Late enhancement in cardiac amyloidosis: correlation of MRI enhancement pattern with histopathological findings

Dual-Energy Computed Tomography in Cardiac Imaging

Dual-energy computed tomography (DECT) acquires images using two energy spectra and offers a variation of reconstruction techniques for improved cardiac imaging. Virtual monoenergetic images decrease artifacts improving coronary plaque and stent visualization. Further, contrast attenuation is increased allowing significant reduction of contrast dose. Virtual non-contrast reconstructions enable coronary artery calcium scoring from contrast-enhanced scans. DECT provides advanced plaque imaging with detailed analysis of plaque components, indicating plaque stability. Extracellular volume assessment using DECT offers noninvasive detection of myocardial fibrosis. This review aims to outline the current cardiac applications of DECT, summarize recent literature, and discuss their findings.

Prognostic Factors and Survival of Chinese Patients with Cardiac Amyloidosis

Purpose

To identify the survival and prognostic factors for cardiac amyloidosis (CA) in Chinese patients.

Methods

This was a prospective cohort study of 72 patients diagnosed with CA and admitted to the PLA General Hospital between November 2017 and April 2021. Demographic, clinical, laboratory, electrocardiographic, conventional ultrasound, endocardial LS during LV systole (LV ENDO LSsys), and myocardial strain data were recorded. Survival was assessed. All-cause mortality was the endpoint. Follow-up was censored on September 30, 2021.

Results

The mean follow-up was 17.1 ± 12.9 months. Among the 72 patients, 39 died, 23 survived, and 10 were lost to follow-up. Mean survival for all patients was 24.7 ± 2.2 months. Mean survival was 32.7 ± 2.4 months among patients with NYHA class II, 26.6 ± 3.4 months for NYHA class III, and 5.8 ± 1.1 months for NYHA class IV. The multivariate Cox proportional hazard regression model showed that NYHA class (HR = 3.42, 95% CI: 1.36-8.65, P = 0.002), log-proBNP level (HR = 1.40, 95% CI: 1.17-5.83, P = 0.03), and ENDO LSsys of the LV basal level (HR = 1.25, 95% CI: 1.05-1.95, P = 0.004) were independent prognostic factors for CA.

Conclusion

NYHA class, proBNP level, and ENDO LSsys of the LV basal level were independently associated with the survival of patients with CA.

The major factor of left ventricular systolic dysfunction in patients with cardiac amyloidosis: Amyloid overload or microcirculation impairment?

Purpose

Amyloid overload and microcirculation impairment are both detrimental to left ventricular (LV) systolic function, while it is not clear which factor dominates LV functional remodeling in patients with cardiac amyloidosis (CA). The purpose of this study was to investigate the major factor of LV systolic dysfunction using cardiac magnetic resonance imaging.

Materials and methods

Forty CA patients and 20 healthy controls were included in this study. The CA group was divided into two subgroups by the left ventricular ejection fraction (LVEF): patients with reduced LVEF (LVEF < 50%, rLVEF), and patients with preserved LVEF (LVEF ≥ 50%, pLVEF). The scanning sequences included cine, native and post-contrast T1 mapping, rest first-pass perfusion and late gadolinium enhancement. Perfusion and mapping parameters were compared among the three groups. Correlation analysis was performed to evaluate the relationship between LVEF and mapping parameters, as well as the relationship between LVEF and perfusion parameters.

Results

Remarkably higher native T1 value was observed in the rLVEF patients than the pLVEF patients (1442.2 ± 85.8 ms vs. 1407.0 ± 93.9 ms, adjusted p = 0.001). The pLVEF patients showed significantly lower slope dividing baseline signal intensity (slope%BL; rLVEF vs. pLVEF, 55.1 ± 31.0 vs. 46.2 ± 22.3, adjusted p = 0.001) and a lower maximal signal intensity subtracting baseline signal intensity (MaxSI-BL; rLVEF vs. pLVEF, 43.5 ± 23.9 vs. 37.0 ± 18.6, adjusted p = 0.003) compared to the rLVEF patients. CA patients required more time to reach the maximal signal intensity than the controls did (all adjusted p < 0.01). There was no significant correlation between LVEF and first-pass perfusion parameters, while significant negative correlation was observed between LVEF and native T1 (r = -0.434, p = 0.005) in CA patients.

Conclusion

Amyloid overload in the myocardial interstitium may be the major factor of LV systolic dysfunction in CA patients, other than microcirculation impairment.

