Prevalence of amyloid transthyretin cardiomyopathy in elderly subjects from the general population: first results from the CATCH study

Background

Amyloid transthyretin cardiomyopathy (ATTR-CM) has become treatable. Wild-type ATTR-CM is an age-related disorder. Establishing the exact prevalence of ATTR-CM in elderly subjects from the general population may be useful for healthcare providers and policy makers alike.

Methods

The Characterizing the burden of Amyloid Transthyretin CardiomyopatHy in the elderly (CATCH) study is a population screening on all subjects aged ≥65 years followed by general practitioners working in a part of Tuscany (Italy) where there is no cluster of variant ATTR. The study started on March 12, 2021 and is ongoing. The first step of the evaluation includes clinical history and physical examination, electrocardiogram, transthoracic echocardiogram, and blood sampling with measurement of N-terminal pro-B-type natriuretic peptide and high-sensitivity (hs) troponin T. The following elements are searched: 1) any clinical red flag of amyloidosis (history of carpal tunnel syndrome, lumbar spine stenosis, etc.), 2) interventricular septal thickness ≥12 mm or other echocardiographic red flags, 3) hs-troponin T higher than the upper reference limit (14 ng/L). Patients with any of these elements are referred to a second step including diphosphonate scintigraphy and the search for a monoclonal protein in the serum and urine. The standard diagnostic workup for CA is then followed until the diagnosis is confirmed or discarded.

Results

As of October 13, 2021, 514 subjects ≥65 years have been evaluated for possible participation. Among them, 135 (26%) could not be contacted, were reluctant to enter the study, died before being contacted, or were bedridden. Out of the other 379 subjects, 329 (87%) have already undergone the first step. Forty percent of individuals (n=132) have been referred to the second step. Thirteen subjects have declined (10%); 69 patients have undergone diphosphonate scintigraphy and the search for a monoclonal protein (while the other 50 are awaiting these exams). Two subjects showed an intense myocardial uptake of the diphosphonate tracer (Perugini score 2–3) and no monoclonal protein, and were then diagnosed with ATTR-CM. They were both women, aged 83 and 78 years, both mildly symptomatic for dyspnea (New York Heart Association II) and with unexplained hypertrophy. The search for TTR gene mutation was negative in the first case and is still ongoing in the second. Based on these preliminary data, the prevalence of ATTR-CM in the elderly population can be calculated as 2/266=0.8% (Figure 1).

Conclusions

The CATCH study is expected to enroll at least 1,000 subjects and will provide the first data on the epidemiology of ATTR-CM in elderly subjects. Based on an interim analysis, almost 1 in 100 individuals ≥65 years has ATTR-CM.

Funding Acknowledgement

Type of funding sources: None.

P288 PREVALENCE OF AMYLOID TRANSTHYRETIN CARDIOMYOPATHY IN ELDERLY SUBJECTS FROM THE GENERAL POPULATION: FIRST RESULTS FROM THE CATCH STUDY

Background

Amyloid transthyretin cardiomyopathy (ATTR–CM) has become treatable. Wild–type ATTR–CM is an age–related disorder. Establishing the exact prevalence of ATTR–CM in elderly subjects from the general population may be useful for healthcare providers and policy makers.

Methods

The Characterizing the burden of Amyloid Transthyretin CardiomyopatHy in the elderly (CATCH) study is a population screening on all subjects aged ≥65 years followed by general practitioners in a part of Tuscany (Italy) where there is no cluster of variant ATTR. The study started on March 12, 2021 and is ongoing. Patients with 1) any clinical red flag of amyloidosis, 2) interventricular septal thickness ≥12 mm or other echocardiographic red flags, and/or 3) hs–troponin T > 14 ng/L are referred to diphosphonate scintigraphy and search for a monoclonal protein.

Results

As of October 13, 2021, 514 subjects ≥65 years have been evaluated for possible participation. Among them, 135 (26%) could not be contacted, were reluctant to enter the study, died before being contacted, or were bedridden. Out of the other 379 subjects, 329 (87%) have already undergone the first step. Forty percent of individuals (n = 132) have been referred to the second step. Thirteen subjects have declined (10%); 69 patients have undergone diphosphonate scintigraphy and the search for a monoclonal protein (while the other 50 are awaiting these exams). Two subjects showed an intense myocardial uptake of the diphosphonate tracer (Perugini score 2–3) and no monoclonal protein, and were then diagnosed with ATTR–CM. They were both women, aged 83 and 78 years, both mildly symptomatic for dyspnea (New York Heart Association II) and with unexplained hypertrophy. The search for TTR gene mutation was negative in the first case and is still ongoing in the second. Based on these preliminary data, the prevalence of ATTR–CM in the elderly population can be calculated as 2/266=0.8%.

Conclusions

The CATCH study is expected to enroll at least 1,000 subjects and will provide the first data on the epidemiology of ATTR–CM in elderly subjects. Based on an interim analysis, almost 1 in 100 individuals ≥65 years has ATTR–CM.

Amyloid deposits and fibrosis on left ventricular endomyocardial biopsy correlate with extracellular volume in cardiac amyloidosis

Background

The relative contribution of amyloid and fibrosis to extracellular volume expansion in cardiac amyloidosis (CA) has never been defined.

Methods

We included all patients diagnosed with amyloid light-chain or transthyretin (AL/ATTR) CA at a tertiary referral center between 2014 to 2020 and undergoing a left ventricular (LV) endomyocardial biopsy (EMB).

