Left ventricular structure and function in transthyretin-related versus light-chain cardiac amyloidosis

Patisiran, an RNAi therapeutic for the treatment of hereditary transthyretin-mediated amyloidosis

Hereditary transthyretin-mediated amyloidosis is a rapidly progressive, heterogeneous disease caused by the accumulation of misfolded transthyretin protein as amyloid fibrils at multiple sites, and is characterized by peripheral sensorimotor neuropathy, autonomic neuropathy and/or cardiomyopathy. Current treatment options have limited efficacy and often do not prevent disease progression. Patisiran is a novel RNA interference therapeutic that specifically reduces production of both wild-type and mutant transthyretin protein. In Phase II, III and long-term extension studies in patients with hereditary transthyretin-mediated amyloidosis, patisiran has consistently slowed or improved progression of neuropathy. In addition, the Phase III trial demonstrated significant improvements in quality of life measures and indicators of cardiomyopathy. Here, we highlight efficacy and safety data from the patisiran clinical trial programme.

A rare variant of transthyretin-related amyloidosis associated with exclusive cardiomyopathy in a Hong Kong Chinese patient

Hereditary transthyretin-related amyloidosis (ATTR, MIM #105210), also previously known as familial amyloidotic polyneuropathy, is one of the most life-threatening types of amyloidosis. ATTR is inherited in autosomal dominant mode with variable penetrance. If untreated, it is a relentless and lethal disease. Patients typically present with polyneuropathy, carpal tunnel syndrome, autonomic insufficiency, cardiomyopathy, and gastrointestinal features, occasionally accompanied by vitreous opacities and renal insufficiency. Frequency of transthyretin (TTR)-related cardiac amyloidosis amongst Chinese populations is unknown. We report here a 63-year-old Chinese man suffering from TTR-related cardiac amyloidosis presented with exclusive cardiomyopathy. He had no other systemic involvement and no significant family history. Echocardiography revealed severe global myocardial impairment and left ventricular ejection fraction of 35%. Serum kappa-to-lambda ratio was normal. Genetic test detected a heterozygous TTR variant, NM_000371.3:c.425T > C p.(Val142Ala). To our knowledge, this is the first case of TTR-related cardiac amyloidosis caused by p.Val142Ala mutation reported in Asian patient. <Learning objective: This case highlights the importance to exclude transthyretin-related cardiac amyloidosis as a cause of extensive cardiomyopathy, despite the late disease onset and lack of systemic amyloidosis. High clinical suspicion and genetic testing is the key for early diagnosis.>.

Contemporary Imaging Diagnosis of Cardiac Amyloidosis

Cardiac amyloidosis is a rare disease that frequently presents as ventricular hypertrophy. However, diagnosis is not always easy or straightforward as there are several myocardial disorders that phenocopy cardiac amyloidosis. Here, we present a narrative review of the current modalities that are actively used or being developed for diagnosis and follow-up of cardiac amyloidosis. Although not all of the findings may be present in those with cardiac amyloidosis, there are some clues in each diagnostic step that help lead to confirmatory diagnosis of cardiac amyloidosis; we believe that cardiologists should be familiar with these clues.

A histopathologic schema to quantify the burden of cardiac amyloidosis: Relationship with survival and echocardiographic parameters

BACKGROUND

Despite routine use of echocardiographic parameters to evaluate the severity of cardiac amyloidosis (CA), this methodology has not been well validated. We developed a histopathologic schema for quantifying CA burden and evaluated its relationship with clinical outcomes. Additionally, echocardiographic parameters were tested as potential noninvasive indices of CA burden.

METHODS

We retrospectively studied 59 patients with CA (17 light chain, 42 transthyretin) who underwent endomyocardial biopsies. Light microscopy with staining was used to categorize CA burden as mild-to-moderate (<50%) or high (≥50%). Kaplan-Meier survival analysis was performed for the two groups. In 34 patients with good-quality echocardiograms, we measured left ventricular volumes, ejection fraction (EF), interventricular septal thickness (IVSt), posterior wall thickness (PWt), LV mass, lateral e'-velocity, and global longitudinal strain (GLS). These parameters were compared between the two groups.

RESULTS

Thirty-five patients had mild-to-moderate and 24 severe amyloid burden. Kaplan-Meier curves demonstrated a trend toward worse mortality with high CA burden, which was more common and associated with higher mortality specifically in transthyretin-type patients. Echocardiography-derived IVSt, PWt, and LV mass were directly related to CA burden, while LV EF, e'-velocity, and GLS magnitude were inversely related to CA burden.

CONCLUSIONS

Our findings provided a signal that CA burden is a clinically important entity with potentially valuable prognostic information. Echocardiographic parameters of LV anatomy and function correlate with histopathologic burden of CA, which is inversely related to survival. Further studies are needed to determine whether these parameters could be used as imaging biomarkers of treatment-related changes in CA burden.

Diagnosis of cardiac amyloidosis: a systematic review on the role of imaging and biomarkers

BACKGROUND

Cardiac Amyloidosis (CA) pertains to the cardiac involvement of a group of diseases, in which misfolded proteins deposit in tissues and cause progressive organ damage. The vast majority of CA cases are caused by light chain amyloidosis (AL) and transthyretin amyloidosis (ATTR). The increased awareness of these diseases has led to an increment of newly diagnosed cases each year.

METHODS

We performed multiple searches on MEDLINE, EMBASE and the Cochrane Database of Systematic Reviews. Several search terms were used, such as "cardiac amyloidosis", "diagnostic modalities cardiac amyloidosis" and "staging cardiac amyloidosis". Emphasis was given on original articles describing novel diagnostic and staging approaches to the disease.

RESULTS

Imaging techniques are indispensable to diagnosing CA. Novel ultrasonographic techniques boast high sensitivity and specificity for the disease. Nuclear imaging has repeatedly proved its worth in the diagnostic procedure, with efforts now focusing on standardization and quantification of amyloid load. Because the latter would be invaluable for any staging system, those spearheading research in magnetic resonance imaging of the disease are also trying to come up with accurate tools to quantify amyloid burden. Staging tools are currently being developed and validated for ATTR CA, in the spirit of the acclaimed Mayo Staging System for AL.

