Systemic amyloidosis

Systemic amyloidosis is a major cause of the renal injury; mostly due to direct kidney damage caused by deposits of an abnormal protein called amyloid; in the kidney parenchyma. In patients with cardiac amyloidosis; renal infarction is with acute kidney injury according to a new study in Mayo Clinic Proceedings, published by Elsevier. Investigators recommend that a diagnosis of renal infarction should systematically considered in patients with unexplained; acute kidney injury in the context of cardiac amyloidosis.

Patients with nephrotic syndrome

Cardiac involvement (the most relevant prognosis factor) is increasingly diagnosing in these patients; is frequently accompanied by significant dysfunction of other major organs. Amyloid cardiomyopathy may with thromboembolic events, mostly due to atrial fibrillation; leading to intracardiac thrombus formation, or promoted by the hypercoagulability state observed in patients with nephrotic syndrome.

Therefore in this observational study, investigators at the Amyloidosis Referral Center of Henri Mondor Hospital assessed the frequency of renal infarction in 87 patients with confirmed cardiac amyloidosis who underwent 99mTc-labeled DMSA renal scintigraphy. Three groups of patients were defined on the basis of the underlying amyloidosis disorder: AL amyloidosis in 24 patients; mutated-transthyretin amyloidosis in 24 patients; and wild-type transthyretin amyloidosis in 39 patients.

Context of cardiac amyloidosis

One of the study’s most significant findings is that acute kidney injury in a context of cardiac amyloidosis; may due to renal infarction. But the prevalence of renal infarction was relatively high (20.7 %) among the 87 patients with a definitive diagnosis of confirmed cardiac amyloidosis. So these cases evenly distributed between the three groups. Therefore at the time of renal scintigraphy, the frequency of acute kidney injury was higher in patients with renal infarction, and the likelihood of renal infarction diagnosis according to the presence or absence of acute kidney injury was 47.1 % and 14.5 %, respectively.

The investigators suggest that several factors, including direct kidney damage due to deposits of amyloid and indirect mechanisms of damage, such as renal failure due to low cardiac output, may nvolved in the renal failure observed in these patients. This study showed that after excluding heart transplant cases, patient survival did not differ significantly between patients with and without a diagnosis of renal infarction.

By contrast, the authors found that death- and heart transplant censored renal survival was significantly lower in patients with renal infarction. “Overall, these data suggest that renal infarction should probably add to the spectrum of renal manifestations related to systemic amyloidosis in cases of heart involvement. “Researcher recommends that a diagnosis of renal infarction should systematically considered in patients with unexplained acute kidney injury in the context of cardiac amyloidosis.”