Echocardiographic features of primary, secondary and familial amyloidosis

Amyloid Heart Disease

Cardiac amyloidosis is a group of disorders that develop secondary to the deposition of misfolded proteins in the heart. It can occur in isolation or as part of a systemic disease and can be inherited or acquired. Amyloid light chain (AL) and amyloid transthyretin (ATTR) are the two main forms of amyloid proteins that can infiltrate the heart. With the increased use of advanced imaging techniques and protocols, the recognition and diagnosis of cardiac amyloidosis, especially ATTR, has become easier. New therapies intended to improve survival and quality of life in patients with cardiac amyloidosis are emerging. This article provides an up-to-date review of cardiac amyloidosis.

Cardiac amyloidosis: approaches to diagnosis and management

Amyloidosis is a clinical disorder caused by the extracellular deposition of misfolded, insoluble aggregated protein with a characteristic ss pleated sheet configuration that produces apple-green birefringence under polarized light when stained with Congo red dye. The spectrum of organ involvement can include the kidneys, heart, blood vessels, central and peripheral nervous systems, liver, intestines, lungs, eyes, skin, and bones. Cardiovascular amyloidosis can be primary, a part of systemic amyloidosis, or the result of chronic systemic disease elsewhere in the body. The most common presentations are congestive heart failure because of restrictive cardiomyopathy and conduction abnormalities. Recent developments in imaging techniques and extracardiac tissue sampling have minimized the need for invasive endomyocardial biopsy for amyloidosis. Cardiac amyloidosis management will vary depending on the subtype but consists of supportive treatment of cardiac related symptoms and reducing the amyloid fibrils formation attacking the underlying disease. Despite advances in treatment, the prognosis for patients with amyloidosis is still poor and depends on the underlying disease type. Early diagnosis of cardiac amyloidosis may improve outcomes but requires heightened suspicion and a systematic clinical approach to evaluation. Delays in diagnosis, uncertainties about the relative merits of available therapies, and difficulties in mounting large-scale clinical trials in rare disorders combine to keep cardiac amyloidosis a challenging problem. This review outlines current approaches to diagnosis, assessment of disease severity, and treatment of cardiac amyloidosis.

Cardiovascular magnetic resonance and prognosis in cardiac amyloidosis

BACKGROUND

Cardiac involvement is common in amyloidosis and associated with a variably adverse outcome. We have previously shown that cardiovascular magnetic resonance (CMR) can assess deposition of amyloid protein in the myocardial interstitium. In this study we assessed the prognostic value of late gadolinium enhancement (LGE) and gadolinium kinetics in cardiac amyloidosis in a prospective longitudinal study.

MATERIALS AND METHODS

The pre-defined study end point was all-cause mortality. We prospectively followed a cohort of 29 patients with proven cardiac amyloidosis. All patients underwent biopsy, 2D-echocardiography and Doppler studies, 123I-SAP scintigraphy, serum NT pro BNP assay, and CMR with a T1 mapping method and late gadolinium enhancement (LGE).

RESULTS

Patients with were followed for a median of 623 days (IQ range 221, 1436), during which 17 (58%) patients died. The presence of myocardial LGE by itself was not a significant predictor of mortality. However, death was predicted by gadolinium kinetics, with the 2 minute post-gadolinium intramyocardial T1 difference between subepicardium and subendocardium predicting mortality with 85% accuracy at a threshold value of 23 ms (the lower the difference the worse the prognosis). Intramyocardial T1 gradient was a better predictor of survival than FLC response to chemotherapy (Kaplan Meier analysis P = 0.049) or diastolic function (Kaplan-Meier analysis P = 0.205).

CONCLUSION

In cardiac amyloidosis, CMR provides unique information relating to risk of mortality based on gadolinium kinetics which reflects the severity of the cardiac amyloid burden.