Multimodality Imaging in the Evaluation and Prognostication of Cardiac Amyloidosis

Cardiac amyloidosis (CA) is an infiltrative cardiomyopathy resulting from deposition of misfolded immunoglobulin light chains (AL-CA) or transthyretin (ATTR-CA) proteins in the myocardium. Survival varies between the different subtypes of amyloidosis and degree of cardiac involvement, but accurate diagnosis is essential to ensure initiation of therapeutic interventions that may slow or potentially prevent morbidity and mortality in these patients. As there are now effective treatment options for CA, identifying underlying disease pathogenesis is crucial and can be guided by multimodality imaging techniques such as echocardiography, magnetic resonance imaging, and nuclear scanning modalities. However, as use of cardiac imaging is becoming more widespread, understanding optimal applications and potential shortcomings is increasingly important. Additionally, certain imaging modalities can provide prognostic information and may affect treatment planning. In patients whom imaging remains non-diagnostic, tissue biopsy, specifically endomyocardial biopsy, continues to play an essential role and can facilitate accurate and timely diagnosis such that appropriate treatment can be started. In this review, we examine the multimodality imaging approach to the diagnosis of CA with particular emphasis on the prognostic utility and limitations of each imaging modality. We also discuss how imaging can guide the decision to pursue tissue biopsy for timely diagnosis of CA.

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 and Results We included all patients diagnosed with amyloid light-chain (AL) or transthyretin cardiac amyloidosis at a tertiary referral center between 2014 to 2020 and undergoing a left ventricular endomyocardial biopsy. Patients (n=37) were more often men (92%), with a median age of 72 years (interquartile range, 68-81). Lambda-positive AL was found in 14 of 19 AL cases (38%) and kappa-positive AL in 5 of 19 (14%), while transthyretin 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 transthyretin amyloidosis. 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 transthyretin amyloidosis and AL subgroups. In 20 patients with myocardial T1 mapping at cardiac magnetic resonance, the combined amyloid and fibrosis extent displayed a modest correlation with extracellular volume (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 cardiac amyloidosis are enlarged to a similar extent by amyloid deposits and fibrotic tissue. Their combination can better explain the increased extracellular volume at cardiac magnetic resonance and circulating biomarkers than amyloid extent alone.

Performance of 99mTc-aprotinin scintigraphy for diagnosing light chain (AL) cardiac amyloidosis confirmed by endomyocardial biopsy

BACKGROUND

Light chain (AL) cardiac amyloidosis is associated with a poor prognosis. Diagnosing at an early stage is critical for treatment and the management of cardiac complication.

PURPOSE

We aimed to evaluate the diagnostic performance of 99mTc-aprotinin images in patients with AL cardiac amyloidosis.

METHODS AND RESULTS

99mTc-aprotinin scintigraphy and endomyocardial biopsy were performed in 10 patients with suspected amyloidosis. Endomyocardial biopsy showed amyloid deposits in 5 of 10 patients. 99mTc-aprotinin (planer image) was positive in 4 of 5 patients who had amyloid deposits in endomyocardial biopsy. On the other hand, all 5 patients without amyloid deposits were negative in planer image. 99mTc-aprotinin (SPECT/CT image) was positive in all 5 patients who had amyloid deposits.

CONCLUSIONS

99mTc-aprotinin scintigraphy is valuable for the non-invasive diagnosis of AL cardiac amyloidosis.

Amyloid cardiomyopathy

Amyloidosis is a heterogeneous group of diseases characterized by the deposition of amyloid. It is caused by extracellular deposition of insoluble fibrils with beta-pleated sheet configuration. The protein misfolding abnormalities result in amyloid fibrils and may manifest as primary, secondary, or familial amyloidosis. Amyloid deposition can occur in multiple organs (eg, heart, liver, kidney, skin, eyes, lungs, nervous system) resulting in a variety of clinical manifestations. Cardiac involvement can occur as part of a systemic disease or as a localized phenomenon. Cardiac involvement in all types of amyloidosis represents a major negative prognostic factor. Early diagnosis, multi-disciplinary cooperation and proper therapy are key aspects of care for patients with amyloid cardiomyopathy. Early diagnosis is crucial, especially in AL amyloidosis, as patients with advanced heart disease are unsuitable candidates for modern, effective hematological treatment including autologous stem cell transplantation. Despite signal development in diagnostics and therapy, the prognosis for patients with advanced cardiac involvement remains poor. This article is an overview of amyloidosis, providing information about the characteristics of cardiac amyloidosis, and present a structured approach to diagnosis, treatment and prognosis of this condition.

Radiologic-Pathologic Correlation of Primary and Secondary Cardiomyopathies: MR Imaging and Histopathologic Findings in Hearts from Autopsy and Transplantation

RSNA, 2017.

Causes and Consequences of Longitudinal LV Dysfunction Assessed by 2D Strain Echocardiography in Cardiac Amyloidosis

OBJECTIVES

The aim of this study was to compare left ventricular longitudinal strain (LS) evaluated by 2-dimensional echocardiography with cardiac magnetic resonance (CMR) in cardiac amyloidosis (CA), establish correlations between histological and imaging findings, and assess the prognostic usefulness of LS measurement and CMR.