CONCLUSION

Cardiac involvement confers significant morbidity and mortality in all types of amyloidosis. Great effort is made to reduce the time to diagnosis, as treatment in the initial stages of the disease is tied to better prognosis. The results of these efforts are highly sensitive and specific diagnostic modalities that are also reasonably cost effective.

Management of the elderly patient with AL amyloidosis

Systemic immunoglobulin light chain (AL) amyloidosis is an aging-associated protein misfolding and deposition disease. This condition is caused by a small and otherwise indolent plasma cell (or B cell) clone secreting an unstable circulating light chain, which misfolds and deposits as amyloid fibrils possibly leading to progressive dysfunction of affected organs. AL amyloidosis can occur in the typical setting of other, rarer forms of systemic amyloidosis and can mimic other more prevalent conditions of the elderly. Therefore, its diagnosis requires a high degree of clinical suspicion and reliable diagnostic tools for accurate amyloid typing, available at specialized referral centers. In AL amyloidosis, frailty is dictated by the type and severity of organ involvement, with heart involvement being the main determinant of morbidity and mortality. Still, given a similar disease stage, elderly patients with AL amyloidosis are often an even frailer group, due to significant comorbidities, associated disability and polypharmacotherapy, socioeconomic restrictions, and limited access to clinical trials. Recent improvements in the use of biomarkers for early diagnosis, risk stratification and response monitoring, the flourishing of novel, effective anti-plasma cell therapies developed against multiple myeloma and adapted to treat AL amyloidosis, and possibly the introduction of anti-amyloid therapies are rapidly changing the clinical management of this disease and are reflected by improved outcomes. Of note, hematologic and organ responses in elderly patients with AL amyloidosis do translate in better outcome, advocating the importance of treating these patients and striving for a rapid response to therapy also in this challenging clinical setting.

Persistent reduction in global longitudinal strain in the longer term after radiation therapy in patients with breast cancer

BACKGROUND

More than 80% of breast cancer patients receive radiotherapy (RT). However, RT can lead to cardiotoxicity, which usually develops insidiously over years, making diagnosis difficult. It is also unknown whether early identification of at-risk patients might improve long-term outcome. We have previously described subclinical alterations, detected by two-dimensional speckle tracking strain echocardiography, in left ventricular (LV) function immediately following RT in breast cancer.

HYPOTHESIS

Subclinical myocardial alterations in LV function consequent to RT cardiotoxicity, observed early, persist at 12 months.

METHODS

40 chemotherapy naive women with left-sided breast cancer, treated with surgery and adjuvant breast RT, were prospectively recruited from two tertiary hospitals. Transthoracic echocardiography was performed at baseline (pre-RT), 6 weeks post-RT, and 12 months post-RT.

RESULTS

An increase in LV end diastolic and end systolic volumes was seen from baseline, consistent with persistent LV remodelling; however, due to the increase in both systolic and diastolic volumes over time, no change in LV ejection fraction (EF) was observed. Global longitudinal strain (GLS) and S' velocity remained significantly lower at 12 months post-RT. GLS dropped by >10% in 16 patients and by >20% in 4 patients compared to baseline.

CONCLUSIONS

Subclinical cardiac dysfunction using strain analysis, evident early, persists one year after RT, despite unchanged conventional indices such as LVEF. Persistent GLS reduction may be of particular importance in breast cancer patients receiving concomitant chemotherapy. Longer term prospective studies are required to determine if reductions in strain post-RT are associated with future adverse cardiovascular events.

Right ventricular involvement in transthyretin amyloidosis

BACKGROUND

The extent of right ventricular (RV) involvement in transthyretin amyloidosis (ATTR) is unknown.

OBJECTIVES

This study sought to establish the degree of RV involvement in ATTR amyloidosis, and compare findings with RV involvement in hypertrophic cardiomyopathy (HCM).

METHODS

Forty-two patients with ATTR amyloidosis and echocardiographic evidence of cardiac amyloidosis (cardiac ATTR), 19 ATTR patients with normal left ventricular (LV) wall thickness (non-cardiac ATTR), 25 patients with diagnosed HCM and 30 healthy controls were included in this study. Echocardiographic measurements for conventional parameters, as well as RV global and segmental strain, were recorded.

RESULTS

When comparing RV structure and function between cardiac ATTR amyloidosis and HCM patients, only segmental strain differed between the two groups. In cardiac ATTR amyloidosis, we found an RV apex-to-base strain gradient with highest deformation in the apex. This pattern was reversed in patients with HCM.

CONCLUSIONS

RV involvement is common in cardiac ATTR patients. The present study also detected an RV apical sparing pattern in patients with ATTR cardiomyopathy, similar to what has previously been described for the left ventricle in these patients. This pattern was not seen in HCM patients. Further studies are needed to assess the clinical importance of these findings.

Relative Apical Sparing of Myocardial Longitudinal Strain Is Explained by Regional Differences in Total Amyloid Mass Rather Than the Proportion of Amyloid Deposits

OBJECTIVES

This study sought to test whether relative apical sparing (RELAPS) of left ventricular (LV) longitudinal strain (LS) in cardiac amyloidosis (CA) is explained by regional differences in markers of amyloid burden (¹⁸F-florbetapir uptake by positron emission tomography [PET] and/or extracellular volume fraction [ECV] by cardiac magnetic resonance (CMR)].

BACKGROUND

Further knowledge of the pathophysiological basis for RELAPS can help understand the adverse outcomes associated with apical LS impairment.

METHODS

This was a prospective study of 32 subjects (age 62 ± 7 years; 50% males) with light chain CA. All subjects underwent two-dimensional echocardiography for LS estimation and ¹⁸F-florbetapir PET for quantification of LV florbetapir retention index (RI). A subset also underwent CMR (n = 22) for ECV quantification. Extracellular LV mass (LV mass*ECV) and total florbetapir binding (extracellular LV mass*florbetapir RI) were also calculated. All parameters were measured globally and regionally (base, mid, and apex).