Evaluation and management of the cardiac amyloidosis

Cardiac amyloidosis describes clinically significant involvement of the heart by amyloid deposition, which may or may not be associated with involvement of other organs. The purpose of this review is to summarize the current state of evidence for the effective evaluation and management of cardiac amyloidosis. Acquired systemic amyloidosis occurs in more than 10 per million person-years in the U.S. population. Although no single noninvasive test or abnormality is pathognomonic of cardiac amyloid, case-control studies indicate that echocardiographic evidence of left ventricular wall thickening, biatrial enlargement, and increased echogenicity in conjunction with reduced electrocardiographic voltages is strongly suggestive of cardiac amyloidosis. Furthermore, newer echocardiographic techniques such as strain and strain rate imaging can demonstrate impairment in longitudinal function before ejection fraction becomes abnormal. Recent observational studies also suggest that cardiovascular magnetic resonance imaging yields characteristic findings in amyloidosis, offering promise for the early detection of cardiac involvement, and the presence of detectable cardiac troponin and elevated B-type natriuretic peptide in serum of affected patients portends an adverse prognosis. Management strategies for cardiac amyloid are largely based on nonrandomized single-center studies. One of the few published randomized studies shows the superiority of oral prednisolone and melphalan compared with colchicine in systemic AL amyloidosis. Intermediate-dose infusional chemotherapy regimes (such as vincristine, adriamycin, and dexamethasone) and high-dose chemotherapy with peripheral stem cell rescue have been used widely, but treatment-related mortality remains substantial with chemotherapy. Recent studies also indicate promising strategies to stabilize the native structures of amyloidogenic proteins; inhibit fibril formation; and disrupt established deposits using antibodies, synthetic peptides, and small-molecule drugs.

Detection of left ventricular systolic dysfunction in cardiac amyloidosis with strain rate echocardiography

BACKGROUND

We examined the potential role of Doppler myocardial imaging including tissue velocity imaging, strain imaging, and strain rate imaging for detection of left ventricular systolic dysfunction in cardiac amyloidosis (CA) and determined the minimum dataset required to make the diagnosis.

METHODS AND RESULTS

Doppler myocardial imaging was performed in 103 patients with amyloidosis (AL). Peak longitudinal systolic tissue velocity, systolic strain rate (sSR), and systolic strain (sS) were determined for 16 left ventricular segments. Radial and circumferential sSR and sS were also measured. Patients with increased left ventricular wall thickness were classified with advanced-CA, and the remainder of the patients were classified with AL-normal-wall-thickness. The global means of peak systolic tissue velocity (3.6 +/- 1.0 vs. 3.9 +/- 0.9, P = .007), sSR (-0.8 +/- 0.3 vs. -1.0 +/- 0.2, P < .001), and sS (-9.9 +/- 3.7 vs. -15.6 +/- 3.3, P < .001) were significantly lower in advanced-CA compared with AL-normal-wall-thickness. The mean of either sSR or sS from 6 middle or all 16 segments similarly differentiated patients with advanced-CA from AL-normal-wall-thickness.

CONCLUSIONS

Longitudinal sS most accurately detects longitudinal systolic dysfunction in AL and best differentiates patients with advanced-CA with increased ventricular thickness from patients with AL-normal-wall-thickness. Interrogation of six middle segments was sufficient in identifying patients with advanced-CA. Further studies are warranted to define the incremental prognostic value of these new parameters in predicting outcomes for patients with AL.

Regionally heterogeneous tissue mechanics in cardiac amyloidosis

OBJECTIVE

The goal of this study was to examine in vitro tissue stiffness and contractile performance in myocardial amyloidosis.

BACKGROUND

Primary systemic amyloidosis involves the deposition of amyloid protein in mesodermal tissues including the heart. Functional assessment of cardiac amyloidosis is usually performed using echocardiography. However, this technique does not involve assessment of preload-dependent contractile reserve (the Frank-Starling mechanism).

METHODS

At the time of heart transplantation, isolated myocardial trabeculae were dissected from the right ventricle of a patient with primary systemic amyloidosis. In vitro length-tension experiments were performed and trabeculae were subsequently fixed, sectioned and stained with crystal violet to determine amyloid deposition.

RESULTS

Among the nine trabeculae capable of generating force transients, various combinations of myocardial stiffness and contractile performance were observed including normal stiffness and contractility, severely increased stiffness with impaired contractility and hybrid patterns. Histological analysis demonstrated varying degrees of amyloid deposition among sampled trabeculae.

CONCLUSIONS

Our findings extend previous reports of functional heterogeneity among patients by demonstrating functional heterogeneity within a single patient's heart. Our findings also highlight the functional interdependence of passive stiffness and systolic performance in the diseased myocardium and demonstrate the value of dynamic assessments of myocardial performance.

Obstructive intramural coronary amyloidosis and myocardial ischemia are common in primary amyloidosis

PURPOSE

The purpose of this study was to determine the prevalence of clinical syndromes and pathologic changes of myocardial ischemia due to obstructive intramural coronary amyloidosis among patients with primary amyloidosis and cardiac involvement.

SUBJECTS AND METHODS

Medical records and pathologic specimens were reviewed from 96 patients with primary amyloidosis and cardiac involvement at autopsy or after cardiac transplantation during a 20-year period. Medical records were reviewed for patient demographic and clinical characteristics, including evidence for syndromes of myocardial ischemia. Pathologic specimens were examined for obstructive intramural coronary amyloidosis and microscopic changes of myocardial ischemia.