BACKGROUND

CA is a condition with a poor prognosis due chiefly to 3 forms of amyloidosis: light-chain amyloidosis (AL), hereditary transthyretin (M-TTR), and wild-type transthyretin (WT-TTR). Two-dimensional echocardiography measurement of LS has been reported to detect early left ventricular systolic dysfunction. The pathophysiological underpinnings, regional distribution, and prognostic significance of LS in CA are unclear.

METHODS

All patients underwent echocardiography, and 53 underwent CMR. The native hearts of the 3 patients who received heart transplants were subjected to histological examination. For each of the 17 left ventricular segments in the American Heart Association model, we evaluated LS, late gadolinium enhancement (LGE) by CMR, and cardiac amyloid deposition. Univariate and multivariate analyses were performed at 6 months to identify variables associated with major adverse cardiac events (MACE).

RESULTS

We studied 79 patients with CA; 26 had AL, 36 M-TTR, and 17 WT-TTR. Mean LS was -10 ± 4%. Both LS and amyloid deposits showed a basal-to-apical gradient. The mean LS and number of segments with LGE were similar across the 3 CA types. LS correlated with LGE and amyloid burden (r = 0.72). LGE was seen in the 6 basal segments in all WT-TTR patients. During the median follow-up of 11 months (range 4 to 17 months), 36 (46%) patients experienced MACE. Independent predictors of MACE were apical LS (cutoff, -14.5%), N-terminal pro-B-type natriuretic peptide (cutoff, 4,000 ng/l), and New York Heart Association functional class III to IV heart failure.

CONCLUSIONS

Basal-to-apical LS abnormalities are similar across CA types and reflect the amyloid burden. Apical LS independently predicts MACE.

Late gadolinium enhancement in cardiac amyloidosis: attributable both to interstitial amyloid deposition and subendocardial fibrosis caused by ischemia

Gadolinium contrast agents used for late gadolinium enhancement (LGE) distribute in the extracellular space. Global diffuse myocardial LGE pronounced in the subendocardial layers is common in cardiac amyloidosis. However, the pathophysiological basis of these findings has not been sufficiently explained. A 64-year-old man was admitted to our hospital with leg edema and nocturnal dyspnea. Bence Jones protein was positive in the urine, and an endomyocardial and skin biopsy showed light-chain (AL) amyloidosis. He died of ventricular fibrillation 3 months later. 9 days before death, the patient was examined by cardiac magnetic resonance (CMR) imaging on a 3-T system. We acquired LGE data at 2, 5, 10, and 20 min after the injection of gadolinium contrast agents, with a fixed inversion time of 350 ms. Myocardial LGE developed sequentially. The myocardium was diffusely enhanced at 2 min, except for the subendocardium, but LGE had extended to almost the entire left ventricle at 5 min and predominantly localized to the subendocardial region at 10 and 20 min. An autopsy revealed massive and diffused amyloid deposits in perimyocytes throughout the myocardium. Old and recent ischemic findings, such as replacement fibrosis and coagulative myocyte necrosis, were evident in the subendocardium. In the intramural coronary arteries, mild amyloid deposits were present within the subepicardial to the mid layer of the left ventricle, but no stenotic lesions were evident. However, capillaries were obstructed by amyloid deposits in the subendocardium. In conclusion, the late phase of dynamic LGE (at 10 and 20 min) visualized in the subendocardium corresponded to the interstitial amyloid deposition and subendocardial fibrosis caused by ischemia in our patient.

Myocardial T1 mapping: techniques and potential applications

Myocardial fibrosis is a common endpoint in a variety of cardiac diseases and a major independent predictor of adverse cardiac outcomes. Short of histopathologic analysis, which is limited by sampling bias, most diagnostic modalities are limited in their depiction of myocardial fibrosis. Cardiac magnetic resonance (MR) imaging has the advantage of providing detailed soft-tissue characterization, and a variety of novel quantification methods have further improved its usefulness. Contrast material-enhanced cardiac MR imaging depends on differences in signal intensity between regions of scarring and adjacent normal myocardium. Diffuse myocardial fibrosis lacks these differences in signal intensity. Measurement of myocardial T1 times (T1 mapping) with gadolinium-enhanced inversion recovery-prepared sequences may depict diffuse myocardial fibrosis and has good correlation with ex vivo fibrosis content. T1 mapping calculates myocardial T1 relaxation times with image-based signal intensities and may be performed with standard cardiac MR imagers and radiologic workstations. Myocardium with diffuse fibrosis has greater retention of contrast material, resulting in T1 times that are shorter than those in normal myocardium. Early studies have suggested that diffuse myocardial fibrosis may be distinguished from normal myocardium with T1 mapping. Large multicenter studies are needed to define the role of T1 mapping in developing prognoses and therapeutic assessments. However, given its strengths as a noninvasive method for direct quantification of myocardial fibrosis, T1 mapping may eventually play an important role in the management of cardiac disease.

