|
|
||||||||||
|
J Am Coll Cardiol, 2004; 43:410-415, doi:10.1016/j.jacc.2003.08.043 © 2004 by the American College of Cardiology Foundation |



* Division of Cardiology, Department of Medicine, Baltimore, Maryland, USA
Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
Department of Biostatistics, Johns Hopkins School of Public Health and Hygiene, Baltimore, Maryland, USA
Manuscript received April 30, 2003; revised manuscript received August 21, 2003, accepted August 25, 2003.
* Reprint requests and correspondence: Dr. Edward K. Kasper, Chief of Cardiology, Johns Hopkins Bayview Medical Center, 4940 Eastern Avenue, Baltimore, Maryland 212242780., USA
ekasper{at}jhmi.edu
| Abstract |
|---|
|
|
|---|
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 parametersnamely, a low voltage and increased intraventricular septal thicknessis a useful diagnostic tool.
| ||||||||||||||
The diagnosis of cardiac amyloidosis can be difficult because the clinical presentation is similar to that of other cardiomyopathies. Cardiac amyloidosis is suggested by characteristic echocardiographic findingsnamely, a granular myocardial appearance, thickened ventricular walls, atrial dilation, and diastolic dysfunction progressing to systolic dysfunction (2). The ECG frequently demonstrates low-voltage and pseudo-infarct patterns, conduction abnormalities, and arrhythmias. However, each finding alone is nonspecific. In this study, we aimed to determine which parameters or combination of parameters correlate with endomyocardial biopsy-proven cardiac amyloidosis and thus can be used to predict disease status.
| Methods |
|---|
|
|
|---|
A review of the medical records was performed by a team of physicians blinded to the endomyocardial biopsy results. Biopsy results were separated from other patient information and introduced into the data base after collection of clinical data was completed. The following information was reviewed and recorded: demographic data, New York Heart Association (NYHA) heart failure class at the time of biopsy, ECG findings, echocardiographic results, and hemodynamic parameters derived from right heart catheterization performed at the time of biopsy.
The ECGs were analyzed for the following characteristics: rhythm, conduction abnormalities (i.e., right or left bundle branch block), a low-voltage pattern (defined by total height of the QRS complex in the limb leads <5 mm and <10 mm in the precordial leads), a pseudo-infarction pattern (pathologic Q waves on the ECG, but no coronary artery disease by angiography), and a left or right atrial abnormality. The echocardiograms were analyzed for the following characteristics: interventricular septal (IVS) thickness, posterior wall thickness, left ventricular (LV) diastolic diameter, LV systolic diameter, atrial size, pericardial effusion size (if present), overall ejection fraction, and granular/sparking appearance of the myocardium by visual inspection. Standard hemodynamic data obtained from right heart catheterizations were reviewed.
Endomyocardial biopsy. The endomyocardial biopsies were obtained in the standard fashion. A minimum of four biopsies were taken from each patient. All biopsies were examined by a single, experienced pathologist who was blinded to all other study data. The biopsies were analyzed with a standard hematoxylin-eosin preparation. All biopsies were also stained with congo red to identify the presence of amyloidosis. If the congo red staining was equivocal, the biopsy was reviewed under electron microscopy to confirm the diagnosis. Finally, all biopsies with amyloidosis underwent immunohistochemical staining to help ascertain the exact etiology of the amyloid. Staining was performed for amyloid AL and transthyretin. They were also stained for thioflavin T, a more sensitive stain for amyloidosis (compared with congo red staining), but not specific for the source of the amyloid. Stains for lambda and kappa light chains were available in a limited number of the patients.
Statistical analysis. All statistical analyses were performed using the statistical software package STATA version 7.0. As an initial step, univariate analyses were performed on all demographic and cardiac variables of interest to determine which set of variables was statistically associated with cardiac amyloidosis. Continuous variables were assessed using the parametric t test for independent samples (e.g., mean arterial pressure, right ventricular systolic pressure), and all categorical variables were assessed using the chi-square goodness-of-fit test (e.g., square root sign). Those variables that were found to be associated with disease status were then used to build multivariate logistic regression models that predict the log-odds of being positive for amyloidosis on endomyocardial biopsy. We first considered models with only noninvasive cardiac variables and then added invasive measures to see whether these variables would increase our ability to predict disease status.
