Amyloidosis occurs due to the gradual deposition of protein aggregates, which may infiltrate more than one organ, progressively evolving to organ dysfunction. Prognosis is determined by the organ involved and by the involvement of the heart; cardiac amyloidosis (CA) leads to the worst evolution. CA may be due to myocardial deposition of the protein transthyretin, which is derived from liver tissue; this condition is known as ATTR. The other form of myocardial deposition is secondary to immunoglobulin light chain proteins, which are derived from a clone of plasma cells; this is known as the systemic form or AL amyloidosis. The ATTR and AL forms need to be differentiated, because they have different treatments.

CA is a common cause of restrictive cardiomyopathy, and it should always be considered in the context of patients with heart failure with preserved ejection fraction (HFpEF). Symptoms encompass reduced effort threshold, fatigue, and edema of the lower limbs. It is common for the conduction system to be involved, and reduced voltage of the QRS complex on electrocardiogram (ECG) is one of the diagnostic clues. Evolution with arrhythmias and atrioventricular block is also characteristic. ^–

[…]