Tissue characterization of the myocardium: state of the art characterization by magnetic resonance and computed tomography imaging

Late gadolinium enhancement (LGE) is a simple, robust, well-validated method for assessing scar in acute and chronic myocardial infarction. LGE is useful for distinguishing between ischemic and nonischemic cardiomyopathy. Specific LGE patterns are seen in nonischemic cardiomyopathy. Patient studies using T1 mapping have varied in study, design, and acquisition sequences. Despite the differences in technique, a clear pattern that has been seen is that in cardiac disease postcontrast T1 times are shorter. Extracellular volume fraction measured with cardiac computed tomography represents a new approach to the clinical assessment of diffuse myocardial fibrosis by evaluating the distribution of iodinated contrast.

2014 korean guidelines for appropriate utilization of cardiovascular magnetic resonance imaging: a joint report of the korean society of cardiology and the korean society of radiology

Cardiac magnetic resonance (CMR) imaging is now widely used in several fields of cardiovascular disease assessment due to recent technical developments. CMR can give physicians information that cannot be found with other imaging modalities. However, there is no guideline which is suitable for Korean people for the use of CMR. Therefore, we have prepared a Korean guideline for the appropriate utilization of CMR to guide Korean physicians, imaging specialists, medical associates and patients to improve the overall medical system performances. By addressing CMR usage and creating these guidelines we hope to contribute towards the promotion of public health. This guideline is a joint report of the Korean Society of Cardiology and the Korean Society of Radiology.

The diagnostic performance of cardiac magnetic resonance in detection of myocardial involvement in AL amyloidosis

BACKGROUND

The non-invasive assessment of amyloid heart disease may be challenging. Cardiac magnetic resonance (CMR) represents a method of choice for assessment of left ventricular (LV) morphology and function, and it also provides a unique possibility to evaluate the presence of amyloid deposition by the late gadolinium enhancement (LGE) technique. However, so far, published studies have not been consistent in terms of described LGE patterns associated with amyloid cardiomyopathy.

AIMS

To compare echocardiographic and CMR assessment of LV morphology and function and to evaluate the presence and pattern of LGE in a population of patients with AL amyloid cardiomyopathy.

METHODS

Twenty-two consecutive patients with newly diagnosed AL amyloid cardiomyopathy and without contraindications to CMR were comprehensively examined by echocardiography and CMR.

RESULTS

Echocardiography and CMR did not differ in the evaluation of interventricular septal thickness, LV end-diastolic diameter and ejection fraction. Significant differences were found between echocardiographic and CMR estimates of LV end-diastolic volume (P<0·01) and LV mass (P<0·001). Various global LGE patterns (transmural homogenous or heterogeneous, subendocardial) were present in 17 patients (77%), patchy LGE was observed in one case (4·5%) and suboptimal nulling of the myocardium was reported in two subjects (9%).

CONCLUSIONS

Echocardiography significantly overestimates LV mass and underestimates LV volumes in patients with AL amyloid cardiomyopathy as compared to CMR. As it is present in more than three quarters of individuals with AL amyloid cardiomyopathy, any type of global LGE pattern may be considered as pathogenomic for amyloid heart disease.

2014 Korean guidelines for appropriate utilization of cardiovascular magnetic resonance imaging: a joint report of the Korean Society of Cardiology and the Korean Society of Radiology

Cardiac magnetic resonance (CMR) imaging is now widely used in several fields of cardiovascular disease assessment due to recent technical developments. CMR can give physicians information that cannot be found with other imaging modalities. However, there is no guideline which is suitable for Korean people for the use of CMR. Therefore, we have prepared a Korean guideline for the appropriate utilization of CMR to guide Korean physicians, imaging specialists, medical associates and patients to improve the overall medical system performances. By addressing CMR usage and creating these guidelines we hope to contribute towards the promotion of public health. This guideline is a joint report of the Korean Society of Cardiology and the Korean Society of Radiology.

Determining the role of fibrosis in hypertrophic cardiomyopathy

Fibroblast activity within the heart may be considered a basically constructive process. Hyperactivity of fibroblasts, however, may result in the accumulation of extracellular matrix proteins with adverse effects on cardiac structure and function including electrical instability and increased risk of arrhythmogenic cardiac death. The detection of cardiac fibrosis by dedicated imaging techniques, mainly gadolinium-enhanced MRI, holds promise to refine patient management in a variety of cardiac conditions. This review aims to summarize the current knowledge regarding fibrosis in hypertrophic cardiomyopathy.

MRI differentiation of cardiomyopathy showing left ventricular hypertrophy and heart failure: differentiation between cardiac amyloidosis, hypertrophic cardiomyopathy, and hypertensive heart disease

PURPOSE

To evaluate the capability of MRI to differentiate cardiac amyloidosis (CA), end-stage hypertrophic cardiomyopathy (HCM), and hypertensive heart disease (HHD), which are important etiologies of left ventricular hypertrophy (LVH) and heart failure.

MATERIALS AND METHODS

We enrolled 26 patients presenting with both LVH and heart failure: six with CA, nine with end-stage HCM, and 11 with HHD. Cardiac function, presence of pericardial or pleural effusion, and the extent and patterns of late gadolinium enhancement (LGE) were compared among the three diseases.

