Atrial amyloidosis: mechanisms and clinical manifestations

Cardiac amyloidosis (CA) is now recognized as an important cause of heart failure. Increased wall thickness and diastolic dysfunction of the left ventricle are the most easily detectable manifestations of CA, but amyloid accumulates in all cardiac structures. Involvement of the left and right atria may be due to the haemodynamic effects of ventricular diastolic dysfunction, the effects of amyloid infiltration into the atrial wall, and the cardiotoxic damage of atrial cardiomyocytes by amyloid precursors. Atrial amyloidosis is an early manifestation of CA, and is associated with an increased risk of atrial fibrillation and thromboembolic events. Furthermore, atrial amyloidosis can be found even in the absence of systemic disease and ventricular involvement. This condition is named isolated atrial amyloidosis and is due to a local overproduction of atrial natriuretic peptide. In this review we summarize the evidence on the mechanisms and clinical relevance of atrial amyloidosis. [GRAPHICS] Atrial amyloidosis: pathophysiology and clinical manifestations. Atrial amyloidosis can manifest as part of a systemic disorder (as in amyloid light-chain [AL] or transthyretin [ATTR] amyloidosis), or be isolated (in the form due to atrial natriuretic type [ANP] accumulation); this last form is often associated with permanent or persistent atrial fibrillation. Atrial amyloidosis manifests with the reduction or loss of atrial systolic function (which can be assessed through speckle-tracking echocardiography and cardiovascular magnetic resonance), an increased risk of atrial fibrillation, and an increased thrombogenic risk; this last phenomenon may be related to blood stasis due to atrial dilation and dysfunction, atrial fibrillation, and also be promoted by amyloid infiltration in the atrial walls.