RESULTS

There was a significant base-to-apex gradient in LS (-7.4 ± 3.2% vs. -8.6 ± 4.0% vs. -20.8 ± 6.6%; p < 0.0001), maximal LV wall thickness (15.7 ± 1.9 cm vs. 15.4 ± 2.9 cm vs. 10.1 ± 2.4 cm; p < 0.0001), and LV mass (74.8 ± 21.2 g vs. 60.8 ± 17.3 g vs. 23.4 ± 6.2 g; p < 0.0001). In contrast, florbetapir RI (0.089 ± 0.03 μmol/min/g vs. 0.097 ± 0.03 μmol/min/g vs. 0.085 ± 0.03 μmol/min/g; p = 0.45) and ECV (0.53 ± 0.08 vs. 0.49 ± 0.08 vs. 0.49 ± 0.07; p = 0.15) showed no significant base-to-apex gradient in the tissue concentration or proportion of amyloid infiltration, whereas markers of total amyloid load, such as total florbetapir binding (3.4 ± 1.7 μmol/min vs. 2.8 ± 1.5 μmol/min vs. 0.93 ± 0.49 μmol/min; p < 0.0001) and extracellular LV mass (40.0 ± 15.6 g vs. 30.2 ± 10.9 g vs. 11.6 ± 3.9 g; p < 0.0001), did show a marked base-to-apex gradient.

CONCLUSIONS

Segmental differences in the distribution of the total amyloid mass, rather than the proportion of amyloid deposits, appear to explain the marked regional differences in LS in CA. Although these 2 matrices are clearly related concepts, they should not be used interchangeably.

Longitudinal systolic strain, cardiac function improvement, and survival following treatment of light-chain (AL) cardiac amyloidosis

Aims

To determine whether echocardiographic longitudinal systolic strain (LS) parameters identify short-term improvement following chemotherapy for light-chain (AL) cardiac amyloidosis (CA). Among patients with CA, standard echocardiographic measures are commonly unchanged at 1 year following successful chemotherapy, despite observed reductions in cardiac biomarkers.

Methods and results

We retrospectively identified 61 patients with AL-CA treated with high-dose melphalan or bortezomib-based regimens. Patients were classified by hematologic response at 1 year into two groups: complete response (CR; n = 18, or 30%) or non-CR (non-CR; n = 43, or 70%), and followed for 20 months. Serum free light chains (FLC), B-type natriuretic peptide (BNP), troponin I (TnI), and echocardiography including LS, were acquired at baseline and 1 year. Seven patients died (11.5%), all in the non-CR group (P < 0.01). At 1 year, while reductions were observed in BNP (44% CR, 18% non-CR) and FLC (94% CR, 73% non-CR), both P < 0.05 from baseline, there were no differences in wall thickness, EF, or diastolic function in either group. LS improved only in the CR group with notable improvement in apical to basal strain ratio (P < 0.05). Strain improvement and BNP reduction were correlated (R = 0.6, P < 0.01). Baseline global LS < -10.2% was associated with survival and proved superior to BNP and TnI. The addition of global LS to biomarkers identified the patients at highest risk of mortality.

Conclusion

These data suggest that LS is a sensitive measure of pre-treatment cardiac functional impairment in AL-CA, can predict survival over and above that of cardiac biomarkers, and detect early cardiac functional improvement following chemotherapy.

Multimodality Imaging in Restrictive Cardiomyopathies: An EACVI expert consensus document In collaboration with the "Working Group on myocardial and pericardial diseases" of the European Society of Cardiology Endorsed by The Indian Academy of Echocardiography

Restrictive cardiomyopathies (RCMs) are a diverse group of myocardial diseases with a wide range of aetiologies, including familial, genetic and acquired diseases and ranging from very rare to relatively frequent cardiac disorders. In all these diseases, imaging techniques play a central role. Advanced imaging techniques provide important novel data on the diagnostic and prognostic assessment of RCMs. This EACVI consensus document provides comprehensive information for the appropriateness of all non-invasive imaging techniques for the diagnosis, prognostic evaluation, and management of patients with RCM.

Left atrial structure and function in cardiac amyloidosis

Aims

Although cardiac amyloidosis (CA) is characterized by significant left atrial (LA) dilatation, the characteristics of LA function remain to be fully investigated.

Methods and results

We assessed LA function by speckle-tracking echocardiography in 124 patients with CA and sinus rhythm: 68 with light chain (AL), 29 with mutant (ATTRm), 27 with wild-type (ATTRwt) transthyretin amyloidosis. Conventional and strain-derived parameters, including LA peak longitudinal strain (LS) and strain rate (peak LSR: reservoir function; early LSR: conduit function; late LSR: active function), were assessed compared between CA patients and 20 healthy controls of similar age and gender. All LA function phases, including LA longitudinal strain, peak LSR, early and late LSR were significantly impaired in CA compared to healthy controls after adjusting for LA size, LV ejection fraction and LV filling pressures (E/E') (all P < 0.05). Peak LA LS was moderately correlated with LV global LS (R = -0.60, P < 0.001); late LSR was correlated with A wave at the level of LV inflow (R = -0.69, P < 0.001). Among the different CA subtypes, peak LS and LA active emptying fraction were worse in ATTRwt than AL and ATTRm [P < 0.05 after adjustment for age, sex, body mass index, systolic blood pressure, heart rate, LA volume index, severity of mitral regurgitation, left ejection fraction, and left ventricular end-diastolic pressure (E/E')].

Conclusion

In CA, LA function was severely impaired and highly correlated with LV deformation. Differences in LA function between amyloid subtypes suggest that amyloid aetiology plays a role in the pathophysiology of cardiac dysfunction in CA.

Cardiac Structural and Functional Consequences of Amyloid Deposition by Cardiac Magnetic Resonance and Echocardiography and Their Prognostic Roles

OBJECTIVES

This cross-sectional study aimed to describe the functional and structural cardiac abnormalities that occur across a spectrum of cardiac amyloidosis burden and to identify the strongest cardiac functional and structural prognostic predictors in amyloidosis using cardiac magnetic resonance (CMR) and echocardiography.