RESULTS

Myocardial LGE was observed in all six CA patients, eight end-stage HCM patients, and six HHD patients. The number of LGE segments was significantly greater in CA than in HCM or HHD (p = 0.02 for both), and all patients with CA showed a global endocardial pattern of LGE. There were significant differences among CA, HCM, and HHD in ejection fraction and end-diastolic and end-systolic volume indices (p < 0.05 for all). Pericardial effusion was observed more frequently in CA than in HCM or HHD (p = 0.04 or 0.01, respectively).

CONCLUSION

MRI is valuable for distinguishing among CA, end-stage HCM, and HHD, all of which present with LVH and heart failure.

Monitoring systemic amyloidosis using MRI measurements of the extracellular volume fraction

We report the in vivo evaluation, in a murine model, of MRI measurements of the extracellular volume fraction (ECV) for the detection and monitoring of systemic amyloidosis. A new inducible transgenic model was used, with increased production of mouse serum amyloid A protein controlled by oral administration of doxycycline, that causes both the usual hepatic and splenic amyloidosis and also cardiac deposits. ECV was measured in vivo by equilibrium contrast MRI in the heart and liver of 11 amyloidotic and 10 control mice. There was no difference in the cardiac function between groups, but ECV was significantly increased in the heart, mean (standard deviation) 0.20 (0.05) versus 0.14 (0.04), p < 0.005, and liver, 0.27 (0.04) versus 0.15 (0.04), p < 0.0005, of amyloidotic animals and was strongly correlated with the histological amyloid score, myocardium, ρ = 0.67, p < 0.01; liver, ρ = 0.87, p < 0.01. In a further four mice that received human serum amyloid P component (SAP) followed by anti-human SAP antibody, a treatment to eliminate visceral amyloid deposits, ECV in the liver and spleen returned to baseline after therapy (p < 0.01). MRI measurement of ECV is a sensitive marker of amyloid deposits with potential application for early detection and monitoring therapies promoting their clearance.

Comparison between (99m)Tc-diphosphonate imaging and MRI with late gadolinium enhancement in evaluating cardiac involvement in patients with transthyretin familial amyloid polyneuropathy

OBJECTIVE

Cardiac involvement is not rare in systemic amyloidosis and is associated with poor prognosis. Both (99m)Tc-diphosphonate imaging and cardiac MRI with late gadolinium enhancement are considered valuable tools in revealing amyloid deposition in the myocardium; however, to our knowledge, no comparative study between the two techniques exists. We compared findings of these two techniques in patients with transthyretin-familial amyloid polyneuropathy (FAP).

SUBJECTS AND METHODS

Eighteen patients with transthyretin-FAP underwent (99m)Tc-diphosphonate imaging and MRI with late gadolinium enhancement. Images were visually evaluated by independent readers to determine the presence of radiotracer accumulation or late gadolinium enhancement-positive areas at the level of cardiac chambers.

RESULTS

Interobserver agreement ranged from moderate to very good for (99m)Tc-diphosphonate imaging findings and was very good for findings of MRI with late gadolinium enhancement. Left ventricle (LV) radiotracer uptake was found in 10 of 18 patients, whereas LV late gadolinium enhancement-positive areas were found in eight of 18 patients (χ(2) = 0.9; p = 0.343). One hundred fifty-nine LV segments showed (99m)Tc-diphosphonate accumulation, and 57 LV segments were late gadolinium enhancement positive (p < 0.0001). Radiotracer uptake was found in the right ventricle (RV) in eight patients and in both atria in five patients, whereas MRI showed that RV was involved in three patients and both atria in six patients; the differences were not statistically significant (RV, p = 0.07; atria, p = 1). Intermodality agreement between (99m)Tc-diphosphonate imaging and MRI ranged from fair to good.

CONCLUSION

Our study shows that, although (99m)Tc-diphosphonate imaging and MRI with late gadolinium enhancement have similar capabilities to identify patients with myocardial amyloid deposition, cardiac amyloid infiltration burden can be significantly underestimated by visual analysis of MRI with late gadolinium enhancement compared with (99m)Tc-diphosphonate imaging.

Value of cardiovascular magnetic resonance in suspected cardiac amyloidosis

The diagnosis of cardiac amyloid can be challenging; requiring a high clinical index of suspicion and often many diagnostic tests to confirm. We describe a case demonstrating the characteristic pattern of amyloid by cardiovascular magnetic resonance and how this imaging modality can aid in the diagnosis.

Quantification of extracellular matrix expansion by CMR in infiltrative heart disease

OBJECTIVES

The aim of this study was to perform direct quantification of myocardial extracellular volume fraction (ECF) with T1-weighted cardiac magnetic resonance (CMR) imaging in patients suspected to have infiltrative heart disease.