| Results |
|---|
|
|
|---|
|
Patient characteristics. The demographic, clinical, and hemodynamic characteristics of the patients, according to their biopsy results, are shown in Tables 2 and 3. Patients in the amyloidosis group were slightly older and more often male. The duration of symptoms before obtaining the biopsy was no different between the groups. However, the amyloidosis group had a larger percentage of patients with more advanced heart failure (i.e., NYHA class III/IV). The hemodynamic data are also consistent with a greater degree of hemodynamic compromise in the amyloidosis group.
|
|
|
|
|
|
This model can also be used to formulate a simple yet powerful test for the likelihood of amyloidosis. By utilizing the mathematic equations that define this model, one is able to define a cut-off point for IVS thickness, which can serve as a testing parameter (Appendix). We have demonstrated that for patients with a low voltage, a cut-off point of 1.98 cm for IVS thickness optimizes both the sensitivity and specificity of our model to predict the presence of amyloidosis. Similarly, a cut-off point of 1.13 cm for IVS thickness can be defined as the testing point that maximizes the sensitivity and specificity of the test for patients without a low voltage. Thus, in our test, a patient with an ECG that shows a low voltage and an echocardiogram with an IVS thickness of
1.98 cm will be classified as having amyloidosis. Likewise, a patient with a low voltage but IVS thickness <1.98 cm would be classified as not having amyloidosis. Our test yields a positive predictive value of 79% and a negative predictive value of 88%. Table 8 shows the sensitivity, specificity, and positive and negative predictive values of our test.
|
| Discussion |
|---|
|
|
|---|
Logistic regression models that predict the log-odds of cardiac amyloidosis were developed, based on noninvasive parameters. Multiple models were used to determine the diagnostic parameters of sensitivity, specificity, and predictive value. Models using myocardial echogenicity paired with wall thickness or low voltage were highly predictive of cardiac amyloidosis, but not more so than the selected model utilizing septal thickness and low voltage. Use of these variables is simpler and lessens the variability associated with identifying granular myocardium. We propose that in patients with clinical suspicion of cardiac amyloid, the combination of septal thickness and low voltage can be used for diagnosis. Additionally, serial echocardiography can be used to follow the patient's clinical status and response to treatment. Others have demonstrated that increasing LV wall thickness and mass/voltage ratio are associated with shorter survival (7).
Study limitations. This study has several limitations. Patients were referred for suspicion of cardiac amyloidosis and therefore likely had an increased incidence of ECG and echocardiographic evidence of myocardial involvement. However, this would lessen any observed difference between the groups. A chart review did not provide sufficient information to determine the NYHA heart failure class at the time of echocardiography and endomyocardial biopsy. It has been demonstrated that clinical CHF strongly correlates with the degree of echocardiographic abnormalities, in particular, increased wall thickness (7). In this study, a higher incidence of clinical CHF in those with histologic evidence of cardiac amyloid would falsely create or amplify a difference in echocardiographic abnormalities between groups. However, it has been demonstrated that ECG and echocardiographic changes consistent with amyloid are detectable before the development of CHF (8).
Another confounding factor may be the combined analysis using primary and secondary amyloidosis. It is known that the type and amount of cardiac dysfunction is related to the type and extent of amyloid infiltration. At autopsy, it has been demonstrated that septal thickness is higher in primary and familial amyloidosis than in secondary amyloidosis (9). Studies comparing echocardiographic findings between types of amyloidosis have yielded conflicting results. One study demonstrated an increased IVS thickness in primary amyloidosis compared with familial and secondary amyloidosis (10), but another study did not show any significant difference in septal thickness between primary and familial amyloidosis (11). It is also known that amyloid AA rarely involves the heart (12), so the potential effect on interpretation of this data is unclear.
Cardiac amyloidosis is associated with a variable prognosis. In primary amyloidosis, the median survival is six months once heart failure develops. For senile amyloidosis, the median survival is five years once heart failure develops (13). Because of therapeutic and prognostic implications, it is important that a tissue diagnosis is made. We propose that if a histopathologic diagnosis is available from other tissue, that the findings of increased septal thickness and low voltage are sufficient for the diagnosis of cardiac amyloidosis, as the specificity is high for patients with suspected cardiac involvement. Recent research from Dispenzieri et al. (14) suggests that elevated cardiac troponins may also be useful in the detection and prognosis of cardiac amyloidosis in patients with known systemic amyloidosis.