BACKGROUND

Cardiac involvement in light chain and transthyretin amyloidosis is the main driver of prognosis and influences treatment strategies. Numerous measures of cardiac structure and function are assessed by multiple imaging modalities in amyloidosis.

METHODS

A total f 322 subjects (311 systemic amyloidosis and 11 transthyretin gene mutation carriers) underwent comprehensive CMR and transthoracic echocardiography. The probabilities of 11 commonly measured structural and functional cardiac parameters being abnormal with increasing cardiac amyloidosis burden were evaluated. Cardiac amyloidosis burden was quantified using CMR-derived extracellular volume. The prognostic capacities of these parameters to predict death in amyloidosis were assessed using Cox proportional hazards models.

RESULTS

Left ventricular mass and mitral annular plane systolic excursion by CMR along with strain and E/e' by echocardiography have high probabilities of being abnormal at low cardiac amyloid burden. Reductions in biventricular ejection fractions and elevations in biatrial areas occur at high burdens of infiltration. The probabilities of indexed stroke volume, myocardial contraction fraction, and tricuspid annular plane systolic excursion (TAPSE) being abnormal occur more gradually with increasing extracellular volume. Ninety patients (28%) died during a median follow-up of 22 months (interquartile range: 10 to 38 months). Univariable analysis showed that all imaging markers studied significantly predicted outcome. Multivariable analysis showed that TAPSE (hazard ratio: 1.46; 95% confidence interval: 1.16 to 1.85; p < 0.01) and indexed stroke volume (hazard ratio: 1.24; 95% confidence interval: 1.04 to 1.48; p < 0.05) by CMR were the only independent predictors of mortality.

CONCLUSIONS

Specific functional and structural abnormalities characterize different burdens of cardiac amyloid deposition. In a multimodality imaging assessment of a large cohort of amyloidosis patients, CMR-derived TAPSE and indexed stroke volume are the strongest prognostic cardiac functional markers.

Left Ventricular Myocardial Deformation on Cine MR Images: Relationship to Severity of Disease and Prognosis in Light-Chain Amyloidosis

Purpose To measure left ventricular (LV) myocardial strain with cine magnetic resonance (MR) imaging and a deformable registration algorithm (DRA) and to assess the prognostic value of myocardial strain in patients with light-chain (AL) amyloidosis. Materials and Methods In this prospective study, 78 consecutive patients with AL amyloidosis who underwent contrast material-enhanced cardiac MR imaging were enrolled at West China Hospital. LV myocardial strains and late gadolinium enhancement (LGE) were evaluated. Association between myocardial strain and all-cause mortality was analyzed with the stepwise Cox regression model. Results Global longitudinal strain (GLS) and global circumferential strain (GCS) were significantly lower in the no or nonspecific LGE group compared with the subendocardial LGE and transmural LGE groups (mean GLS, -10% ± 3 [standard deviation] vs -7% ± 3 vs -4% ± 1; P < .001) (mean GCS, -13% ± 3 vs -11% ± 3 vs -7% ± 2; P < .001). GLS and GCS were reduced in patients without clinical cardiac amyloidosis (mean GLS, -13% ± 3 vs -16% ± 2; P = .005) (mean GCS, -16% ± 1 vs -19% ± 2; P = .02). Circumferential and radial strains were impaired in basal segments in accordance with the distribution of LGE. Multivariate Cox analysis revealed that GCS (hazard ratio [HR] = 1.16 per 1% absolute decrease; 95% confidence interval [CI]: 1.03, 1.31; P = .02) and the presence of transmural LGE (HR = 1.75; 95% CI: 1.10, 2.80; P = .02) were independent predictors of all-cause mortality after adjustment for LV ejection fraction, right ventricular ejection fraction, LV mass index, GLS, and global radial strain. Conclusion Strain parameters derived with cine MR imaging-based DRA may be a new noninvasive imaging marker with which to evaluate the extent of cardiac amyloid infiltration and may offer independent prognostic information for all-cause mortality in patients with AL amyloidosis.

Recent advances in the noninvasive strategies of cardiac amyloidosis

The heart, like any organ in the body, is susceptible to amyloid deposition. Although more than 30 types of protein can cause amyloidosis, only two types commonly deposit in the ventricular myocardium: amyloid light chain and amyloid transthyretin. Amyloid cardiomyopathy is usually a major determinant of patient outcomes, and the diagnosis of heart involvement can be often relatively under-diagnosed, owing to nonspecific presenting symptoms and signs at a subclinical stage. The diagnosis of cardiac amyloidosis is usually performed by endomyocardial biopsy; however, the invasive nature and related high-risk complications restrict its wide use in clinical settings. Recently, with the advent of innovative techniques used for evaluating cardiac amyloidosis, noninvasive methods become increasingly important, especially in earlier diagnosis, distinguishing typing, risk prediction and response to treatment. Here, we will review recent developments in the noninvasive methods used in the assessment of cardiac amyloidosis, focused on the laboratory biomarkers and imaging modalities.

Abnormal Coronary Flow Velocity Reserve and Decreased Myocardial Contractile Reserve Are Main Factors in Relation to Physical Exercise Capacity in Cardiac Amyloidosis

BACKGROUND

The aim of the present study was to evaluate the clinical importance of echocardiographic coronary flow velocity reserve (CFVR), resting and exercise left ventricular global longitudinal strain (LVGLS), and myocardial work efficiency (MWE) in patients with cardiac amyloidosis (CA).

METHODS

The study population comprised 69 subjects: group A, 27 patients with CA confirmed by endomyocardial biopsy (CA positive); group B, 42 healthy control subjects. The amyloid phenotype in group A was as follows: patients with wild-type transthyretin-related amyloidosis (n = 10), carriers of the Danish familial transthyretin amyloidosis mutation with cardiac involvement (n = 5), and patients with amyloid light chain amyloidosis with cardiac involvement (n = 12). All subjects underwent comprehensive echocardiographic evaluation during rest and during symptom-limited, semisupine exercise testing. Furthermore, CFVR was assessed using Doppler echocardiography.