BACKGROUND

Infiltrative heart disease refers to accumulation of abnormal substances within the myocardium. Qualitative assessment of late gadolinium enhancement (LGE) remains the most commonly used method for CMR evaluation of patients suspected with myocardial infiltration. This technique is widely available and can be performed in a reproducible and standardized manner. However, the degree of extracellular matrix expansion due to myocardial infiltration in the intercellular space has, to date, not been amenable to noninvasive quantification with LGE.

METHODS

We performed 3-T CMR in 38 patients (mean age 68 ± 15 years) who were referred for assessment of infiltrative heart disease and also in 9 healthy volunteers as control subjects. The T1 quantification by Look-Locker gradient-echo before and after contrast determined segmental myocardial partition coefficients. The ECF was obtained by referencing the tissue partition coefficient for gadolinium to the plasma volume fraction in blood, derived from serum hematocrit. Cine CMR and LGE imaging in matching locations were also performed.

RESULTS

Seventeen patients (45%) had cardiac amyloidosis (CA) (biopsy-confirmed or clinically highly probable), 20 (53%) had a non-amyloid cardiomyopathy, and 1 had lysosomal storage disease. Median global ECF was substantially higher in CA patients (0.49) compared with non-amyloid cardiomyopathy patients (0.33, p < 0.0001) and volunteers (0.24, p = 0.0001). The ECF strongly correlated with visually assessed segmental LGE (r = 0.80, p < 0.0001) and LV mass index (r = 0.69, p < 0.0001), reflecting severity of myocardial infiltration. In patients with CA, ECF was highest in segments with LGE, although it remained elevated in segments without qualitative LGE.

CONCLUSIONS

The CMR ECF quantification identified substantial expansion of the interstitial space in patients with CA compared with volunteers. Further studies using this technique for diagnosis and assessment of the severity of myocardial infiltration are warranted.

Longitudinal left ventricular function for prediction of survival in systemic light-chain amyloidosis: incremental value compared with clinical and biochemical markers

OBJECTIVES

The aim of the study was to determine whether longitudinal left ventricular (LV) function provides prognostic information in a large cohort of patients with systemic light-chain (AL) amyloidosis.

BACKGROUND

AL amyloidosis is associated with a high incidence of cardiovascular events. Reduced myocardial longitudinal function is one of the hallmarks of myocardial involvement in this rare disease.

METHODS

Two hundred six consecutive patients with biopsy-proven AL amyloidosis were investigated in this prospective observational study. Echocardiographic imaging parameters, mean tissue Doppler-derived longitudinal strain (LS), and two-dimensional global longitudinal strain (2D-GLS) of the LV, cardiac serological biomarkers, and comprehensive clinical disease characteristics were assessed. The primary endpoint was all-cause mortality or heart transplantation.

RESULTS

After a median follow-up of 1207 days, LS and 2D-GLS were significant predictors of survival in AL amyloidosis. The cutoff values discriminating survivors from nonsurvivors were -10.65% for LS and -11.78% for 2D-GLS. In a multivariable echocardiographic Cox model, only diastolic dysfunction and 2D-GLS remained as independent predictors of survival. In comprehensive clinical models, 2D-GLS (p < 0.0001), diastolic dysfunction (p < 0.01), the pathologic free light chains (p < 0.05), cardiac troponin-T (cTnT) (p < 0.01), and the Karnofsky index (p < 0.001) remained as independent predictors. 2D-GLS delineated a superior prognostic value compared with that derived from pathologic free light chains or cTnT in patients evaluated before firstline chemotherapy (n = 113; p < 0.0001), and remained the only independent predictor besides the Karnofsky index in subjects with preserved LV ejection fraction (≥50%; n = 127; p < 0.01). LS and 2D-GLS both offered significant incremental information (p < 0.001) for the assessment of outcome compared with clinical variables (age, Karnofsky index, and New York Heart Association functional class) and serological biomarkers.

CONCLUSIONS

In the largest serial investigation reported so far, reduced LV longitudinal function served as an independent predictor of survival in AL amyloidosis and offered incremental information beyond standard clinical and serological parameters.

Amyloid diseases of the heart: current and future therapies

Amyloid diseases in man are caused by as many as 23 different pre-cursor proteins already described. Cardiologists predominantly encounter three main types of amyloidosis that affect the heart: light chain (AL) amyloidosis, senile systemic amyloidosis (SSA) and hereditary amyloidosis, most commonly caused by a mutant form of transthyretin. In the third world, secondary amyloid (AA) is more prevalent, due to chronic infections and inadequately treated inflammatory conditions. Much less common, are the non-transthyretin variants, including mutations of fibrinogen, the apolipoproteins apoA1 and apoA2 and gelsolin. These rarer types do not usually cause significant cardiac compromise. Occurring worldwide, later in life and of less clinical significance, isolated atrial amyloid (IAA) also involves the heart. Heart involvement by amyloid often has devastating consequences. Clinical outcome depends on amyloid type, the extent of systemic involvement and the treatment options available. An exact determination of amyloid type is critical to appropriate therapy. In this review we describe the different approaches required to treat this spectrum of amyloid cardiomyopathies.

