Background: Small deposits of amyloid are often found in the hearts of elderly patients. However, extensive deposition of transthyretin-derived amyloid fibrils in the heart (senile systemic amyloidosis [SSA]) can cause heart failure. The clinical features of SSA that involve the heart are ill defined, and the condition may be overlooked as a cause of heart failure. We sought to better define the clinical, echocardiographic, and electrocardiographic features of cardiac involvement in SSA and to compare them with the findings in patients with light chain-associated (AL) amyloidosis that affects the heart.
Methods: Eighteen consecutive patients with SSA and heart failure evaluated at a tertiary referral center for the diagnosis and treatment of amyloidosis were compared with 18 randomly selected patients with AL amyloidosis that involved the heart. All patients underwent a complete clinical and biochemical evaluation. Echocardiograms and electrocardiograms were interpreted by blinded investigators.
Results: Patients with SSA were older than those with AL amyloidosis and were all male. Proteinuria (protein output of >1 g per 24 hours) was common in AL amyloidosis but was not present in SSA. Left ventricular wall thickness was greater in patients with SSA than those with AL amyloidosis, but despite thicker walls and older age, the severity of heart failure was less in the SSA group and the median survival was much longer (75 vs 11 months; P = .003).
Conclusions: Senile systemic amyloidosis is a disorder of elderly men and is characterized by amyloidosis clinically limited to the heart. In contrast to the rapid progression of heart failure in AL amyloidosis, SSA results in slowly progressive heart failure. The difference in survival, despite evidence of more myocardial disease in the senile group, suggests that heart failure in AL amyloidosis may have a toxic component, possibly related to the circulating monoclonal light chain.