RESULTS

Patients with CA had significantly lower CFVR (1.7 ± 0.6 vs 3.9 ± 0.8, P < .0001), MWE (1.9 ± 1.0 vs 3.0 ± 0.7, P < .0001), and LVGLS magnitude (11% [10%-14%] vs 20% [18%-21%], P < .0001) than control subjects. Patients with CA showed severely reduced deformation and efficiency reserve compared with control subjects (ΔLVGLS 0.9 ± 2.8% vs 5.6 ± 2.3%, P < .0001; ΔMWE 2.5 ± 2.8 vs 8.8 ± 2.6, P < .0001). In patients with CA, a strong relation was seen between physical capacity by the metabolic equivalent of tasks test and CFVR (r = 0.55, P < .01), peak exercise LVGLS (r = 0.64, P < .0001), and peak exercise MWE (r = 0.60, P < .01).

CONCLUSIONS

Patients with CA had a profound lack of CFVR and longitudinal myocardial deformation reserve compared with healthy control subjects. Both parameters were significantly associated with exercise capacity and may prove useful for evaluating cardiac performance in patients with CA.

Recent Advances in Cardiovascular Imaging Relevant to the Management of Patients with Suspected Cardiac Amyloidosis

Cardiac amyloidosis is a form of infiltrative cardiomyopathy typically presenting with progressive heart failure. The clinical presentation and morphological findings often overlap with other cardiovascular diseases, and frequently results in misdiagnosis and consequent under-reporting. Cardiovascular imaging is playing an increasingly important diagnostic and prognostic role in this referral population, and is reducing the reliance on endomyocardial biopsy as a confirmatory testing. Advancements across multiple cardiac imaging modalities, including echocardiography, magnetic resonance imaging, nuclear imaging, and computed tomography, are improving diagnostic accuracy and offering novel approaches to sub-type differentiation and prognostication. This review explores recent advancements in cardiac imaging for the diagnosis, typing, and staging of cardiac amyloidosis, with a focus on new and evolving techniques. Emphasis is also placed on the promise of non-invasive cardiac imaging to provide value across the spectrum of this clinical disease, from early disease identification (prior to the development of increased wall thickness) through to markers of advanced disease associated with early mortality.

Unveiling transthyretin cardiac amyloidosis and its predictors among elderly patients with severe aortic stenosis undergoing transcatheter aortic valve replacement

AIMS

Transthyretin cardiac amyloidosis (ATTR-CA) has been reported in patients with aortic stenosis (AS) but its prevalence and phenotype are not known. We examine elderly patients with severe symptomatic AS undergoing transcatheter aortic valve replacement (TAVR) and determine the prevalence and phenotype of ATTR-CA non-invasively.

METHODS AND RESULTS

We performed technetium-99m pyrophosphate (99mTc-PYP) cardiac scintigraphy prospectively on patients who underwent TAVR, to screen for ATTR-CA. Transthoracic echocardiography and speckle-strain imaging were performed. We assessed the association of several parameters with ATTR-CA using multivariable logistic regression and constructed receiver operating curves to evaluate the best predictors of ATTR-CA. Among 151 patients (mean age 84 ± 6 years, 68% men), 16% (n = 24) screened positive for ATTR-CA with 99mTc-PYP scintigraphy. Compared with patients without ATTR-CA, ATTR-CA patients had a thicker interventricular septum (1.3 vs. 1.1 cm, P = 0.007), higher left ventricular (LV) mass index (130 vs. 98 g/m2, P = 0.002), and lower stroke volume index (30 vs. 36 mL/m2, P = 0.009). ATTR-CA patients had advanced diastolic dysfunction with higher E/A ratio (2.3 vs. 0.9, P = 0.001) and lower deceleration time (176 vs. 257 ms, P < 0.0001); impairment in systolic function with lower ejection fraction (48% vs. 56%, P = 0.011), myocardial contraction fraction (26 vs. 41, P < 0.0001), and average of lateral and septal mitral annular tissue Doppler S' (4.0 vs. 6.6 cm/s, P < 0.0001). While ATTR-CA patients had more impaired global longitudinal strain (-12 vs. -16%, P = 0.007), relative apical longitudinal strain was the same regardless of ATTR-CA diagnosis (0.98 vs. 0.98, P = 0.991). Average S' best predicted ATTR-CA in multivariable logistic regression (odds ratio 16.67 per 1 cm/s decrease with AUC 0.96, 95% confidence interval 0.90-0.99, P = 0.002) with a value ≤6 conferring 100% sensitivity for predicting a positive 99mTc-PYP amyloid scan.

CONCLUSIONS

Transthyretin cardiac amyloidosis is prevalent in 16% of patients with severe calcific AS undergoing TAVR and is associated with a severe AS phenotype of low-flow low-gradient with mildly reduced ejection fraction. Average tissue Doppler mitral annular S' of < 6 cm/s may be a sensitive measure that should prompt a confirmatory 99mTc-PYP scan and subsequent testing for ATTR-CA. Prospective assessment of outcomes after TAVR is needed in patients with and without ATTR-CA.

Restrictive Cardiomyopathy

Restrictive cardiomyopathy (RCM) is characterized by nondilated left or right ventricle with diastolic dysfunction. The restrictive cardiomyopathies are a heterogenous group of myocardial diseases that vary according to pathogenesis, clinical presentation, diagnostic evaluation and criteria, treatment, and prognosis. In this review, an overview of RCMs will be presented followed by a detailed discussion on 3 major causes of RCM, for which tailored interventions are available: cardiac amyloidosis, cardiac sarcoidosis, and cardiac hemochromatosis. Each of these 3 RCMs is challenging to diagnose, and recognition of each disease entity is frequently delayed. Clinical clues to promote recognition of cardiac amyloidosis, cardiac sarcoidosis, and cardiac hemochromatosis and imaging techniques used to facilitate diagnosis are discussed. Disease-specific therapies are reviewed. Early recognition remains a key barrier to improving survival in all RCMs.