RESULTS

Obstructive intramural coronary amyloidosis was present in 63 of 96 patients (66%). Microscopic changes of myocardial ischemia were more common in patients with obstructive intramural coronary amyloidosis (86%) than in those without (52%) (P <.001). In the 76 patients without coexistent severe epicardial coronary atherosclerosis, changes of myocardial ischemia were more common in those with obstructive intramural coronary amyloidosis (83%) than in those without (45%) (P <.001). In patients who had tissue available for review, none had obstruction of epicardial coronary arteries from amyloid. Syndromes of myocardial ischemia affected 16 patients (25%) with obstructive intramural coronary amyloidosis but only 2 patients (6%) without (P=.027). For 11% of the patients with obstructive intramural coronary amyloidosis, a syndrome of myocardial ischemia consisting of acute myocardial infarction or angina pectoris was the first manifestation of primary amyloidosis.

CONCLUSION

Most patients with primary systemic amyloidosis and cardiac involvement have obstructive intramural coronary amyloidosis and associated microscopic changes of myocardial ischemia. Syndromes of myocardial ischemia may occur in these patients.

Doppler tissue imaging of the heart in secondary amyloidosis

Secondary amyloidosis (SA) affects cardiac texture and function by interstitial fibrosis. Doppler tissue imaging (DTI) may quantify heart function through the assessment of myocardial velocities. Echocardiographic findings of early cardiac amyloidosis (CA) without heart failure (HF) caused by SA were determined both by standard methods and DTI. It was then determined whether DTI is superior to conventional echocardiography in documenting early CA due to SA. Twenty-five patients with SA who had CA without HF (group 1) were compared with 25 healthy control subjects (group 2). After standard echocardiography, systolic (s), early (e) and late diastolic (a) velocities of interventricular septum, anterolateral, and anterior and inferior walls were measured from mitral annulus by DTI. The averages were called (s(mean)), (e(mean)), and (a(mean)), respectively. Fractional shortening (FS) and ejection fraction (EF) values of groups 1 and 2 were similar. Standard Doppler echocardiographic values were not typical for a specific diastolic abnormality. The (s(mean)) and (e(mean)) for group 1 were lower but (a(mean)) was higher compared with group 2 (all P < .05). The group 1 (e(mean)/a(mean)) was lower (P < .0001) and (E/e(mean)) was higher (P = .003) than in group 2 (both P < .05). (E/e(mean)) and (E/e(lateral wall)) ratios were positively correlated (r = 0.74, P < .05). In patients with early CA due to SA without HF, by DTI, (s(mean)) and (e(mean)) velocities decrease and (a(mean)) velocity increases. These may be markers of subclinical CA of SA when standard echocardiography is not informative. (E/e(mean)) ratio may be an alternative index to (E/e(lateral wall)).

Cardiovascular magnetic resonance in cardiac amyloidosis

BACKGROUND

Cardiac amyloidosis can be diagnostically challenging. Cardiovascular magnetic resonance (CMR) can assess abnormal myocardial interstitium.

METHODS AND RESULTS

Late gadolinium enhancement CMR was performed in 30 patients with cardiac amyloidosis. In 22 of these, myocardial gadolinium kinetics with T1 mapping was compared with that in 16 hypertensive controls. One patient had CMR and autopsy only. Subendocardial T1 in amyloid patients was shorter than in controls (at 4 minutes: 427+/-73 versus 579+/-75 ms; P<0.01), was shorter than subepicardium T1 for the first 8 minutes (P< or =0.01), and was correlated with markers of increased myocardial amyloid load, as follows: left ventricular (LV) mass (r=-0.51, P=0.013); wall thickness (r=-0.54 to -0.63, P<0.04); interatrial septal thickness (r=-0.52, P=0.001); and diastolic function (r=-0.42, P=0.025). Global subendocardial late gadolinium enhancement was found in 20 amyloid patients (69%); these patients had greater LV mass (126+/-30 versus 93+/-25 g/m2; P=0.009) than unenhanced patients. Histological quantification showed substantial interstitial expansion with amyloid (30.5%) but only minor fibrosis (1.3%). Amyloid was dominantly subendocardial (42%) compared with midwall (29%) and subepicardium (18%). There was 97% concordance in diagnosis of cardiac amyloid by combining the presence of late gadolinium enhancement and an optimized T1 threshold (191 ms at 4 minutes) between myocardium and blood.