Recommendations for further study. It is noted that this study identified a subset of patients having evidence of both amyloidosis and myocarditis. This histopathologic finding was strikingly associated with a worse prognosis. To the best of our knowledge, this has not been previously reported. In this subset of patients, the ECG and echocardiographic findings were not significantly different from those with other forms of amyloidosis. This finding would favor the use of endomyocardial biopsy over noninvasive measures in the diagnosis of cardiac amyloid, as this histologic finding has important prognostic implications. We recommend further study to define this pathologic entity and its clinical features.
| APPENDIX |
|---|
|
|
|---|
![]() |
![]() |
For patients with a low voltage, the cut-off value of IVS thickness is equal to
1.98 cm, and the cut-off value of IVS thickness for a normal voltage is equal to
1.13 cm.
| Footnotes |
|---|
| References |
|---|
|
|
|---|
This article has been cited by other articles:
![]() |
H. Vogelsberg, H. Mahrholdt, C. C. Deluigi, A. Yilmaz, E. M. Kispert, S. Greulich, K. Klingel, R. Kandolf, and U. Sechtem Cardiovascular magnetic resonance in clinically suspected cardiac amyloidosis: noninvasive imaging compared to endomyocardial biopsy. J. Am. Coll. Cardiol., March 11, 2008; 51(10): 1022 - 1030. [Abstract] [Full Text] [PDF] |
||||
![]() |
L. T. Cooper, K. L. Baughman, A. M. Feldman, A. Frustaci, M. Jessup, U. Kuhl, G. N. Levine, J. Narula, R. C. Starling, J. Towbin, et al. The role of endomyocardial biopsy in the management of cardiovascular disease: A Scientific Statement from the American Heart Association, the American College of Cardiology, and the European Society of Cardiology Endorsed by the Heart Failure Society of America and the Heart Failure Association of the European Society of Cardiology Eur. Heart J., December 2, 2007; 28(24): 3076 - 3093. [Full Text] [PDF] |
||||
![]() |
J. B. Selvanayagam, P. N. Hawkins, B. Paul, S. G. Myerson, and S. Neubauer Evaluation and Management of the Cardiac Amyloidosis J. Am. Coll. Cardiol., November 27, 2007; 50(22): 2101 - 2110. [Abstract] [Full Text] [PDF] |
||||
![]() |
L. T. Cooper, K. L. Baughman, A. M. Feldman, A. Frustaci, M. Jessup, U. Kuhl, G. N. Levine, J. Narula, R. C. Starling, J. Towbin, et al. The Role of Endomyocardial Biopsy in the Management of Cardiovascular Disease: A Scientific Statement From the American Heart Association, the American College of Cardiology, and the European Society of Cardiology Endorsed by the Heart Failure Society of America and the Heart Failure Association of the European Society of Cardiology J. Am. Coll. Cardiol., November 6, 2007; 50(19): 1914 - 1931. [Full Text] [PDF] |
||||
![]() |
L. T. Cooper, K. L. Baughman, A. M. Feldman, A. Frustaci, M. Jessup, U. Kuhl, G. N. Levine, J. Narula, R. C. Starling, J. Towbin, et al. The Role of Endomyocardial Biopsy in the Management of Cardiovascular Disease: A Scientific Statement From the American Heart Association, the American College of Cardiology, and the European Society of Cardiology Circulation, November 6, 2007; 116(19): 2216 - 2233. [Full Text] [PDF] |
||||
![]() |
R. Y. Kwong and R. H. Falk Cardiovascular Magnetic Resonance in Cardiac Amyloidosis Circulation, January 18, 2005; 111(2): 122 - 124. [Full Text] [PDF] |
||||
![]() |
A. M. Maceira, J. Joshi, S. K. Prasad, J. C. Moon, E. Perugini, I. Harding, M. N. Sheppard, P. A. Poole-Wilson, P. N. Hawkins, and D. J. Pennell Cardiovascular Magnetic Resonance in Cardiac Amyloidosis Circulation, January 18, 2005; 111(2): 186 - 193. [Abstract] [Full Text] [PDF] |
||||
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | SUBSCRIPTIONS | CURRENT ISSUE | PAST ISSUES | CARDIOSOURCE | SEARCH | HELP | FEEDBACK |