Diagnosis and Treatment of Transthyretin Cardiac Amyloidosis. Progress and Hope

Cardiac amyloidosis is an infiltrative disorder caused by extracellular protein deposition. Transthyretin is a proamyloidotic protein that produces one of the most frequent forms of cardiac amyloidosis, either through mutations or a wild-type form (previously known as senile amyloidosis). Until very recently, diagnosis of transthyretin amyloidosis (ATTR) was very uncommon and histological confirmation was mandatory, making diagnosis of ATTR a real challenge in daily clinical practice. Moreover, the specific therapeutic options to alter the clinical course of the disease were very limited. However, advances in cardiac imaging and diagnostic strategies have improved recognition of ATTR. In addition, several compounds able to modify the natural history of the disease are in the final phases of research, with promising results. Given that effective therapies are on the horizon, cardiologists should be well-versed in this disease and be familiar with its diagnosis and treatment. This review describes the broad clinical spectrum of ATTR in detail, as well as recent advances in the diagnosis and treatment of this condition.

Current Concepts of Cardiac Amyloidosis: Diagnosis, Clinical Management, and the Need for Collaboration

Cardiac amyloidosis is a complex and vexing clinical condition that requires a high degree of suspicion for the diagnosis with a substantial amount of discipline to discern the extent of disease and the best available therapy. There is a complex interplay between multiple organ systems, and the clinical presentation may involve a myriad of confusing clinical symptoms. The diagnosis of cardiac amyloidosis can be confirmed with a combination of physical findings, cardiac biomarkers, noninvasive testing, and, if necessary, myocardial biopsy. Genetic testing is critical to establish the type of amyloidosis.

Transthyretin Cardiac Amyloidosis

PURPOSE OF REVIEW

Transthyretin (TTR)-related cardiac amyloidosis is a progressive infiltrative cardiomyopathy that mimics hypertensive, hypertrophic heart disease and may go undiagnosed. Transthyretin-derived amyloidosis accounts for 18% of all cases of cardiac amyloidosis. Thus, the study's purpose is to provide a comprehensive review of transthyretin cardiac amyloidosis.

RECENT FINDINGS

Wild-type transthyretin (ATTRwt) protein causes cardiac amyloidosis sporadically, with 25 to 36% of the population older than 80 years of age are at risk to develop a slowly progressive, infiltrative amyloid cardiomyopathy secondary to ATTRwt. In contrast, hereditary amyloidosis (ATTRm) is an autosomal dominant inherited disease associated with more than 100 point mutations in the transthyretin gene and has a tendency to affect the heart and nervous system. Up to 4% of African-Americans carry the Val122Ile mutation in the transthyretin gene, the most prevalent cause of hereditary cardiac amyloidosis in the USA. Identifying transthyretin cardiac amyloidosis requires increased awareness of the prevalence, signs and symptoms, and diagnostic tools available for discrimination of this progressive form of cardiomyopathy associated with left ventricular hypertrophy. While there are no FDA-approved medical treatments, investigation is underway on agents to reduce circulating mutated transthyretin.

Histological and Histometric Characterization of Myocardial Fibrosis in End-Stage Hypertrophic Cardiomyopathy: A Clinical-Pathological Study of 30 Explanted Hearts

BACKGROUND

Although noninvasively detected myocardial fibrosis (MF) has clinical implications in hypertrophic cardiomyopathy, the extent, type, and distribution of ventricular MF have never been extensively pathologically characterized. We assessed the overall amount, apex-to-base, circumferential, epicardial-endocardial distribution, pattern, and type of MF in 30 transplanted hearts of end-stage, hypertrophic cardiomyopathy.

METHODS AND RESULTS

Visual and morphometric histological analyses at basal, midventricular, and apical levels were performed. Overall MF ranged from 23.1% to 55.9% (mean=37.3±8.4%). Prevalent types of MF were as follows: replacement in 53.3%, interstitial-perimyocyte in 13.3%, and mixed in 33.3%. Considering left ventricular base-to-apex distribution, MF was 31.9%, 43%, and 46.2% at basal, midventricular, and apical level, respectively (P<0.001). Circumferential distributions (mean percentage of MF within the section) were as follows: anterior 11.9%, anterolateral 15.8%, inferolateral 7.0%, inferior 24.3%, anteroseptal 11%, midseptal 10.7%, and posteroseptal 11.4%; circumferential distributions for anterior and inferior right ventricular walls were 3.4% and 4.5%, respectively. Epicardial-endocardial distributions were as follows: trabecular 26.1% and subendocardial 20.2%, midwall 33.4%, and subepicardial 20.3%. Main patterns identified were as follows: midwall in 33.3% of the hearts, transmural in 23.3%, midwall-subepicardial in 23.3%, and midwall-subendocardial in 20%.

CONCLUSIONS

In end-stage, hypertrophic cardiomyopathy patients undergoing transplantation, more than one-third of the left ventricular myocardium was replaced by fibrosis, mainly of replacement type. MF preferentially involved the left ventricular apex and the midwall. Inferior and anterior walls and septum were maximally involved, whereas inferolateral and right ventricular were usually spared. These observations reflect the complex pathophysiology of hypertrophic cardiomyopathy and may provide clues for the timely recognition of disease progression by imaging techniques capable of quantifying MF.

Transthyretin Cardiac Amyloidosis in Black Americans

Transthyretin-related cardiac amyloidosis is a progressive infiltrative cardiomyopathy that mimics hypertensive and hypertrophic heart disease and often goes undiagnosed. In the United States, the hereditary form disproportionately afflicts black Americans, who when compared with whites with wild-type transthyretin amyloidosis, a phenotypically similar condition, present with more advanced disease despite having a noninvasive method for early identification (genetic testing). Although reasons for this are unclear, this begs to consider the inadequate access to care, societal factors, or a biological basis. In an effort to improve awareness and explore unique characteristics, we review the pathophysiology, epidemiology, and therapeutic strategies for transthyretin amyloidosis and highlight diagnostic pitfalls and clinical pearls for identifying patients with amyloid heart disease.

