Clinical research: infiltrative cardiomyopathy
Noninvasive diagnosis of biopsy-proven cardiac amyloidosis

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Abstract

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.

Abbreviations

CHF
congestive heart failure
ECG
electrocardiogram/electrocardiographic
IVS
interventricular septal
LV
left ventricular
NYHA
New York Heart Association
OR
odds ratio

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This study was funded by the Charity Mae Foundation, Fargo, North Dakota.