CONCLUSIONS

In cardiac amyloidosis, CMR shows a characteristic pattern of global subendocardial late enhancement coupled with abnormal myocardial and blood-pool gadolinium kinetics. The findings agree with the transmural histological distribution of amyloid protein and the cardiac amyloid load and may prove to have value in diagnosis and treatment follow-up.

Left atrial systolic function in primary and familial amyloidosis: assessment from left atrial volume change

The severity of left ventricular involvement may differ between primary (PA) and familial amyloidosis (FA). This study examined whether differences in left atrial (LA) systolic function are also present. Twenty-eight patients (18 men, 10 women, aged 59 +/- 12 years) with PA, 17 (11 men, 6 women, aged 40 +/- 11 years) with FA, and 25 normal controls (18 men, 7 women, aged 56 +/- 14 years) underwent transthoracic M-mode, two-dimensional, and Doppler echocardiography. Left atrial volumes were determined at mitral valve (MV) opening (maximal, Vmax), electrocardiographic P wave (onset of atrial systole, Vp), and MV closure (minimal, Vmin) from the apical two-and four-chamber views using the biplane area-length method. Left atrial systolic function was assessed with the LA active emptying volume (ACTEV) = Vp-Vmin and fraction (ACTEF) = ACTEV/Vp. The E/A ratio was increased (1.34 +/- 0.93 vs. 0.89 +/- 0.3), whereas deceleration time was decreased (168.1 +/- 33.7 vs. 196.2 +/- 34.2 ms) in PA compared with FA (p<0.05). Vmax and Vp were similar in PA and FA and greater than in the controls (46.6 +/- 14 vs. 40 +/- 11.4 vs. 27.1 +/- 6.3 cm3/m2, p<0.01, and 33.4 +/- 11.6 vs. 29.7 +/- 10.8 vs. 16.8 +/- 3.8 cm3/m2, p<0.01, respectively). The ACTEV was lower in PA and in the controls than in FA (6.7 +/- 2 vs. 6.2 +/- 2.2 vs. 8.5 +/- 3.3, respectively, p<0.05). The ACTEF was lower in PA than in FA and both were lower than those in the controls (20 +/- 5% vs. 28 +/- 7% vs. 36 +/- 11%, respectively, p<0.01). Despite a similar increase in LA volume, LA systolic dysfunction is more pronounced in PA than in FA. This is most likely due to the restrictive left ventricular physiology possibly associated with depressed LA contractility in the former.

Tissue Doppler imaging in the evaluation of patients with cardiac amyloidosis

PURPOSE OF REVIEW

Although two-dimensional, M-mode, and Doppler echocardiography have played a major role in the assessment of amyloid deposition in the heart, diagnosis of cardiac amyloidosis (CA) based on these conventional techniques is often only possible once the disease is in a relatively advanced stage. To optimize survival, early diagnosis and institution of therapy are essential. Recently, tissue Doppler imaging (TDI) and myocardial strain rate (SR) have emerged as important clinical tools in the assessment of CA.

RECENT FINDINGS

Tissue Doppler imaging-derived modalities including TDI velocities, strain, and SR are currently being used in the early diagnosis and evaluation of patients with CA. Although these new indices have been examined in relatively few patients, findings suggest an important and expanding role of TDI in amyloid infiltration of the heart.

SUMMARY

This review summarizes the recent literature addressing the role of TDI velocities, strain, and SR in the diagnosis and assessment of CA.

Noninvasive diagnosis of biopsy-proven cardiac amyloidosis

OBJECTIVES

This study analyzed the utility of electrocardiographic (ECG) and echocardiographic findings in the diagnosis of amyloidosis proven by endomyocardial biopsy.

BACKGROUND

Cardiac amyloidosis is associated with characteristic ECG and echocardiographic changes, yet each finding alone is relatively nonspecific. A combination of noninvasive prognostic parameters would be desirable for this tissue-based diagnosis.

METHODS

We performed an analysis of 196 consecutive patients referred for endomyocardial biopsy because of clinical suspicion of cardiac amyloidosis. The diagnosis was confirmed in 58 patients (29%). The ECGs, echocardiograms, and right heart hemodynamic data were reviewed to determine which findings strongly correlate with the diagnosis. These findings were then used to build multivariate logistic regression models that predict the log-odds of having cardiac amyloidosis.

