Familial and primary (AL) cardiac amyloidosis: Echocardiographically similar diseases with distinctly different clinical outcomes

Objective-To determine whether patients with myocardial amyloidosis due either to AL (primary) amyloid or familial amyloid have distinguishing echocardiographic or electrocardiographic features; and to compare the prevalence of heart failure and survival in the two types of amyloidosis in relation to echocardiographic findings. Design-Blinded group comparison of randomly selected cases of cardiac amyloidosis. Setting-International referral centre for amyloid research and treatment. Patients-36 patients with cardiac amyloid heart disease, of whom 12 had familial and 24 had primary AL amyloidosis. Results-Familial and AL echocardiograms were morphologically indistinguishable, with similar left ventricular wall thickness, mean (SD) 15.4 (2.3) v 15.8 (2.5) mm, respectively; right ventricular wall thickness was also similar between amyloid types: 9.6 (2.8) v 9.7 (6.5) mm, respectively. Doppler indices of left and right ventricular function, left ventricular volume, and ejection fraction were also similar. Low voltage electrocardiograms (< 0.5 mV) were more common in the AL (16/24, 67%) than in the familial group (4/12, 25%), P < 0.05. The one year survival for familial and AL forms was 92% (11/12) v 38% (6/24), respectively, with virtually all deaths due to cardiac causes. Conclusions-Although cardiac involvement is echocardiographically indistinguishable, cardiac mortality is very different between the two forms of amyloidosis. Preservation of electrocardiographic voltage in familial amyloidosis suggests that the particular biochemical characteristics of distinct types of amyloid fibril have different pathological effects on the myocardium. This distinction becomes critical in the evaluation, treatment, and management of patients who have a diagnosis within the spectrum of the protein deposition diseases.