New pathological insights into cardiac amyloidosis: implications for non-invasive diagnosis

BACKGROUND

Knowledge of the patterns of myocardial amyloid accumulation could improve the interpretation of electrocardiographic, echocardiographic and magnetic resonance imaging findings of amyloidosis. We assessed the extent and pattern of myocardial amyloid infiltration in explanted or autopsied hearts of patients with cardiomyopathy related to acquired monoclonal immunoglobulin light-chain (AL) or hereditary transthyretin (TTR) related amyloidosis (ATTR).

METHODS

We analyzed nine explanted/autopsied hearts from patients with AL (n = 4) and ATTR (n = 5) cardiac amyloidosis. For each heart, a biventricular histological macrosection was obtained at mid-ventricular level and analyzed with both inspective and computer-assisted histologic and histomorphometric analysis aimed in particular at quantifying muscle cells, fibrosis and amyloid infiltration.

RESULTS

The extent of amyloid infiltration of the left ventricle (LV) ranged from 45 to 76% (median [interquartile range (IQR)] = 57% [51-64]) of the overall surface. Although LV trabecular and subendocardial were the most infiltrated layers (45-94%, median [IQR] = 73% [67-84] and from 44 to 71%, median [IQR] = 57% [49-59], respectively), intra- and inter-patient heterogeneity was high. Three main patterns of amyloid infiltration of the LV were identified: diffuse (five cases), mainly subendocardial (two cases), and mainly segmental (two cases). The extent of amyloid infiltration of the right ventricle ranged from 48 to 93% (median [IQR] = 61% [59-83]); contributions of parietal and trabecular layers ranged from 32 to 99% (median [IQR] = 63% [47-88]) and from 49 to 93% (median [IQR] = 74% [64-79]), respectively.

CONCLUSIONS

In amyloidotic cardiomyopathy, amyloid deposition is highly heterogeneous. Different patterns of infiltration are identifiable, including diffuse, mainly segmental and mainly subendocardial. Awareness of this variability can help the interpretation of ECGs, echocardiograms and magnetic resonance imaging.

Transthyretin cardiac amyloidoses in older North Americans

The amyloidoses are a group of hereditary or acquired disorders caused by the extracellular deposition of insoluble protein fibrils that impair tissue structure and function. All amyloidoses result from protein misfolding, a common mechanism for disorders in older persons, including Alzheimer's disease and Parkinson's disease. Abnormalities in the protein transthyretin (TTR), a serum transporter of thyroxine and retinol, is the most common cause of cardiac amyloidoses in elderly adults. Mutations in TTR can result in familial amyloidotic cardiomyopathy, and wild-type TTR can result in senile cardiac amyloidosis. These underdiagnosed disorders are much more common than previously thought. The resulting restrictive cardiomyopathy can cause congestive heart failure, arrhythmias, and advanced conduction system disease. Although historically difficult to make, the diagnosis of TTR cardiac amyloidosis has become easier in recent years with advances in cardiac imaging and more widespread use of genetic analysis. Although therapy has largely involved supportive medical care, avoidance of potentially toxic agents, and rarely organ transplantation, the near future brings the possibility of targeted pharmacotherapies designed to prevent TTR misfolding and amyloid deposition. Because these disease-modifying agents are designed to prevent disease progression, it has become increasingly important that older persons with TTR amyloidosis be expeditiously identified and considered for enrollment in clinical registries and trials.

[Amyloidosis of the heart]

Amyloidosis is a heterogeneous group of diseases characterized by the pathological deposition of autologous proteins in an antiparallel β-sheet confirmation forming non-branching linear fibrils of indefinite length and an approximate diameter of 10-12 nm. Cardiac amyloidosis is caused by deposits in the heart and may lead to cardiac arrhythmia and low output failure. Following the diagnosis, classification of the amyloid protein and evaluation of further organ involvement is mandatory. Treatment approaches are based on reduction of the production of amyloid precursor proteins. Standard heart failure treatment is usually not well tolerated and the underlying disease remains unaffected. Cardiac amyloidosis, especially of the light chain type, is associated with a poor outcome. The clinical picture is uncharacteristic, therefore correct diagnosis of cardiac amyloidosis is often delayed in many patients. Combination of clinical symptoms of different organ systems should alert the physician to the diagnosis of amyloidosis.