Aβ Amyloid Pathology Affects the Hearts of Patients With Alzheimer's Disease: Mind the Heart

BACKGROUND

Individually, heart failure (HF) and Alzheimer's disease (AD) are severe threats to population health, and their potential coexistence is an alarming prospect. In addition to sharing analogous epidemiological and genetic profiles, biochemical characteristics, and common triggers, the authors recently recognized common molecular and pathological features between the 2 conditions. Whereas cognitive impairment has been linked to HF through perfusion defects, angiopathy, and inflammation, whether patients with AD present with myocardial dysfunction, and if the 2 conditions bear a common pathogenesis as neglected siblings are unknown.

OBJECTIVES

Here, the authors investigated whether amyloid beta (Aβ) protein aggregates are present in the hearts of patients with a primary diagnosis of AD, affecting myocardial function.

METHODS

The authors examined myocardial function in a retrospective cross-sectional study from a cohort of AD patients and age-matched controls. Imaging and proteomics approaches were used to identify and quantify Aβ deposits in AD heart and brain specimens compared with controls. Cell shortening and calcium transients were measured on isolated adult cardiomyocytes.

RESULTS

Echocardiographic measurements of myocardial function suggest that patients with AD present with an anticipated diastolic dysfunction. As in the brain, Aβ₄₀ and Aβ₄₂ are present in the heart, and their expression is increased in AD.

CONCLUSIONS

Here, the authors provide the first report of the presence of compromised myocardial function and intramyocardial deposits of Aβ in AD patients. The findings depict a novel biological framework in which AD may be viewed either as a systemic disease or as a metastatic disorder leading to heart, and possibly multiorgan failure. AD and HF are both debilitating and life-threatening conditions, affecting enormous patient populations. Our findings underline a previously dismissed problem of a magnitude that will require new diagnostic approaches and treatments for brain and heart disease, and their combination.

Diagnostic score for the detection of cardiac amyloidosis in patients with left ventricular hypertrophy and impact on prognosis

BACKGROUND

Among diagnosis associated with left ventricular hypertrophy (LVH), cardiac amyloidosis (CA) is a progressive disease with poor prognosis. Early noninvasive identification is of growing clinical importance. The objective of our study was to integrate clinical, biologic, electrocardiographic and echocardiographic parameters to build a diagnostic score in patients with LVH.

METHODS AND RESULTS

One hundred and fourteen patients with LVH underwent a cardiac magnetic resonance (CMR) and a ^99mTc-hydroxymethylene-diphosphonate scintigraphy (^99mTc-HMDP) allowing to discriminate three groups of diagnoses: CA (n = 50 including 31, 18 and 1 ATTR, AL and AA amyloidosis), hypertrophic cardiomyopathy (n = 19) and unspecific cardiomyopathy (n = 45). Seven continuous variables associated with CA (systolic arterial pressure <130 mmHg; PR duration >200 ms; Sokolow index <12 mV; diastolic left ventricular posterior thickness >13 mm; E/Ea ratio >10; global longitudinal strain > -12% and sum of basal longitudinal strain > -47%) were selected and dichotomized according to the best cutoff value to build the diagnostic score, which was validated in an independent cohort of 34 patients with LVH from aortic stenosis. The area under the ROC curve for the diagnosis of CA using the score was 0.933 (95%CI 0.889-0.978). The best cut off value for the score was 3 leading to a sensitivity of 90% and specificity of 81%. Area under the ROC curve for the score was 0.932 in the validation cohort. A diagnostic score >3 was associated with a poorest prognosis.

CONCLUSION

An integrated evaluation of 6 diagnostic factors including arterial blood pressure, ECG and echocardiographic parameters to build a diagnostic score is a simple and easily method to discriminate the 3 main CA in patients with LVH.

Transthyretin Cardiac Amyloidosis in Older Adults: Optimizing Cardiac Imaging to the Corresponding Diagnostic and Management Goal

PURPOSE OF REVIEW

Transthyretin cardiac amyloidosis is increasingly recognized as an important cause of heart failure in older adults. Many cardiac imaging modalities have evolved to evaluate transthyretin cardiac amyloidosis and include 2D echocardiography with tissue Doppler and speckle-strain imaging, nuclear scintigraphy, cardiac magnetic resonance imaging, and positron emission tomography. The purpose of this review is to highlight the optimal selection of advanced cardiac imaging techniques with corresponding diagnostic goals including raising suspicion, making an early diagnosis, and subtyping transthyretin cardiac amyloid, as well as management goals including assessment of ventricular impairment, prognosticating, and monitoring disease progression. Potential benefits of optimizing cardiac imaging in the elderly patient with transthyretin cardiac amyloidosis may include enhanced and earlier diagnosis and refined long-term management.

RECENT FINDINGS

Advances in cardiac imaging techniques are changing diagnostic and management algorithms for transthyretin cardiac amyloidosis.

SUMMARY

With a new era of novel therapeutics, enhanced recognition, and earlier diagnosis approaching, selecting the appropriate non-invasive cardiac imaging modality will be essential for optimal care in the elderly patient with transthyretin cardiac amyloidosis.

Echo Parameters for Differential Diagnosis in Cardiac Amyloidosis: A Head-to-Head Comparison of Deformation and Nondeformation Parameters

BACKGROUND

A plethora of echo parameters has been suggested for distinguishing cardiac amyloidosis (CA) from other causes of myocardial thickening with, however, scarce data on their head-to-head comparison. This study aimed at comparing the diagnostic accuracy of various deformation and conventional echo parameters in differentiating CA from other hypertrophic substrates, especially in the gray zone of mild hypertrophy (maximum wall thickness ≤16 mm) or normal ejection fraction (EF).

METHODS AND RESULTS

=0.0002, respectively) independent of the CA type.

CONCLUSIONS

Our study demonstrated that in patients with thickened hearts, EF global longitudinal strain ratio has the best accuracy in detecting CA, even among the most "challenging" patient subgroups as those with mild hypertrophy and normal EF.

