Further information: Restrictive Cardiomyopathy (see p1285) and Autonomic Dysfunction and Hypotension (see p1883) from Cardiovascular Medicine, 3rd Edn*

From a pool of 233 patients who presented with systemic amyloidosis between 1990 and May 2008 to centers in Bologna and Pavia, Italy, the investigators of this study [1] compared the diagnostic/clinical profiles of the three types of systemic cardiac amyloidoses, namely acquired monoclonal immunoglobulin light-chain (AL); hereditary, mutated, transthyretin-related (ATTRm); and wild-type transthyretin-related (ATTRwt). There were 157 AL patients, 61 ATTRm patients, and 15 ATTRwt patients in this longitudinal study.

Myocardial involvement is common in all three forms, but while there are profound pathogenic differences in each form, most clinical studies to this point have addressed the disease as a single form. Generally considered a restrictive cardiomyopathy, the primary noninvasive marker of that form of cardiomyopathy (restrictive filling pattern) is not present in a majority of patients in each of the three groups. Although ventricular wall thickness, as well as systolic and diastolic function, commonly describe the severity of cardiac amyloidosis, these cardiac indicators are expressed differently in each of the three types. In addition, each group showed relevant hemodynamic differences and considerable allelic genetic heterogeneity. Average age at diagnosis was higher in AL than in ATTRm patients; all ATTRwt patients except one were elderly men. At diagnosis, mean left ventricular wall thickness was higher in ATTRwt than in ATTRm and AL. Left ventricular ejection fraction was moderately depressed in ATTRwt but not in AL or ATTRm. ATTRm patients displayed low QRS voltage less frequently (25% vs. 60% in AL; P<0.0001) or low voltage-to-mass ratio (1.1±0.5 vs.0.9±0.5; P=0.0001). AL patients appeared to have greater hemodynamic impairment. On multivariate analysis, ATTRm was a strongly favorable predictor of survival, and ATTRwt predicted freedom from major cardiac events.

The investigators concluded that AL, ATTRm, and ATTRwt should be evaluated as three different cardiac diseases from disease classification, diagnosis, and clinical management of the disease.

[1] Rapezzi C, Merlini G, Quarta CC, et al. Systemic Cardiac Amyloidoses. Circulation 2009;120:1203-1212

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