Delayed contrast enhancement on MR images of myocardium: past, present, future

Differential enhancement of myocardial infarction was first recognized on computed tomographic (CT) images obtained with iodinated contrast material in the late 1970s. Gadolinium enhancement of myocardial infarction was initially reported for T1-weighted magnetic resonance (MR) imaging in 1984. The introduction of an inversion-recovery gradient-echo MR sequence for accentuation of the contrast between normal and necrotic myocardium was the impetus for widespread clinical use for demonstrating the extent of myocardial infarction. This sequence has been called delayed-enhancement MR and MR viability imaging. The physiologic basis for differential enhancement of myocardial necrosis is the greater distribution volume of injured myocardium compared with that of normal myocardium. It is now recognized that delayed enhancement occurs in both acute and chronic (scar) infarctions and in an array of other myocardial processes that cause myocardial necrosis, infiltration, or fibrosis. These include myocarditis, hypertrophic cardiomyopathy, amyloidosis, sarcoidosis, and other myocardial conditions. In several of these diseases, the presence and extent of delayed enhancement has prognostic implications. Future applications of delayed enhancement with development of MR imaging and CT techniques will be discussed.

Amyloid in endomyocardial biopsies

The prognosis of cardiac amyloidosis depends on the nature and origin of the amyloid protein deposited. However, little is known about the prevalence and origin of amyloid in heart muscle biopsies. We therefore examined retrospectively the distribution and origin of amyloid in a consecutive series of endomyocardial biopsies. Endomyocardial biopsies with verified presence of amyloid from 101 patients were included. Amyloid was classified immunohistochemically in each of them. Our collective comprised 63 men and 38 women, with a mean age of 66 years (range 37-85 years). Cardiac amyloidosis was the most common of the AL (54 patients) or ATTR type (42 patients). In five individuals, amyloid remained unclassified. AL amyloidosis was subdivided into ALlambda (45 patients) and ALkappa amyloid (nine patients). AA amyloid was not found in any individual. The amount of amyloid was higher in AL than in ATTR amyloidosis. Genomic DNA was extracted and examined by DNA sequencing in 19 patients with ATTR amyloidosis. Five (26%) individuals carried TTR mutations (p.Val20Ile, p.Val30Met (twice), p.Asp39Val and p.Glu54Asp) and were classified as suffering from hereditary ATTR amyloidosis. Amyloid in endomyocardial biopsies is most commonly of immunoglobulin light chain origin, followed by non-hereditary and hereditary-type ATTR amyloid.

Serum levels of NT-proBNP as surrogate for cardiac amyloid burden: new evidence from gadolinium-enhanced cardiac magnetic resonance imaging in patients with amyloidosis

BACKGROUND

The prognostic value of NT-proBNP has been recognized in patients with amyloidosis complicated by cardiac involvement. We aimed to use contrast enhanced cardiac magnetic resonance imaging (CMR) to identify functional and structural alterations related to levels of NT-proBNP better to understand the mechanisms of its release in cardiac amyloidosis.

METHODS AND RESULTS

CMR was performed on a 1.5-T scanner in 34 patients with biopsy proven amyloid light chain (AL; n = 27) or hereditary transthyretin related (TTR; n = 7) amyloidosis. NT-proBNP was higher in patients with (n = 25) compared to patients without cardiac involvement (n = 9) (2931 (IQR: 972-8629; min-max: 25-27,277) pg/ml vs. 177 (IQR: 71-1431; min-max: 22-7935) pg/ml, p = 0.008). ROC analysis identified a NT-proBNP of <2426.5 pg/ml as optimal discriminator for event free survival (682 +/- 65 days). NT-proBNP did not correlate with LV- ejection fraction, end-diastolic and end-systolic volumes or stroke volume. There was a moderate correlation between NT-proBNP and LV-mass (R = 0.52, p = 0.003) and extent of late gadolinium enhancement (LGE; R = 0.41, p = 0.04).

CONCLUSIONS

This study confirms the prognostic value of NT-proBNP in patients with AL and TTR amyloidosis and provides the novel finding that NT-proBNP correlates with surrogates of myocardial amyloid burden such as LV-mass and LGE, supporting the concept of NT-proBNP as a biomarker reflecting the severity of cardiac amyloid infiltration.

[Risk stratification and treatment of cardiac amyloidoses]

Cardiac amyloidoses are a heterogeneous group of cardiomyopathies that are resistant to treatment and are associated with a poor outcome. Standard heart failure treatment is usually not well tolerated and the underlying disease remains unaffected. The clinical picture is uncharacteristic. Cardiac amyloidosis is often associated with dysfunction of additional organs. Early cardiac amyloid involvement usually reveals left ventricular hypertrophy, impairment of longitudinal shortening and diastolic ventricular function. Without adequate therapy (bi-)ventricular hypertrophy will progress to severe systolic ventricular function decrease. The combination of low voltage pattern, left ventricular hypertrophy and granular sparkling is characteristic for advanced cardiac amyloid involvement. Cardiac magnetic resonance imaging and scintigraphy yield further information on the pattern and severity of cardiac involvement. In unclear cases (left ventricular) endomyocardial biopsy is necessary. Detection of early cardiac involvement and proper identification of patients at high risk for sudden cardiac death due to rapid progressive amyloidosis is still incompletely defined. Referral to specialized centers is strongly recommended.