Addressing Common Questions Encountered in the Diagnosis and Management of Cardiac Amyloidosis

Advances in cardiac imaging have resulted in greater recognition of cardiac amyloidosis in everyday clinical practice, but the diagnosis continues to be made in patients with late-stage disease, suggesting that more needs to be done to improve awareness of its clinical manifestations and the potential of therapeutic intervention to improve prognosis. Light chain cardiac amyloidosis, in particular, if recognized early and treated with targeted plasma cell therapy, can be managed very effectively. For patients with transthyretin amyloidosis, there are numerous therapies that are currently in late-phase clinical trials. In this review, we address common questions encountered in clinical practice regarding etiology, clinical presentation, diagnosis, and management of cardiac amyloidosis, focusing on recent important developments in cardiac imaging and biochemical diagnosis. The aim is to show how a systematic approach to the evaluation of suspected cardiac amyloidosis can impact the prognosis of patients in the modern era.

Left Ventricle Relative Apical Sparing in Cardiac Amyloidosis

Amyloidosis is a disease characterized by the extracellular deposition of the protein amyloid. It is a multiorgan disease, and cardiac involvement is not uncommon, generally in the form of a restrictive cardiomyopathy. Typical aspects of cardiac amyloidosis have been described at echocardiography and magnetic resonance imaging (MRI). In particular, the relative apical sparing at two-dimensional speckle-tracking echocardiography has been reported to be specific for cardiac amyloidosis. In our case, we report for the first time that this echocardiographic sign is related to lack of hyperenhancement at late gadolinium enhancement imaging in cardiac MRI.

Transthyretin Cardiac Amyloidosis in Older Americans

Wild-type transthyretin cardiac amyloidosis (ATTRwt), formerly called senile cardiac amyloidosis (SCA), is almost exclusively a disorder of older adults. As the population ages, the diagnosis of ATTRwt will increase, making it the most common form of cardiac amyloidosis. An important precondition to reduce underdiagnosis and misdiagnosis is to maintain a high index of suspicion for cardiac amyloidosis. Several clues can be gleaned from the clinical history, physical exam, electrocardiography, and noninvasive imaging techniques. Nuclear scintigraphy agents using 99mTc-phosphate derivatives combined with assessment for monoclonal proteins are eliminating the need for tissue confirmation in ATTR. Morbidity and mortality from ATTRwt cardiac amyloid is high and the emergence of numerous therapies based on a biologic understanding of the pathophysiology of this condition, including drugs to inhibit the synthesis of TTR, stabilize TTR, and degrade or extract amyloid, provides new hope for those afflicted. This review briefly covers the epidemiology, pathophysiology, and clinical manifestations, as well as diagnostic strategies and treatment, of ATTR in older adults.

Tissue Tracking Technology for Assessing Cardiac Mechanics: Principles, Normal Values, and Clinical Applications

Tissue tracking technologies such as speckle tracking echocardiography and feature tracking cardiac magnetic resonance have enhanced the noninvasive assessment of myocardial deformation in clinical research and clinical practice. The widespread enthusiasm for using tissue tracking techniques in research and clinical practice stems from the ready applicability of these technologies to routine echocardiographic or cardiac magnetic resonance images. The technology is common to both modalities, and derived parameters to describe myocardial mechanics are the similar, albeit with different accuracies. We provide an overview of the normal values and reproducibility of the clinically applicable parameters, together with their clinical validation. The use of these technologies in different clinical scenarios, and the additive value to current imaging diagnostics are discussed.

Prognosis of Light Chain Amyloidosis With Preserved LVEF: Added Value of 2D Speckle-Tracking Echocardiography to the Current Prognostic Staging System

OBJECTIVES

This study evaluated whether 2-dimensional speckle-tracking echocardiography (2D-STE) has incremental value for prognosis over traditional clinical, echocardiographic, and serological markers-with main focus on the current prognostic staging system-in light-chain (AL) amyloidosis patients with preserved left ventricular ejection fraction.

BACKGROUND

Cardiac amyloidosis (CA) is the major determinant of outcome in AL amyloidosis. The current prognostic staging system is based primarily on serum levels of cardiac troponin T (cTnT), N-terminal pro-B-type natriuretic peptide (NT-proBNP), and free light chain differential (FLC-diff).

METHODS

Consecutive patients with biopsy-proven AL amyloidosis and left ventricular ejection fraction ≥55% were divided into group 1 with CA (n = 63) and group 2 without CA (n = 87). Global longitudinal strain (GLS) by 2D-STE was performed with Vivid E9 (GE Healthcare Co., Milwaukee, Wisconsin) and syngo Velocity Vector Imaging (VVI) software (Siemens Medical Solutions USA, Inc., Malvern, Pennsylvania) (GLS_GE and GLS_VVI, respectively).

RESULTS

Thirty-two deaths (51%) occurred in group 1 and 13 (15%) in group 2 (p ≤ 0.001). Group 1 had thicker walls, lower early diastolic tissue Doppler velocity at septal mitral annulus, and greater left ventricular mass, left atrial volume, glomerular filtration rate, FLC-diff, cTnT, and NT-proBNP (p < 0.001). For the entire cohort, GLS_GE ≥ -14.81, GLS_VVI ≥-15.02, cTnT, NT-proBNP, FLC-diff, age, left ventricular wall thickness, early diastolic tissue Doppler velocity at septal mitral annulus, diastolic dysfunction grade, glomerular filtration rate, deceleration time, and left atrial volume were univariate predictors of death. In a multivariate Cox model, GLS_GE ≥-14.81 (hazard ratio [HR]: 2.68; 95% confidence interval [CI]: 1.07 to 7.13; p = 0.03), FLC-diff, NT-proBNP, and age were independent predictors of survival. There was also a strong trend for GLS_VVI ≥-15.02 (HR: 2.44; 95% CI: 0.98 to 6.33; p = 0.055). Using a nested logistic regression model, GLS_GE (p = 0.03) and GLS_VVI (p = 0.05) provided incremental prognostic value over cTnT, NT-proBNP, and FLC-diff. For survival analysis limited to group 2 (non-CA), GLS_GE and GLS_VVI both predicted all-cause mortality (GLS_GE HR: 1.23; 95% CI: 1.03 to 1.47 [p = 0.02]; GLS_VVI HR: 1.22; 95% CI: 1.01 to 1.49 [p = 0.04], respectively).

CONCLUSIONS

2D-STE predicted outcome and provided incremental prognostic information over the current prognostic staging system, especially in the group without CA.