Results

Patients (n=37) were more often male (92%), with a median age of 72 years (68–81). Lambda+ AL was found in 14/19 AL cases (38%) and kappa+ AL in 5/19 (14%), while TTR was detected in the other 18 cases (48%). Amyloid deposits accounted for 15% of tissue sample area (10–30%), without significant differences between AL and ATTR. All patients displayed myocardial fibrosis, with a median extent of 15% of tissue samples (10–23%, range 5–60%), in the absence of spatial overlap with amyloid deposits. Interstitial fibrosis was often associated with mild and focal subendocardial fibrosis. The extent of fibrosis or the combination of amyloidosis and fibrosis did not differ significantly between ATTR and AL subgroups. In 20 patients with myocardial T1 mapping at cardiac magnetic resonance (CMR), the combined amyloid and fibrosis extent displayed a modest correlation with extracellular volume (ECV; r=0.661, p=0.001). The combined amyloid and fibrosis extent correlated with high-sensitivity troponin T (p=0.035) and N-terminal pro-B-type natriuretic peptide (p=0.002) serum levels.

Conclusions

Extracellular spaces in CA are enlarged to a similar extent by amyloid deposits and fibrotic tissue. Their combination can better explain the increased ECV at CMR and circulating biomarkers than amyloid extent alone.

Funding Acknowledgement

Type of funding sources: None.

Reverse remodelling criteria to predict cardiovascular death in heart failure with reduced or mid-range ejection fraction

Aims

Reverse remodelling (RR) is the recovery from left ventricle (LV) dilatation and dysfunction. There are no established definitions of RR. We sought to identify RR criteria that better predicted cardiovascular death.

Methods and results

Forty-two studies used 25 criteria to define RR, most commonly (n=12) as LV end-systolic volume (LVESV) reduction ≥15%. We evaluated 927 patients with LV ejection fraction (LVEF) <50% undergoing 2 echocardiograms within 12±2 months. Over a median 2.8-year follow-up after the second echocardiogram (1.3–4.9), 123 cardiovascular deaths occurred (13%). Model 1 included age, LVEF, N-terminal pro-B-type natriuretic peptide (NT-proBNP), ischaemic aetiology, cardiac resynchronization therapy (CRT), estimated glomerular filtration rate (eGFR), New York Heart Association (NYHA), and LVESV index (LVESVi), and Model 2 the validated 3C-HF score. Two RR criteria proved particularly effective in risk reclassification over Model 1 and Model 2: LVEF increase ≥1 category (severe [LVEF ≤30%], moderate [LVEF 31–40%], mild LV dysfunction [LVEF 41–55%] and normal LV function [LVEF ≥56%]), and LVEF increase >10 U. The same 2 criteria yielded independent prognostic significance and improved reclassification also in patients with LVEF <40% or LVEF ≤35%. LVEF increase ≥1 category and LVEF increase >10 U displayed a stronger prognostic value than LVESV reduction ≥15%, both in the whole population and the subsets with LVEF <40% or ≤35%.

Funding Acknowledgement

Type of funding sources: None.

Reverse remodelling, changes in diastolic function and their prognostic value compared to natriuretic peptides

Background

Reverse remodelling (RR) is the recovery from left ventricular (LV) dilation and dysfunction in response to treatment for heart failure (HF). RR is usually associated with improved prognosis. The impact of RR on indices of diastolic function, and the relative prognostic value of RR, changes in diastolic function and natriuretic peptide levels are currently unknown.

Methods

We analysed data from patients with stable systolic HF (LV ejection fraction [LVEF] <50%) undergoing 2 transthoracic echocardiograms (TTE) within 12±2 months. RR was defined as a ≥15% reduction in LV end-systolic volume index (LVESVi). The follow-up started after the second TTE.

Results

927 patients were evaluated (68±12 years; median LVEF 35% [interquartile interval 30–43%]; 27% women; 52% ischaemic aetiology). Patients experiencing RR (n=286, 31%) displayed more prominent positive changes in several parameters reflecting diastolic dysfunction, namely E/e' ratio, left atrial volume index (LAVi), and systolic pulmonary artery pressure (sPAP), as well as N-terminal fraction of pro-B-type natriuretic peptide (NT-proBNP; Figure). In the whole population, percent changes (Δ%) LVESVi displayed weak but significant correlations with Δ% E/e' (r=0.237, p<0.001), LAVi (r=0.316, p<0.001), and sPAP (r=0.158, p<0.001), and also with Δ% NT-proBNP (r=0.279, p<0.001). There were 123 cardiovascular deaths and 4 heart transplantations over 2.8 years (1.3–4.9). Δ% LVESVi, RR, Δ% sPAP and Δ% NT-proBNP were univariate predictors of this endpoint. In 2 multivariable models including Δ% sPAP and Δ% NT-proBNP and either RR or Δ% LVESVi, only Δ% NT-proBNP emerged as independent predictor of outcome (hazard ratio 1.01, 95% confidence interval 1.01–1.02; p<0.001).

Conclusions

A recovery of LV geometry is accompanied by positive modifications in several indices related to diastolic function, as well as a decrease in NT-proBNP levels. Percent changes in NT-proBNP over 12 months are stronger predictors of outcome than variations in LV geometry or sPAP.

Funding Acknowledgement

Type of funding source: None