Cardiac Amyloidosis: Likelihood Ratios

Introduction: Amyloidosis represents abnormal deposition of amyloid fibrils within the soft tissues. It can affect various organs, including the heart where it deposits in the myocardium. Clinical features are those of diastolic Congestive Heart Failure.

Note that the diagnosis of systemic amyloidosis can be obtained by biopsy of other involved organs (though this does not necessarily prove cardiac involvement, which has a worse prognosis).

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The likelihood ratios of findings for Cardiac Amyloidosis are listed below. See the left navigation bar to change the display.

Pre-Test Probability (Prevalence): %.	Post-Test Probability (Predictive Value): %.	Switch to display mode.
Note that calculating probabilities from more than one** finding is inherently inaccurate because findings are not independent. (For example, using two positive findings that share a common pathogenesis is likely to overestimate the true probability.)

Good Positive and Negative Likelihood Ratios
Finding	Result	+LR	-LR
[ + ] Cardiac MRI	+ 0 -	8.8	0.1
another, smaller, study had sensitivity of 80% and specificity of 94%. Gold standard: endomyocardial biopsy. Findings on cardiac MRI are diffuse subendocardial delayed enhancement. Endomyocardial enhancement may be patchy, instead, but not in a vascular distribution. Another imaging feature is diffusely hypointense blood pool due to absorption of gadolinium by amyloid throughout the body. Study: JACC Cardiovasc Imaging. 2009 Dec;2(12):1369-77. PMID: 20083070 J Am Coll Cardiol. 2008 Mar 11;51(10):1022-30. PMID: 18325442
[ + ] Low ECG Voltage	+ 0 -	4.3	0.5
in patients referred for endomyocardial biopsy Study: J Am Coll Cardiol. 2004 Feb 4;43(3):410-5. PMID: 15013123 JACC Cardiovasc Imaging. 2009 Dec;2(12):1369-77. PMID: 20083070

Good Positive Likelihood Ratio
Finding	Result	+LR	-LR
[ + ] Speckled Myocardium	+ 0 -	6.5	0.8
on Trans-Thoracic Echocardiography. Also known as "granular myocardium." Study: J Am Coll Cardiol. 2004 Feb 4;43(3):410-5. PMID: 15013123

Poorly Diagnostic Findings
Finding	Result	+LR	-LR
[ + ] ECG	+ 0 -	1.7	0.6
Pseudo-infarct pattern (pathologic q waves without CAD) Study: J Am Coll Cardiol. 2004 Feb 4;43(3):410-5. PMID: 15013123
[ + ] Trans-Thoracic Echocardiography		Sensitivity = 47%
Diastolic dysfunction: specifically, "advanced (pseudonormal or restrictive) diastology." However, other diseases can cause diastolic dysfunction, especially hypertrophic cardiomyopathy such as from hypertension. Study: JACC Cardiovasc Imaging. 2009 Dec;2(12):1369-77. PMID: 20083070

Findings With Unspecified Accuracy
Finding	Result	+LR	-LR
[ + ] Endomyocardial Biopsy		No accuracy specified.
Gold-standard test, although clinically significant disease can be missed if patchy. Sources quote "virtually 100% sensitivity." Study: JACC Cardiovasc Imaging. 2009 Dec;2(12):1378-80. PMID: 20083071 Circulation. 2005 Sep 27;112(13):2047-60. PMID: 16186440