RESULTS

The univariate analysis showed that low-voltage and pseudo-infarction patterns on the ECG and increased myocardial thickness and speckled-appearing myocardium on the echocardiogram were associated with biopsy-proven cardiac amyloidosis (each p < 0.01). In multivariate logistic regression models, a combination of a low voltage and measures of myocardial thickness produced the most statistically useful models. For instance, one model showed that if a low voltage was present and interventricular septal thickness is >1.98 cm, the diagnosis of cardiac amyloidosis could be made with a sensitivity of 72% and a specificity of 91%. In this model, the positive predictive and negative predictive values were 79% and 88%, respectively.

CONCLUSIONS

In patients with suspected cardiac amyloidosis, a combination of noninvasive parameters-namely, a low voltage and increased intraventricular septal thickness-is a useful diagnostic tool.

Immunoglobulin light chain amyloidosis and the kidney

Immunoglobulin light chain amyloidosis and the kidney. Amyloidosis (AL) is a common cause of nephrotic syndrome in nondiabetic, nonhypertensive adults. All adult patients with nephrotic syndrome should have immunofixation of serum and urine as a screen. The finding of a monoclonal protein, particularly of lambda type, should lead to a subcutaneous fat aspirate or bone marrow biopsy to search for amyloid deposits. When the result of either test is positive, a kidney biopsy is unnecessary. The prognosis of patients who have renal amyloidosis depends on the concentration of serum creatinine at presentation and whether an echocardiographic evaluation demonstrates infiltrative cardiomyopathy. Most therapies are directed against the plasma cell dyscrasia present in all patients with AL and can include melphalan and prednisone, high-dose dexamethasone, and, most recently, peripheral blood stem cell transplantation.

Polyglandular endocrine failure in a patient with amyloidosis secondary to familial Mediterranean fever

Familial Mediterranean fever (FMF) is 1 of the major causes of secondary amyloidosis. Renal involvement is the main clinical complication and it mostly presents with nephrotic syndrome and chronic renal failure. Although deposition of amyloid has been reported in several endocrine glands such as the adrenal, thyroid, and testes, clinically significant functional impairment is uncommon. Herein, we describe a patient in whom the diagnosis of FMF was based on molecular screening and who presented with recurrent hypoglycemic attacks and extensive amyloid deposition affecting various organ function including adrenal, thyroid, parathyroid, testes, intestinal system, and the heart.

Assessment of the left ventricular diastolic reserve in essential hypertension: the acute saline load test

OBJECTIVE

The aim of this study was to evaluate the significance of the development of a restrictive response to an acute saline load, defined as an increase in the ratio of peak early to peak late diastolic transmitral flow velocity (E/A ratio) associated with a decrease in the deceleration time, in patients with mild to moderate untreated hypertension.

BACKGROUND

Recognised abnormal patterns of transmitral diastolic flow include, from 'best' to 'worst': prolonged relaxation, pseudonormalisation, and restrictive physiology. The common denominator of these transitions is the constellation of an increase in the E/A ratio associated with a decrease in deceleration time.

PATIENTS AND METHODS

Sixteen normal control subjects (6 males, 10 females, age 51.6 +/- 6.9 years) and 24 patients with mild to moderate untreated hypertension (12 males, 12 females, age 46.8 +/- 7.5 years) underwent supine blood pressure measurement with sphygmomanometry, biochemical studies, and transthoracic M-mode, 2D, and Doppler echocardiography before and after an acute saline load (7 mL kg(-1), maximum 500 mL, NaCl 0.9% within 15 min IV).

RESULTS

The baseline E/A ratio was lower (0.90 +/- 0.14 vs. 1.04 +/- 0.18; P < 0.01) and the deceleration time was longer (158.8 +/- 19.4 vs. 135 +/- 8.9 ms; P < 0.01) in patients with hypertension compared with normotensive controls. However, no patient with hypertension exhibited a transmitral flow velocity pattern compatible with typical prolonged relaxation. A restrictive response to the acute saline load was observed in 12 (50%) of the hypertensive and none of the control subjects. Hypertensive patients with a restrictive response to the acute saline load had a lower baseline E velocity (54.8 +/- 8.7 cm s(-1) vs. 66 +/- 6.4 cm s(-1); P = 0.003), a lower baseline E/A ratio (0.83 +/- 0.13 vs. 0.97 +/- 0.12; P = 0.015), and a longer deceleration time (167.5 +/- 15.4 ms vs. 150 +/- 19.5; P = 0.03) than hypertensive patients without such a response.

CONCLUSION

A restrictive response to an acute saline load is indicative of a limited diastolic reserve in patients with mild to moderate untreated hypertension. Further studies are required in order to evaluate the significance of such a response with regards to risk stratification and efficacy of medical treatment in this patient population.