-interventional, real-world study

Background

The humanistic burden of transthyretin amyloid cardiomyopathy (ATTR-CM) is poorly defined.

Methods

An international study to comprehensively characterize the burden of ATTR-CM on patients naïve to disease-modifying therapy and their unpaid primary caregivers using study-specific and established surveys (patients: Kansas City Cardiomyopathy Questionnaire Overall Summary [KCCQ-OS], 12-Item Short Form Health Survey [SF-12], Hospital Anxiety and Depression Scale [HADS], Patient-Reported Outcomes Measurement Information System [PROMIS] Fatigue and Dyspnea; caregivers: SF-12, HADS, PROMIS Fatigue, Zarit Burden Interview [ZBI]). All data were summarized descriptively.

Results

208 patient and caregiver pairs were included. 86% of patients were male, median age was 81 years, and 91% (141/155 with genetic testing) had wild-type ATTR-CM. Patient responses characterized the mental and physical burden of ATTR-CM, which was numerically higher among those who were New York Heart Association (NYHA) class III (n = 43) vs. class I/II (n = 156). NYHA class III patients had particularly low KCCQ-OS (36) and SF-12 physical component (27) scores, and 67% had a HADS depression score ≥8. Caregivers (median age 68 years; 85% female; 59% spouse of the patient; median duration of caregiving 1.5 years) reported that NYHA III patients more frequently required help with a range of physical activities than NYHA class I/II patients. 51% of caregivers to NYHA class III patients reported at least a mild-to-moderate burden in the ZBI. A plain language summary of this paper can be found as a supplemental material.

Conclusions

Untreated ATTR-CM is a burden to both patients and their caregivers.